diff --git a/20210423/echo-1.txt b/20210423/echo-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..e39b07beb181a870f7683da662d54ac3fd45bdc3
--- /dev/null
+++ b/20210423/echo-1.txt
@@ -0,0 +1,4 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..e20f9bccbce32e74e0dbb3f5caa87cf0874d5c6b
--- /dev/null
+++ b/20210423/echo-2.txt
@@ -0,0 +1,3 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..6bfef64301ada2552a032410405fc95828e9e8d2
--- /dev/null
+++ b/20210423/exec-output-1.txt
@@ -0,0 +1,12 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..8da1d6318741453f610d9c55640af13948673dff
--- /dev/null
+++ b/20210423/exec-output-2.txt
@@ -0,0 +1,11 @@
+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 $(locate listings.pdf | head -1)
+cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/exec-output-3.txt b/20210423/exec-output-3.txt
new file mode 100644
index 0000000000000000000000000000000000000000..3e8cf4e13e86960215f0b93c0cea0faa0390741c
--- /dev/null
+++ b/20210423/exec-output-3.txt
@@ -0,0 +1,4 @@
+cassini/home/peter/bo/2021ss/bs/20210423> file_template=$(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
new file mode 100644
index 0000000000000000000000000000000000000000..51a80ae973e07b4283cb2ca38861b2dad13b930c
--- /dev/null
+++ b/20210423/find-1.txt
@@ -0,0 +1,15 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..2d9eaa12bc77f960e7f81e0777b947349d052148
--- /dev/null
+++ b/20210423/find-2.txt
@@ -0,0 +1,6 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..0e1f55793dd6e353ecb653529b1d5918f87124a0
--- /dev/null
+++ b/20210423/find-3.txt
@@ -0,0 +1,17 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..07def8f1d358691756227aa407c8708828b623f4
--- /dev/null
+++ b/20210423/find-4.txt
@@ -0,0 +1,38 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..8baf885795b845da6f19f3cacd5aae66c5f14172
--- /dev/null
+++ b/20210423/find-5.txt
@@ -0,0 +1,22 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..f6e41af6c90d4bf75e250fc75dd4d0a69079de1a
--- /dev/null
+++ b/20210423/for-1.txt
@@ -0,0 +1,21 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..fae0292bc4037a527da95d445713b5d6aa4cac3d
--- /dev/null
+++ b/20210423/for-2.txt
@@ -0,0 +1,18 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..c4c92d1f6c8daebb56b21875765792fd91adf251
--- /dev/null
+++ b/20210423/grep-1.txt
@@ -0,0 +1,22 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..2a80ca2380598ac462abf0d8da3b4271d51b50b8
--- /dev/null
+++ b/20210423/grep-2.txt
@@ -0,0 +1,26 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..f88ade45ccb68507fb5df7a99948d6908149670b
--- /dev/null
+++ b/20210423/grep-3.txt
@@ -0,0 +1,36 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..daf3938a688b451f09472da0c47bd349ca191d21
--- /dev/null
+++ b/20210423/grep-4.txt
@@ -0,0 +1,95 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..8b3c701f797a93de86e7e389148d1dfffe545a5b
--- /dev/null
+++ b/20210423/grep-5.txt
@@ -0,0 +1,26 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..7a3e3a6323b5d989be3bbbe96f45e6d4fc8e47fe
--- /dev/null
+++ b/20210423/hello-error.txt
@@ -0,0 +1 @@
+grep: test: Ist ein Verzeichnis
diff --git a/20210423/hello-files-and-error.txt b/20210423/hello-files-and-error.txt
new file mode 100644
index 0000000000000000000000000000000000000000..b0b29831cd4b26cd684768828693d85ba98be314
--- /dev/null
+++ b/20210423/hello-files-and-error.txt
@@ -0,0 +1,9 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..3dd40b28f78abd44ab7b51bdaebb797cb9600b5d
--- /dev/null
+++ b/20210423/hello-files.txt
@@ -0,0 +1,6 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..3e8cf4e13e86960215f0b93c0cea0faa0390741c
--- /dev/null
+++ b/20210423/if-1.txt
@@ -0,0 +1,4 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..635b5dfa33342183953e2083727af58ce5423eb4
