Variable Description:
$$ Shell本身的PID(ProcessID) $! Shell最后运行的后台Process的PID $? 最后运行的命令的结束代码(返回值) $- 使用Set命令设定的Flag一览 $* 所有参数列表。如"$*"用「"」括起来的情况、以"$1 $2 … $n"的形式输出所有参数。 [email protected] 所有参数列表。如"[email protected]"用「"」括起来的情况、以"$1" "$2" … "$n" 的形式输出所有参数。 $# 添加到Shell的参数个数 $0 Shell本身的文件名 $1~$n
Example:
#!/bin/bash#printf "The complete list is%s\n" "$$"printf "The complete list is%s\n" "$!"printf "The complete list is%s\n" "$?"printf "The complete list is%s\n" "$*"printf "The complete list is%s\n" "[email protected]"printf "The complete list is%s\n" "$#"printf "The complete list is%s\n" "$"printf "The complete list is%s\n" "$"printf "The complete list is%s\n" "$"
Results:
[[email protected] ~]$ 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
For more explanations, see the following document
: http://www.tldp.org/LDP/abs/abs-guide.pdf
Shell variables in Linux $#,[email protected] , $0,$1,$2 Explanation of Meaning: