Linux Bash Shell $*和$@的区别

在 Linux Bash Shell 中，$* 和 $@ 都表示参数列表中的所有参数，它们在具体使用中会有哪些不同呢？这里我们可以写一个 Shell 脚本做实验：

#!/bin/bash

# This script is to verify the difference between $* and $@

echo Dollar Star is $*
echo "Dollar Star in double quotes is $*"

echo Dollar At is $@
echo "Dollar At in double quotes is $@"

echo
echo "Looping through Dollar Star"
for i in $*
do
echo "parameter is $i"
done
echo
echo "Looping through Dollar Star with double quotes"
for i in "$*"
do
echo "Parameter is $i"
done

echo
echo "Looping through Dollar At"
for i in $@
do
echo "Parameter is $i"
done
echo
echo "Looping through Dollar At with double quotes"
for i in "$@"
do
echo "Parameter is $i"
done

文件保存为 star.sh，并给予可执行权限：

# chmod 755 star.sh

然后我们执行以下命令：

# ./star.sh 1 "2  3 " 4   5

结果如下：

Dollar Star is 1 2 3 4 5
Dollar Star in double quotes is 1 2  3  4 5
Dollar At is 1 2 3 4 5
Dollar At in double quotes is 1 2  3  4 5

Looping through Dollar Star
parameter is 1
parameter is 2
parameter is 3
parameter is 4
parameter is 5

Looping through Dollar Star with double quotes
Parameter is 1 2  3  4 5

Looping through Dollar At
Parameter is 1
Parameter is 2
Parameter is 3
Parameter is 4
Parameter is 5

Looping through Dollar At with double quotes
Parameter is 1
Parameter is 2  3
Parameter is 4
Parameter is 5

由以上输出结果可以得出两者的相同点如下：

1、直接输出不保留空格

2、带双引号输出会保留带引号的空格

3、不带双引号循环遍历的输出结果一样：每个字符串单独输出

不同点如下：

1、带双引号遍历$*相当于带双引号输出$*

2、带双引号遍历$@分别输出每个参数，带双引号的参数保留空格输出