Explanation of the meaning of shell variable $#,$@,$0,$1,$2 in Linux

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:

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:

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

Linux shell variable $#,[email protected], $0,$1,$2 meaning explanation