在 bash 中执行 for-each
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Executing for-each in bash
提问by perimosocordiae
I'm looking to write a Bash one-liner that calls a function once for each item in a list. For example, given the list
我正在寻找编写一个 Bash one-liner，为列表中的每个项目调用一次函数。例如，给定列表
foo bar baz和程序“cowsay”，它将产生：
_____
< foo >
-----
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
_____
< bar >
-----
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
_____
< baz >
-----
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
(Maybe with additional text in between, doesn't really matter)
（也许中间有额外的文字，并不重要）
I know I can do this with a bash script:
我知道我可以用 bash 脚本做到这一点：
#!/bin/sh
for w in $@; do
cowsay $w
done
But I can't imagine that there isn't another way to do it.
但我无法想象没有其他方法可以做到这一点。
EDIT: I wasn't very clear in my initial question, I think. I want to be able to do something like this without writing a bash script:
编辑：我认为我最初的问题不是很清楚。我希望能够在不编写 bash 脚本的情况下做这样的事情：
locate foo | sed s/bar/baz/ | [other-processing] | [insert-magic-here] cowsay
The point is that I'm trying to avoid having to write a script, so that I can just add it to my pipe chain and not think about it.
关键是我试图避免编写脚本，这样我就可以将它添加到我的管道链中而不去考虑它。
回答by Nicholas Riley
Sounds like you want to use xargs then.
听起来你想使用 xargs 。
$ echo foo bar | xargs -n 1 cowsay
_____
< foo >
-----
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
_____
< bar >
-----
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
回答by quack quixote
You want xargs. Without a for, while, or untilloop structure, xargsis about the only thing that will do what you ask.
你要xargs。没有for, while, 或until循环结构，xargs是唯一可以满足您要求的事情。
Use -n1if you need xargs to execute your command for each input, instead of executing with many inputs as separate arguments. Your example becomes:
使用-n1，如果你需要xargs的为每个输入执行你的命令，而不是用很多投入作为单独的参数执行。你的例子变成：
$ locate foo | sed s/bar/baz/ | [other-processing] | xargs -n1 cowsay
回答by Kimmo Puputti
In one line:
在一行中：
for i in foo bar baz; do cowsay $i; done
Or more clearly:
或者更清楚：
foobar="foo bar baz"
for i in $foobar
do
cowsay $i
done
回答by camh
As other's have said, xargs(1) is what you want, but it is not always suitable. Most often when it has failed for me, it was when I wanted to run a shell function. xargs runs an executable command.
正如其他人所说， xargs(1) 是您想要的，但并不总是合适的。大多数情况下，当它对我来说失败时，是当我想运行一个 shell 函数时。xargs 运行一个可执行命令。
You can put a loop in your pipeline without needing to put it in a shell script:
您可以在管道中放置一个循环，而无需将其放入 shell 脚本中：
$ locate foo | sed s/bar/baz/ | [other-processing] | while read line ; do cowsay "$line" ; done
If cowsay was a shell function, this pipeline would work, but not with xargs.
如果 cowsay 是一个 shell 函数，这个管道可以工作，但不能与 xargs 一起使用。
回答by R Samuel Klatchko
You could write a function that turns this into a liner:
您可以编写一个将其转换为班轮的函数：
function foreach
{
func=; shift
for arg in $@; do
${func} ${arg}
done
}
And then invoke it like:
然后像这样调用它：
foreach cosway foo bar baz
回答by jkndrkn
If you are not interested in using a "for" loop, then your other options to iterate over a list of strings is to use a "while" or "until" loop.
如果您对使用“for”循环不感兴趣，那么遍历字符串列表的其他选项是使用“while”或“until”循环。
Is it the case that you are wanting to write a bash script that can be executed as follows?
是不是想写一个可以执行如下的bash脚本？
$ cowsay-loop foo bar buzz
$ cowsay-loop foo bar buzz
