访问shell脚本参数

  所谓的位置参数指的也就是shell脚本的命令行参数。在shell函数里面，它们也可以同时是函数的参数。各参数都由整数命名，但超过了9就应该用大括号把数字框起来。

[badboy@localhost ~]$ set -- 1 2 3 4 5 6 7 8 9 10
[badboy@localhost ~]$ echo the first number is $1
the first number is 1
[badboy@localhost ~]$ echo the tenth number is ${10}
the tenth number is 10
 
 下面我主要介绍的是特殊“变量”提供对传递的参数的总数的访问，以及一次对所有参数的访问。

 1. $#
   提供传递到shell脚本或函数的参数总数。当你为了处理选项和参数而建立循环时会很有用哈。。
[badboy@localhost ~]$ echo the number of arg is $#
the number of arg is 10

 2. $*,$@
   一次表示所有的命令行参数。
[badboy@localhost ~]$ echo all number is $*
all number is 1 2 3 4 5 6 7 8 9 10
[badboy@localhost ~]$ echo all number is $@
all number is 1 2 3 4 5 6 7 8 9 10

 3."$*"
    将所有的命令行参数视为单个字符串。等同于"$1 $2 $3..."。
           
[badboy@localhost ~]$ for i in "$*"
> do echo i is $i
> done
i is 1 2 3 4 5 6 7 8 9 10

 4. "$@"
     将所有命令行参数视为单个字符串，等同于"$1","$2","$3"....。。
[badboy@localhost ~]$ for i in "$@"
> do echo i is $i
> done
i is 1
i is 2
i is 3
i is 4
i is 5
i is 6
i is 7
i is 8
i is 9
i is 10