$0
The filename of the current script.
2$n
These variables correspond to the arguments with which a script was invoked. Here n is a positive decimal number corresponding to the position of an argument (the first argument is $1, the second argument is $2, and so on).
3$#
The number of arguments supplied to a script.
4$*
All the arguments are double quoted. If a script receives two arguments, $* is equivalent to $1 $2. 获取所有的命令行参数
5$@
All the arguments are individually double quoted. If a script receives two arguments, $@ is equivalent to $1 $2.获取所有的命令行参数
6$?
The exit status of the last command executed.
7$$
The process number of the current shell. For shell scripts, this is the process ID under which they are executing.
8$!
The process number of the last background command.
举个小例子：
#!/bin/sh for TOKEN in $* do echo $TOKEN done现实结果如下面：
$./test.sh Zara Ali 10 Years Old Zara Ali 10 Years Old
