Linux学习之shell编程二

shell script 的默认变量

$0,$1......

在shell脚本里面，执行的脚本文件名就是$0变量，$1就是脚本的第一个参数。还有一些特殊的变量，比如：

$#：代表后接的参数个数

$@：代表$1,$2,$3,$4之意

$*：代表“$1c$2c$3c$4”，其中c为分隔符，默认为空格

shift：可以偏移变量号码，比如shift ,或者shift 2可以将变量代码向左移动1次或2次

#!/bin/bash
#filename:shell05.sh
echo "The number of variables is ==> $#"
echo "The total variable is ==> '$@'"
echo "The first variable is ==> $1"
shift #偏移一次
echo "The number of variables is ==> $#"
echo "The total variable is ==> '$@'"
echo "The first variable is ==> $1"

运行./shell05.sh one two three four

得到结果：

The number of variables is ==> 4
The total variable is ==> 'one two three four'
The first variable is ==> one
The number of variables is ==> 3
The total variable is ==> 'two three four'
The first variable is ==> two