--- /dev/null
+++ b/20210423/if-2.txt
@@ -0,0 +1,17 @@
+#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
new file mode 100644
index 0000000000000000000000000000000000000000..ee2a3d913c0b3dea7e62ab80d8ea91ff9f22ef91
--- /dev/null
+++ b/20210423/if-3.txt
@@ -0,0 +1,16 @@
+#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
new file mode 100644
index 0000000000000000000000000000000000000000..a458917ec947aa22e0a63ec11117506e7872cd04
--- /dev/null
+++ b/20210423/if-4.txt
@@ -0,0 +1,9 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..87d825ae4e2adf20e628e84b07e7142fac249ae8
--- /dev/null
+++ b/20210423/input-1.txt
@@ -0,0 +1,13 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..5efddfaa5b27bc90bc5abc5c47a4d2dc0739366c
--- /dev/null
+++ b/20210423/input-2.txt
@@ -0,0 +1,5 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..817f3fdaa6508d437ad2a90bace2475009d1c08b
--- /dev/null
+++ b/20210423/iostreams-1.txt
@@ -0,0 +1,4 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..7257290e423d184a5a70fa4eea36b070c49e986a
--- /dev/null
+++ b/20210423/iostreams-2.txt
@@ -0,0 +1,5 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..9d143b406ba97ec0878c30ff2fc40a0619ea7383
--- /dev/null
+++ b/20210423/iostreams-3.txt
@@ -0,0 +1,18 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..e4c57d3fdc6d5a09317b409627de2380bbc6c360
--- /dev/null
+++ b/20210423/iostreams-4.txt
@@ -0,0 +1,20 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..e8b40291644f11d7407fdc3ca0114a778f36c070
--- /dev/null
+++ b/20210423/iostreams-5.txt
@@ -0,0 +1,12 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..08385ba4fcc8591c2133355f67cbd70e5a2ae94d
--- /dev/null
+++ b/20210423/iostreams-6.txt
@@ -0,0 +1,3 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..ca5f11b88d5f942f3099343d5cd275c3f8543720
--- /dev/null
+++ b/20210423/iostreams-7.txt
@@ -0,0 +1,4 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..e21ca489f3d9c6a2fa8b1fad86b27bd046ddbcdb
--- /dev/null
+++ b/20210423/iostreams-8.txt
@@ -0,0 +1,3 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..332ab2c296dd28a2aac6985bddeb6dfc56242bbf
--- /dev/null
+++ b/20210423/iostreams-9.txt
@@ -0,0 +1,10 @@
+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
new file mode 100755
index 0000000000000000000000000000000000000000..89423aeae1bb6246e6d0c5acd58991227648b97b
--- /dev/null
+++ b/20210423/params-1.sh
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo $1
diff --git a/20210423/params-1.txt b/20210423/params-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..99bfcff2538974d2105920485a213c4c663a2a3c
--- /dev/null
+++ b/20210423/params-1.txt
@@ -0,0 +1,17 @@
+#!/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
new file mode 100755
index 0000000000000000000000000000000000000000..7102914424002091e56660128cb4bfe1410e9117
--- /dev/null
+++ b/20210423/params-2.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+shift
+echo $1
diff --git a/20210423/params-2.txt b/20210423/params-2.txt
new file mode 100644
index 0000000000000000000000000000000000000000..c6d85aaf63a686ea9737a9d54ee8e63cfc7f3095
--- /dev/null
+++ b/20210423/params-2.txt
@@ -0,0 +1,9 @@
+#!/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
new file mode 100755
index 0000000000000000000000000000000000000000..a21f4a7afd3fa8d2c4b63e57f46cdd3433697322
--- /dev/null
+++ b/20210423/params-3.sh
@@ -0,0 +1,4 @@
+#!/bin/bash
+
+shift 2
+echo $1
diff --git a/20210423/permissions-1.txt b/20210423/permissions-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..7753ba766a0746572d1bbc91782f6e6868c8120a
--- /dev/null
+++ b/20210423/permissions-1.txt
@@ -0,0 +1,8 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..52e61e32cdf3dbe16dcc2dc289d61bcb519472e6
