不区分大小写的搜索并替换为sed [英] Case-insensitive search and replace with sed

问题描述

我正在尝试使用SED从日志文件中提取文本.我可以轻松进行搜索和替换:

I'm trying to use SED to extract text from a log file. I can do a search-and-replace without too much trouble:

sed 's/foo/bar/' mylog.txt

但是，我想使搜索不区分大小写.从我搜索过的内容来看，将i附加到命令末尾似乎可以正常工作:

However, I want to make the search case-insensitive. From what I've googled, it looks like appending i to the end of the command should work:

sed 's/foo/bar/i' mylog.txt

但是，这给了我一条错误消息:

However, this gives me an error message:

sed: 1: "s/foo/bar/i": bad flag in substitute command: 'i'

这里出了什么问题，我该如何解决?

What's going wrong here, and how do I fix it?

推荐答案

要明确:在 macOS 上-自Mojave(10.14)起- sed-即 BSD 实现-不支持不区分大小写的匹配-难以置信，但确实如此. 以前接受的答案(其本身显示了 GNU sed命令)之所以获得该状态，是因为评论中提到的基于perl的解决方案.

To be clear: On macOS - as of Mojave (10.14) - sed - which is the BSD implementation - does NOT support case-insensitive matching - hard to believe, but true. The formerly accepted answer, which itself shows a GNU sed command, gained that status because of the perl-based solution mentioned in the comments.

要使 Perl解决方案也可以通过UTF-8与外国字符一起使用，请使用类似以下内容的东西:

To make that Perl solution work with foreign characters as well, via UTF-8, use something like:

perl -C -Mutf8 -pe 's/öœ/oo/i' <<< "FÖŒ" # -> "Foo"

• -C假设当前语言环境是基于UTF-8的，打开了对流和文件的UTF-8支持.
• -Mutf8告诉Perl将源代码解释为UTF-8(在这种情况下，是传递给-pe的字符串)-这是更冗长的-e 'use utf8;'.的等价形式. ^{谢谢，马克·里德}
• -C turns on UTF-8 support for streams and files, assuming the current locale is UTF-8-based.
• -Mutf8 tells Perl to interpret the source code as UTF-8 (in this case, the string passed to -pe) - this is the shorter equivalent of the more verbose -e 'use utf8;'.^{Thanks, Mark Reed}

(请注意，使用awk也不可行，就像在macOS上的awk(即 BWK awk ，也称为 BSD awk )似乎完全不了解语言环境-它的tolower()和toupper()函数会忽略外来字符(并且sub()/gsub()开头没有区分大小写的标志).

(Note that using awk is not an option either, as awk on macOS (i.e., BWK awk, a.k.a. BSD awk) appears to be completely unaware of locales altogether - its tolower() and toupper() functions ignore foreign characters (and sub() / gsub() don't have case-insensitivity flags to begin with).)

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