linux编程

$* 和 [email protected] 的区别

$* 和 [email protected] 都表示传递给函数或脚本的所有参数，不被双引号(" ")包含时，都以"$1" "$2" … "$n" 的形式输出所有参数。

但是当它们被双引号(" ")包含时，"$*" 会将所有的参数作为一个整体，以"$1 $2 … $n"的形式输出所有参数；"[email protected]" 会将各个参数分开，以"$1" "$2" … "$n" 的形式输出所有参数。

下面的例子可以清楚的看到 $* 和 [email protected] 的区别：

 1 #!/bin/bash
 2 echo "\$*=" $*
 3 echo "\"\$*\"=" "$*"
 4
 5 echo "\[email protected]=" [email protected]
 6 echo "\"\[email protected]\"=" "[email protected]"
 7
 8 echo "print each param from \$*"
 9 for var in $*
10 do
11     echo "$var"
12 done
13
14 echo "print each param from \[email protected]"
15 for var in [email protected]
16 do
17     echo "$var"
18 done
19
20 echo "print each param from \"\$*\""
21 for var in "$*"
22 do
23     echo "$var"
24 done
25
26 echo "print each param from \"\[email protected]\""
27 for var in "[email protected]"
28 do
29     echo "$var"
30 done

执行 ./test.sh "a" "b" "c" "d"，看到下面的结果：

$*=  a b c d
"$*"= a b c d
[email protected]=  a b c d
"[email protected]"= a b c d
print each param from $*
a
b
c
d
print each param from [email protected]
a
b
c
d
print each param from "$*"
a b c d
print each param from "[email protected]"
a
b
c
d