如何仅使用grep/sed提取子字符串和数字 [英] how to extract substring and numbers only using grep/sed

问题描述

我有一个同时包含文本和数字的文本文件，我想使用grep仅提取我需要的数字，例如，给定一个文件，如下所示:

I have a text file containing both text and numbers, I want to use grep to extract only the numbers I need for example, given a file as follow:

miss rate 0.21  
ipc 222  
stalls n shdmem 112

所以说我只想提取未命中率的数据，即 0.21 .我该如何使用grep或sed?另外，我需要一个以上的数字，不仅是 miss rate 之后的数字.也就是说，我可能想同时获得 0.21 和 112 .输出示例如下:

So say I only want to extract the data for miss rate which is 0.21. How do I do it with grep or sed? Plus, I need more than one number, not only the one after miss rate. That is, I may want to get both 0.21 and 112. A sample output might look like this:

0.21 222 112

因为我需要数据以备后用.

Cause I need the data for later plot.

推荐答案

请改用 awk :

awk '/^miss rate/ { print $3 }' yourfile

仅使用grep即可完成此操作，您需要使用非标准扩展名，例如此处使用PCRE(-P)和正向后置(?< = ..)且仅匹配(-o)的GNU grep.

To do it with just grep, you need non-standard extensions like here with GNU grep using PCRE (-P) with positive lookbehind (?<=..) and match only (-o):

grep -Po '(?<=miss rate ).*' yourfile

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