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--- shell_progammierung [2010/09/06 12:22] – created michael
+++ shell_progammierung [2021/04/24 07:40] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Shell Programmierung (bash) ======
+==== Abarbeitung der Kommandozeile ====
+| Read until the first command separator | & && \| \| ; < > |
+| Split the command | cat /etc/passwd \| wc -l |
+| substitute variables | $MYVAR wird durch Wert ersetzt |
+| substitute commands | Backticks oder () |
+| stdin, stdout and stderr| re(>/dev/null, 2>&1,...)|
+| Zuweisungen an Variablen durchführen| |
+| Sonderzeichen ersetzen| Sonderzeichen wie *, ?, [] werden ersetzt. Ausser Sie stehen in "" |
+| Fertiges Kommando ausführen |  |
+==== AWK ====
+|FS|Separator|
+|RS|Record Sepatator. Normally Linbreak (\n)|
+|NF|Number of Fields in a Record|
+|NR|Number of active Record|
+|ARGV|Array of all awk parameters|
+|ARGC|number of all awk parameters|
+|OFS|Output field separator|
+|ORS|Output record separator|
+   awk '{print $0}'
+   df -hk | egrep "\/$" | awk '{print $5}'
+   df -hk | awk '/sda/{print $5}'
+   df -hk | awk 'NR>1{print $1,$3,$7}'
+==== Commandos ====
+|exec||
+|break||
+|continue||
+|declare||
+|eval||
+|getops||
+|let||
+|login||
+|umask||
+|readonly||
+|trap||
+|type||
+|typset||
+|exit||
+==== Funktionen ====
+  summe()
+  {
+    MYVAR1=$1
+    MYVAR2=$2
+    "let ERG=$MYVAR1+$MYVAR2"
+    ECHO $ERG
+  }
+  ERG=`summe 5 6`
+  echo $ERG
+==== Variablen ====
+  HISTSIZE
+  TMOUT
+  ENV
+  OSTYPE
+  HOSTTYPE
 ==== Umleiten ====
@@ Line 7: / Line 73: @@
   STDERR 2>
-Bsp: STDERR auf STDOUT
+Example: bypass STDERR to STDOUT
 >&1
+Example: bypass STDOUT and STDERR
+  >/dev/null 2>&1
 ==== IF ====
@@ Line 20: / Line 89: @@
   fi
 Weitere Parameter: -lt, -gt, !=, <, >
+==== Meta-Zeichen ====
+  ?(string) 0-1mal string
+  *(string) x-mal string
+  +(string) 1-xmal string
+  @(string) 1mal string
+  !(string) nicht string
 ==== TEST-Command ====
@@ Line 35: / Line 112: @@
 ==== WHILE ====
+   while [ expression ]
+   do
+       dosomething
+   done
+==== WHILE lines in file ====
+   while read i; do
+      echo $i
+   done < list.txt