--- /dev/null
+++ b/20210423/pipes-1.txt
@@ -0,0 +1,5 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..1297679515178283114f974cc27601bd871b2646
--- /dev/null
+++ b/20210423/pipes-2.txt
@@ -0,0 +1,6 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..0b875199efc3fd84a2990dd328c837653ee304f7
--- /dev/null
+++ b/20210423/pipes-3.txt
@@ -0,0 +1,12 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..575936dd9c4052de1f7c356eacb0bd400465b8c7
--- /dev/null
+++ b/20210423/pipes-4.txt
@@ -0,0 +1,6 @@
+ 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 $(find ~/bo/ -type f -name "*klausur*.pdf" | grep -v "\-fig[0-9]")
diff --git a/20210423/pipes-5.txt b/20210423/pipes-5.txt
new file mode 100644
index 0000000000000000000000000000000000000000..72529eecee6184f661445369ca67be8674070d40
--- /dev/null
+++ b/20210423/pipes-5.txt
@@ -0,0 +1,14 @@
+cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null unix-20210423.tex test-1.c test-4.c params-2.sh
+ test-2.c test-3.c params-1.sh params-3.sh
+cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | cat
+unix-20210423.tex
+test-2.c
+test-1.c
+test-3.c
+test-4.c
+params-1.sh
+params-2.sh
+params-3.sh
+cassini/home/peter/bo/2021ss/bs/20210423> ls -rt *.c *.cpp *.sh *.py *.tex *.diff 2>/dev/null | tail -1
+params-3.sh
+cassini/home/peter/bo/2021ss/bs/20210423>
diff --git a/20210423/sed-1.txt b/20210423/sed-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..412c17d0eacee74c1e535766c846509c00f8f385
--- /dev/null
+++ b/20210423/sed-1.txt
@@ -0,0 +1,7 @@
+cassini/home/peter/bo/2021ss/bs/20210423> file_template=$(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
new file mode 100644
index 0000000000000000000000000000000000000000..b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac
--- /dev/null
+++ b/20210423/test-1.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main (void)
+{
+ printf ("Hello, world!\n");
+ return 0;
+}
diff --git a/20210423/test-2.c b/20210423/test-2.c
new file mode 100644
index 0000000000000000000000000000000000000000..b19d80e9bd0bd7c5ed8f54b20c6a50d9166f03ac
--- /dev/null
+++ b/20210423/test-2.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main (void)
+{
+ printf ("Hello, world!\n");
+ return 0;
+}
diff --git a/20210423/test-3.c b/20210423/test-3.c
new file mode 100644
index 0000000000000000000000000000000000000000..b12567c05cf7cf3d7b90f0f22635e78c3bcb6819
--- /dev/null
+++ b/20210423/test-3.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main (void)
+{
+ printf ("Hallo, world!\n");
+ return 0;
+}
diff --git a/20210423/test-4.c b/20210423/test-4.c
new file mode 100644
index 0000000000000000000000000000000000000000..c79c1c33e2c85d817fe9abfe7f6f52f4cde29996
--- /dev/null
+++ b/20210423/test-4.c
@@ -0,0 +1,7 @@
+#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
new file mode 100644
index 0000000000000000000000000000000000000000..5f428754dd482e6044245d267994223e04856f6f
--- /dev/null
+++ b/20210423/test-5.c
@@ -0,0 +1,7 @@
+#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
new file mode 100644
index 0000000000000000000000000000000000000000..08ad6a1254fc4d660e24087fa401156bde9245da
--- /dev/null
+++ b/20210423/test-6.c
@@ -0,0 +1,7 @@
+#include <stdio.h>
+
+int main (void)
+{
+ printf ("Bonjour le monde !\n")
+ return 1
+}
diff --git a/20210423/test.bc b/20210423/test.bc
new file mode 100644
index 0000000000000000000000000000000000000000..a922b775b5315bf2bc04d96cbdaba8d32c911404
--- /dev/null
+++ b/20210423/test.bc
@@ -0,0 +1 @@
+2 + 2
diff --git a/20210423/test.txt b/20210423/test.txt
new file mode 100644
index 0000000000000000000000000000000000000000..25cd896083bf6c919d1d2b70b8b06122e72cf5ca
--- /dev/null
+++ b/20210423/test.txt
@@ -0,0 +1,2 @@
+Dies ist ein Test.
