使用grep和sed将一个字符串替换为另一个字符串 [英] Using grep and sed to replace one string with another

问题描述

我想用另一个文件中的字符串替换一个文件中的一个字符串。虽然我对这些命令没有经验，但我希望grep和sed的组合能够做到最好。

是什么让这更复杂一点是我不知道这两个字符串是什么（我试图自动替换我的文档中的版本号）。我知道在这两种情况下，我在寻找的字符串（比如2.3.4）前面都有version：。

所以我可以说'look在版本：（让我们称之为string1）之后为单词（或者其他可能的行）或者其他可能的文件（在string1中），然后在另一个文件中执行相同的操作（给出string2），并用string2替换string1。

以下是一些示例文本文件： b
$ b file1.txt

这是一个包含

更新版本号的文件。

版本：2.3.4

这里是一个包含更多信息的字符串

file2.txt
$ b

这是一个配置文件<
它可以包含一个旧的版本号

版本：2.3.2

请更新这个

因此，file2.txt的预期输出将变为：

file2.txt

< blockquote>

这是一个配置文件

它可以继续一个旧版本号

版本：2.3.4

请更新这个

谢谢

解决方案

假设您有一个 sed ，它支持选项，

  sed -i's / version：。* / version ：1.2.3 /'file1 file2 file3 ... 
  

您可能想要调整正则表达式通配符; 。* 通过行尾匹配，而 [。0-9] * 匹配最长的可能序列点和数字。您可能还想允许周围空白的变化...但是，因为这可能是本网站上10％的常见问题解答之一，请在此处查找类似问题。

从file1中获取替换字符串并将其应用于file2，file3等，类似于

  new = $（ sed -n's / version：// p'file1）
＃为了展开$ new 
 sed -is / version：[.0-9]，使用双引号，而不是单引号。 * / version：$ new /file2 file3 ... 
  

第一个 sed 调用将只打印找到并删除version：的行（用空字符串替换）。据推测，文件中只会有这样一行。将输出管道输出到 head -n 1 或 uniq 或其他东西，或者找到/创建更详细的 sed 脚本。

您通常在文字字符串周围使用单引号，但由于您不需要文字 $ new 在替换中，我们使用双引号，它允许shell在引用的字符串中执行变量替换（以及其他一些替换，我们不在此处介绍）。

I'd like to replace one string from one file with a string from another file. Though I'm not experienced with these commands, I expect some combination of grep and sed would do it best.

What makes this a bit more complicated is that I don't know what either string is (I'm trying to automate replacing the version number on my documentation). I do know that in both cases the string I'm looking for (say "2.3.4") is preceded by "version:"

So can I say 'look for word (or rest of line or whatever is possible) after "version:" (let's call it string1) and do the same in another file (giving string2) and replace string string1 with string2.

Here are some example text files:

file1.txt

This is a file containing
the updated version number.
version: 2.3.4
here is a string with more info

file2.txt

This is a configuration file
It could contain an old version number
version: 2.3.2
Please update this

So the expected output for file2.txt would become:

file2.txt

This is a configuration file
It could contain an old version number
version: 2.3.4
Please update this

Thanks

解决方案

Provided you have a sed which supports the -i option,

sed -i 's/version: .*/version: 1.2.3/' file1 file2 file3 ...

You may want to tweak the regex wildcard; .* matches through the end of the line, whereas [.0-9]* matches the longest possible sequence of dots and digits. You might also want to permit for variations in surrounding whitespace ... But since this is probably among the top 10% FAQs on this site, go look for similar questions at this point.

To obtain the replacement string from file1 and apply it to file2, file3, etc, something like

new=$(sed -n 's/version: //p' file1)
# Use double quotes, not single, in order to expand $new
sed -i "s/version: [.0-9]*/version: $new/" file2 file3 ...

The first sed invocation will only print lines on which "version: " was found and removed (replaced with an empty string). Presumably there will only be one such line in the file. Pipe the output to head -n 1 or uniq or something, or find / create a more elaborate sed script.

You normally use single quotes around literal strings, but since you don't want a literal $new in the replacement, we use double quotes, which allow the shell to perform variable replacement (and a number of other substitutions we don't go into here) in the quoted string.

这篇关于使用grep和sed将一个字符串替换为另一个字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！