了解空格和 xargs

发布于 2024-10-24 03:53:48 字数 764 浏览 2 评论 0原文

我了解到，当将 find 与 xargs 一起使用时，建议使用 -print0 和 -0 参数使带有空格的文件名能够正常工作。

现在我有一个名为 patterns 的文件，其中包含以下内容

a a a
b b b

，并且我有一个名为 text 的文件，其中包含以下内容

a
b b b

当我运行以下命令时，

cat patterns| xargs -ipattern grep pattern text

我得到

b b b

的结果是 xargs知道寻找 aa a 和 bb b 而不是 a、a、a >、b、b、b。

我的问题是为什么上面的例子没有任何问题？我认为它会寻找 a、a、a、b、b , b 并返回 text 中的两行。

我缺少什么？

原文

I've learned that when using find with xargs, it's advisable to use the -print0 and -0 arguments for file names with spaces to work correctly.

Now I have the following file named patterns with the following content

a a a
b b b

and I have the file named text with the following content

a
b b b

When I run the following command,

cat patterns| xargs -ipattern grep pattern text

I get

b b b

which means that xargs knew to look for a a a and b b b instead of a, a, a, b, b, b.

My question is why isn't there any problems in the example above? I thought it would look for a, a, a, b, b, b and return both lines in text.

What am I missing?

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笑着哭最痛 2024-10-31 03:53:48

-i 和 -I 将其从使用（可能带引号的）空格分隔的字符串更改为行。引用 man xargs：

   -I replace-str
          Replace occurrences of replace-str in the initial-arguments with  names  read  from
          standard  input.   Also,  unquoted blanks do not terminate input items; instead the
          separator is the newline character.  Implies -x and -L 1.

   --replace[=replace-str]
   -i[replace-str]
          This option is a synonym for -Ireplace-str if replace-str  is  specified,  and  for
          -I{} otherwise.  This option is deprecated; use -I instead.

当您在默认（即不是 -I）模式下使用文件名时，您需要保护空格、制表符和（而不是像这样的文件名）都是个好主意）换行符；因此-0。

-i and -I change it from using (possibly quoted) whitespace-separated strings to lines. Quoting man xargs:

   -I replace-str
          Replace occurrences of replace-str in the initial-arguments with  names  read  from
          standard  input.   Also,  unquoted blanks do not terminate input items; instead the
          separator is the newline character.  Implies -x and -L 1.

   --replace[=replace-str]
   -i[replace-str]
          This option is a synonym for -Ireplace-str if replace-str  is  specified,  and  for
          -I{} otherwise.  This option is deprecated; use -I instead.

When you're working with filenames in default (i.e. not -I) mode, you need to protect spaces, tabs, and (not that filenames like this are ever a good idea) newlines; hence -0.

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