linux中shell变量$#,$@,$0,$1,$2的含义解释: 
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。 
$@ 
所有参数列表。如"$@"用「"」括起来的情况、以"$1" "$2" … "$n" 的形式输出所有参数。 
$# 
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…。 

示例：
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" "$*"
 7 printf "The complete list is %s\n" "$@"
 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

结果：
[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