Explanation of the meaning of shell variable $#,$@,$0,$1,$2 in "Shell" Linux && set keyword usage

Excerpt from: Abs_guide

: http://www.tldp.org/LDP/abs/abs-guide.pdf

The meaning of shell variable $#,[email protected],$0,$1,$2 in Linux is explained: Variable Description: $$ The PID of the shell itself (ProcessID) $! PID of the Shell's last running background process $? End code of the last Run command (return value) $- Flag at a glance using the SET command $* All parameter lists. such as "$*" in the Case of "" ", in the form of" $ $ ... $n "output all parameters. [Email protected] All parameter lists. such as "[email protected]" with "" "in the case, with" $ "" $ "... All parameters are output in the form "$n". $# Number of arguments added to the shell $ The name of the shell itself $1~ $n Each parameter value added to the shell. $ $ is the 1th parameter, and the $ = is the 2nd parameter ....

Example:

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1 #!/bin/bash 2 # 3 printf "The complete list is %s\n" "$$" 4 printf "The complete list is %s\n" "$!" 5 printf "The complete list is %s\n" "$?" 6 printf "The complete list is %s\n" "$*" 7 printf "The complete list is %s\n" "[email protected]" 8 printf "The complete list is %s\n" "$#" 9 printf "The complete list is %s\n" "$0"10 printf "The complete list is %s\n" "$1"11 printf "The complete list is %s\n" "$2

Results:

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[[email protected] ~]$ bash params.sh 123456 QQThe complete list is 24249The complete list isThe complete list is 0The complete list is 123456 QQThe complete list is 123456The complete list is QQThe complete list is 2The complete list is params.shThe complete list is 123456The complete list is QQ

Shell variables in the

Shell Linux $#,[email protected] , $0,$1 , the meaning of the $ $ explanation && Set keyword using the