+Dies auch.
diff --git a/20210423/unix-20210423.pdf b/20210423/unix-20210423.pdf
new file mode 120000
index 0000000000000000000000000000000000000000..5088e123b7cf3a13f3e818d8be9c5b5c70f0b056
--- /dev/null
+++ b/20210423/unix-20210423.pdf
@@ -0,0 +1 @@
+../20210409/unix-20210409.pdf
\ No newline at end of file
diff --git a/20210423/unix-20210423.tex b/20210423/unix-20210423.tex
new file mode 120000
index 0000000000000000000000000000000000000000..8548cff5b6f4928e1bacf91d66f0f6d1ed4966da
--- /dev/null
+++ b/20210423/unix-20210423.tex
@@ -0,0 +1 @@
+../20210409/unix-20210409.tex
\ No newline at end of file
diff --git a/20210423/vic b/20210423/vic
new file mode 100755
index 0000000000000000000000000000000000000000..063daa1366b11b0914121af554892a2e2c68183f
--- /dev/null
+++ b/20210423/vic
@@ -0,0 +1,39 @@
+#!/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 "$new_file_name"
diff --git a/20210423/vicat b/20210423/vicat
new file mode 100755
index 0000000000000000000000000000000000000000..c3565c648e9320f871f275b135cef86d4c918ebd
--- /dev/null
+++ b/20210423/vicat
@@ -0,0 +1,5 @@
+#!/bin/bash
+/usr/bin/vim -X -c 'set sw=2' -c 'set expandtab' -c 'set ai' -c 'set nowrap' "$@"
+clear
+shift $(( $# - 1 ))
+cat "$1"
diff --git a/20210423/while-1.txt b/20210423/while-1.txt
new file mode 100644
index 0000000000000000000000000000000000000000..a4492468164b8eac520137d6b0ee2fee75d73b29
--- /dev/null
+++ b/20210423/while-1.txt
@@ -0,0 +1,9 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..3920a02af05ba9acec1de7c974d48d2f58a78fc9
--- /dev/null
+++ b/20210423/while-2.txt
@@ -0,0 +1,11 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..d90662084ec2f492a2ad34962b95b337e4892961
--- /dev/null
+++ b/20210423/while-3.txt
@@ -0,0 +1,5 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..be63f871cba519dea269f74017800e6f6ebe0284
--- /dev/null
+++ b/20210423/wildcards-1.txt
@@ -0,0 +1,19 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..d42e553e09454a564d0b8da903de9229d75d7c1f
--- /dev/null
+++ b/20210423/wildcards-2.txt
@@ -0,0 +1,22 @@
+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
new file mode 100644
index 0000000000000000000000000000000000000000..2ab73de48e5fec561ce24442f5b66935a3a2855a
--- /dev/null
+++ b/20210423/wildcards-3.txt
@@ -0,0 +1,9 @@
+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
new file mode 100755
index 0000000000000000000000000000000000000000..9964c95684e445d54fa4d26b6eb096257bed767c
--- /dev/null
+++ b/20210423/xkcd
@@ -0,0 +1,42 @@
+#!/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