find中的-prune选项有什么作用？ [英] What does -prune option in find do?

问题描述

我可以看到 find 的-prune无法正常工作。我想 -nameefence *-prune 选项应选择（或查找）除名称 efence * 对吗？

或者我的理解错了吗？

我执行的命令是：
find * -maxdepth 0 -nameefence *-prune

期望 ：选择当前目录中的所有文件（ maxdepth 0 ），除了名称* efence。

请帮我了解 -prune

解决方案

  find * -maxdepth 0 -nameefence *-prune -o -print 
  

如果没有指定其他选项，则 prune 选项不会打印匹配的文件但是） find 从递归到匹配的目录中找到



编辑添加解释：

find 表达式区分 tests 和动作。从 man找到：

表达式由选项组成操作
，而不是处理一个特定的文件，并且总是返回true），
tests（返回true或者false的值）和action（具有
的副作用并且返回true或虚假值），全部由运营商分隔。

如果表达式不包含除<在表达式为真的所有文件上执行code> -prune ， -print 。

所以 -prune 是一个副作用是 find 不会递归到与前面的测试相匹配的子目录中（在您的情况下， -maxdepth 0 -nameefence *） 。但是就表达式的真值而言，它相当于只有

  find * -maxdepth 0 -nameefence *-true 
  

由于您没有指定任何其他操作，所以 -print 是假定的（这个假设总是存在的，因为它允许你输入例如 find。-name* .java而不是 find。-name* .java-print ）。

希望是有道理的。在另一个线程接受的答案谈论同样的事情。

I can see the -prune of find not working correctly. I guess -name "efence*" -prune option should select (or find) all files except the one with name efence* right?

Or am i wrong in my understanding?

The command i executed: find * -maxdepth 0 -name "efence*" -prune

Expectation: Select all files at current directory (maxdepth 0) except one with name *efence.

Please help me to understand -prune

解决方案

Try

find * -maxdepth 0 -name "efence*" -prune -o -print

The prune option does print matching files, if no other options are specified (it still prevents find from recursing into matching directories, however).

Edited to add explanation:

find expressions distinguish between tests and actions. From man find:

The expression is made up of options (which affect overall operation rather than the processing of a specific file, and always return true), tests (which return a true or false value), and actions (which have side effects and return a true or false value), all separated by operators. -and is assumed where the operator is omitted.

If the expression contains no actions other than -prune, -print is performed on all files for which the expression is true. [my emphasis]

So -prune is an action which has the side effect that find will not recurse into subdirectories which match the preceding test (in your case, -maxdepth 0 -name "efence*"). But in terms of the truth-value of the expression, it's equivalent to just having

find * -maxdepth 0 -name "efence*" -true

and since you didn't specify any other action, -print is assumed (this assumption is always present as it allows you to type e.g. find . -name "*.java" instead of find . -name "*.java" -print).

Hope that makes sense. The accepted answer at the other thread talks about the same thing.

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