Linux 于 shell 变数 $#,$@,$0,$1,$2 含义解释:

$$        Shell自己PID（ProcessID）
$!         Shell背景上次执行Process的PID
$?         命令的结束代码（返回值）
$-         使用Set命令设定的Flag一览
$*         全部參数列表。如"$*"用「"」括起来的情况、以"$1 $2 … $n"的形式输出全部參数。
$@         全部參数列表。如"$@"用「"」括起来的情况、以"$1" "$2" … "$n" 的形式输出全部參数。

$#         加入到Shell的參数个数
$0         Shell本身的文件名称
$1～$n     加入到Shell的各參数值。$1是第1參数、$2是第2參数…。

#!/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" "$*"
printf "The complete list is %s\n" "$@"
printf "The complete list is %s\n" "$#"
printf "The complete list is %s\n" "$0"
printf "The complete list is %s\n" "$1"
printf "The complete list is %s\n" "$2"

[Aric@localhost ~]$ 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