Linux中shell变量$0,$?等含义

linux中shell变量$#,[email protected],$0,$1,$2的基本含义: 
变量说明: 
$$ 
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 
添加到Shell的各参数值。$1是第1参数、$2是第2参数…。

实例：

$ vim dollar.sh

#!/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" "$0"
printf "The complete list is %s\n" "$1"
printf "The complete list is %s\n" "$2"
printf "The complete list is %s\n" "$3"

结果展示：

[[email protected] ]$ sh dollar.sh 123456 654321 qq ww
The complete list is 3278
The complete list is
The complete list is 0
The complete list is 123456 654321 qq ww
The complete list is 123456
The complete list is 654321
The complete list is qq
The complete list is ww
The complete list is 4
The complete list is dollar.sh
The complete list is 123456
The complete list is 654321
The complete list is qq