bash $* 和 $@ 的区别
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The difference between $* and $@
提问by thb
Possible Duplicate:
What the difference between “$@” and “$*” in bash?
可能的重复：
bash 中的“$@”和“$*”有什么区别？
For years and on dozens of occasions, I have hesitated between the use of $*and $@in shell scripts. Having read the applicable section of Bash's manpage over and over again, having tried both $*and $@, I more or less completely fail to understand the practical difference of application between the two variables. Can you enlighten me, please?
多年来，在几十次的情况下，我在 shell 脚本中使用$*和之间犹豫不决$@。一遍又一遍地阅读 Bash 手册页的适用部分，尝试了$*和$@，我或多或少完全无法理解这两个变量之间的实际应用差异。你能帮我解惑吗？
I have been using $*recently, but don't ask me why. I don't know why, because I don't know why $@even exists, except as an almost exact synonym for $*.
我$*最近一直在用，但不要问我为什么。我不知道为什么，因为我什至不知道为什么$@会存在，除了作为$*.
Is there any practical difference?
有什么实际区别吗？
(I personally tend to use Bash, but remain agnostic regarding the choice of shell. My question is not specific to Bash as far as I know.)
（我个人倾向于使用 Bash，但对 shell 的选择保持不可知论。据我所知，我的问题不是针对 Bash 的。）
回答by FatalError
Unquoted, there is no difference -- they're expanded to all the arguments and they're split accordingly. The difference comes when quoting. "$@"expands to properly quoted arguments and "$*"makes all arguments into a single argument. Take this for example:
不加引号，没有区别——它们被扩展到所有参数，并相应地拆分。区别在于引用时。"$@"扩展为正确引用的参数"$*"并使所有参数成为单个参数。以这个为例：
#!/bin/bash
function print_args_at {
printf "%s\n" "$@"
}
function print_args_star {
printf "%s\n" "$*"
}
print_args_at "one" "two three" "four"
print_args_star "one" "two three" "four"
Then:
然后：
$ ./printf.sh
one
two three
four
one two three four
回答by William Pursell
Consider:
考虑：
foo() { mv "$@"; }
bar() { mv "$*"; }
foo a b
bar a b
The call to foo will attempt to mv file a to b. The call to bar will fail since it calls mv with only one argument.
对 foo 的调用将尝试将文件 a 转为 b。对 bar 的调用将失败，因为它只用一个参数调用 mv。
回答by glenn Hymanman
Note also that "$@"is magic onlywhen there's nothing else in the quotes. These are identical:
另请注意，只有当引号中没有其他内容时，这才"$@"是魔术。这些是相同的：
set -- a "b c" d
some_func "foo $*"
some_func "foo $@"
In both cases, some_func receives one argument.
在这两种情况下， some_func 都接收一个参数。
