两个分隔符之间的grep子字符串 [英] grep substring between two delimiters

问题描述

我有很多bash脚本，它们使用grep中的perl表达式来提取两个定界符之间的子字符串.示例:

I have a lot of bash scripts that use perl expressions within grep in order to extract a substring between two delimiters. Example:

echo BeginMiddleEnd | grep -oP '(?<=Begin).*(?=End)'

问题是，当我将这些脚本移植到运行busybox的平台时，集成" grep无法识别-P开关.有没有一种干净的方法可以使用grep和regular expressions来做到这一点?

The problem is, when I ported these scripts to a platform running busybox, 'integrated' grep does not recognize -P switch. Is there a clean way to do this using grep and regular expressions?

该平台上没有perl，sed或awk.这是一个轻量级的linux.

There is no perl, sed or awk on that platform. It's a lightweight linux.

推荐答案

假设每行最多出现一次，则可以使用

Assuming there's no more than one occurrence per line, you can use

sed -nr 's/.*Begin(.*)End.*/\1/p'

使用grep和非贪婪量词，您还可以每行打印多个.

With grep and non-greedy quantifier you could also print more than one per line.

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