巴什＆QUOT; DIFF＆QUOT;使用正则表达式时，忽略实用的文件显示不同 [英] Bash "diff" utility showing files as different when using a regex Ignore

问题描述

我尝试使用此处介绍的是bash工具差别：的http：// ss64 .COM /庆典/ diff.html 。请注意，我用的是bash实用的Windows的移植版本，但不应该作出任何区别。

I'm trying to use the bash utility "diff" that is documented here: http://ss64.com/bash/diff.html. Note that I'm using a windows-ported version of the bash utility, but that shouldn't make any difference.

我有两个文件，​​regex_test_1.txt和regex_test_2.txt具有以下内容：

I have two files, regex_test_1.txt and regex_test_2.txt that have the following contents:

regex_test_1.txt：

regex_test_1.txt:

// $Id: some random id string $ more text

text that matches

regex_test_2.txt：

regex_test_2.txt:

// $Id: some more random id string $ more text

text that matches

我想而忽略符合此正则表达式的行差异比较这些文件：

I am trying to diff these files while ignoring any lines that fit this regex:

.*\$(Id|Header|Date|DateTime|Change|File|Revision|Author):.*\$.*

然而，当我运行差异，并告诉它忽略匹配使用-i参数此正则表达式的线条，这是输出：

However, when I run diff and tell it to ignore lines matching this regex using the -I argument, this is the output:

C:\Users\myname\Documents>diff -q -r -I ".*\$(Id|Header|Date|DateTime|Change|File|Revision|Author):.*\$.*" regex_test_1.txt regex_test_2.txt
Files regex_test_1.txt and regex_test_2.txt differ

我期望它应该找到无显着差异（和报告无）。为什么会找到这些文件是不同的？

I expect that it should find no differences (and report nothing). Why is it finding these files to be different?

推荐答案

这是因为差异使用基本正则表达式语法，其中的某些正则表达式的元字符失去其特殊意义：

It's because diff uses basic regex syntax, wherein certain regex metacharacters lose their special meaning:

在基本的正前pressions的元字符？+，{，|，（和）失去了它们的特殊意义;改用反斜杠的版本 \\？\\ + \\ {，\\ |，\\（和\\）

In basic regular expressions the meta-characters ?, +, {, |, (, and ) lose their special meaning; instead use the backslashed versions \?, \+, \{, \|, \(, and \).

这应该工作：

.*\$\(Id\|Header\|Date\|DateTime\|Change\|File\|Revision\|Author\):.*\$.*

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