Grep中'word'的含义 [英] The meaning of 'word' in Grep

问题描述

 >符号\<和\>分别匹配
>的空字符串。一个词的开始和结束。 
  

这里是什么意思？

我知道这个词是在-w 中定义的，但这里证明了它在这种情况下有不同的含义：

如果文件'test'包含 hi / 和I grep -w'hi /'test ，我得到一个匹配，
但是如果我 grep'hi / \>'test ，我不会。

解决方案

一个单词的开头是一个单词字符（一个字母，数字或下划线），前面没有另一个单词字符，而单词的末尾是一个单词字符，不是之后是另一个单词字符。一个单词就是一系列单词字符。

原因 hi / \> doesn 't match hi / 是因为 \> 前面有一个非单词字符（ / ），因此不能是单词结尾的位置。

In the man page for grep it says that:

> The symbols \< and \> respectively match the empty string at the
> beginning and end of a word.

What is meant here by word?

I know that word is defined in -w, but here is the proof that it has a different meaning in this context:

If file 'test' contains hi/, and I grep -w 'hi/' test, I get a match, but if I grep 'hi/\>' test, I don't.

解决方案

The beginning of a word is a word character (a letter, number, or underscore) that is not preceded by another word character, and the end of a word is a word character that is not followed by another word character. A "word" is then just a series of word characters.

The reason hi/\> doesn't match hi/ is because the \> is preceded by a non-word character (/), and so that can't be the location of an end-of-word.

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