如何刷出可以改变的子字符串？ [英] How to grep out substring which can change?

问题描述

基本上我有一个非常大的文本文件，每一行都包含

  tag = yyyyy; id = xxxxx; db_ref = zzzzz ; 
  

我想要的是刷出id，但id可以在长度和形式上改变，I想知道是否有可能使用grep -o然后grep为id =，然后提取它后面的所有内容直到分号？

解决方案

您可以这样做：

  $ grep -o'id = [^;] *'文件
  

如果您不想包含 id = 部分你可以使用积极的后视：

  $ grep -Po'（？< = id =）[^;] *'file 
  

Basically I have a very large text file and each line contains

tag=yyyyy;id=xxxxx;db_ref=zzzzz; 

What I want is to grep out the id, but the id can change in length and form, I was wondering if its possible to use grep -o and then grep for "id=" then extract everything that comes after it until the semicolon?

解决方案

You could do:

$ grep -o 'id=[^;]*' file

And if you don't want to inlcude the id= part you can using positive look-behind:

$ grep -Po '(?<=id=)[^;]*' file

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