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Shell Programmierung (bash)

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

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}'

summe()
{
  MYVAR1=$1
  MYVAR2=$2
  "let ERG=$MYVAR1+$MYVAR2"
  ECHO $ERG
}
ERG=`summe 5 6` 
echo $ERG

HISTSIZE 
TMOUT
ENV
OSTYPE
HOSTTYPE

STDIN < 
STDOUT > >> 
STDERR 2>

Example: bypass STDERR to STDOUT

2>&1

Example: bypass STDOUT and STDERR

>/dev/null 2>&1

Comparison:

if [ $VAR == "string" ]
   machwas
fi
if [ $VAR -eq 5 ]
   machwas
fi

Weitere Parameter: -lt, -gt, !=, <, >

?(string) 0-1mal string
*(string) x-mal string
+(string) 1-xmal string
@(string) 1mal string
!(string) nicht string

Check Files or Directories

test -d directory
test -e file
test -f file
test ! ( ausdruck)

 while [ expression ]
 do
     dosomething
 done

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