如何使用 >在 xargs 命令中? [英] How to use > in an xargs command?

问题描述

我想找到一个 bash 命令，它可以让我 grep 目录中的每个文件，并将该 grep 的输出写入一个单独的文件.我的猜测是做这样的事情

I want to find a bash command that will let me grep every file in a directory and write the output of that grep to a separate file. My guess would have been to do something like this

ls -1 | xargs -I{} "grep ABC '{}' > '{}'.out"

但是，据我所知，xargs 不喜欢双引号.但是，如果我删除双引号，则该命令会将整个命令的输出重定向到名为{}".out 的单个文件，而不是一系列单独的文件.

but, as far as I know, xargs doesn't like the double-quotes. If I remove the double-quotes, however, then the command redirects the output of the entire command to a single file called '{}'.out instead of to a series of individual files.

有谁知道使用 xargs 做到这一点的方法吗?我只是以这个 grep 场景为例来说明我的 xargs 问题，因此任何不使用 xargs 的解决方案都不适用于我.

Does anyone know of a way to do this using xargs? I just used this grep scenario as an example to illustrate my problem with xargs so any solutions that don't use xargs aren't as applicable for me.

推荐答案

不要犯这样的错误:

sh -c "grep ABC {} > {}.out"

这在很多情况下都会中断，包括时髦的文件名，并且不可能正确引用.您的 {} 必须始终是命令的一个完全独立的参数，以避免代码注入错误.你需要做的是:

This will break under a lot of conditions, including funky filenames and is impossible to quote right. Your {} must always be a single completely separate argument to the command to avoid code injection bugs. What you need to do, is this:

xargs -I{} sh -c 'grep ABC "$1" > "$1.out"' -- {}

适用于 xargs 以及 find.

顺便说一句，不要在没有 -0 选项的情况下使用 xargs(除非用于非常少见且受控的一次性交互式使用，您不必担心破坏数据).

By the way, never use xargs without the -0 option (unless for very rare and controlled one-time interactive use where you aren't worried about destroying your data).

也不要解析ls.曾经.使用通配符或 find 代替:http://mywiki.wooledge.org/ParsingLs

Also don't parse ls. Ever. Use globbing or find instead: http://mywiki.wooledge.org/ParsingLs

对于需要递归的所有内容使用 find，对于其他所有内容使用带有 glob 的简单循环:

Use find for everything that needs recursion and a simple loop with a glob for everything else:

find /foo -exec sh -c 'grep "$1" > "$1.out"' -- {} ;

或非递归:

for file in *; do grep "$file" > "$file.out"; done

注意引号的正确使用.

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