grep -A< num>直到一个字符串 [英] grep -A <num> until a string

问题描述

假设我们有一个包含以下内容的文件：

  chapter 1 blah blah 
 blah num blah num 
 num blah num blah 
 ... 
 blah num 
 chapter 2 blah blah 
  

，我们希望grep这个文件，所以我们从第1章blah blah 到 blah num
（下一章前一行）。

b $ b

1. 说明字符串第1章等等等等


2. 之后还有另一个以章节开始的行





一个虚拟的方法是

  grep -A< num> -i第1章< file> 
  

足够大< num> so整个章节将在其中。

解决方案

使用 awk $ b

  awk'/ chapter / {f = 0} / chapter 1 / {f = 1} f'file 
 Chapter 1 blah blah 
 blah num blah num 
 num blah num blah 
 ... 
 blah num 
  

如果标记 f 为真，它将打印行。

第一章和下一章章节来更改标志。



---





您可以使用范围 awk ，但是如果您有其他东西需要测试，它的灵活性会降低。

  awk'/ chapter 1 /，/ chapter [^ 1] / {if（！/ chapter [^ 1] /）print}'file 
 chapter 1 blah blah 
 blah num blah num 
 num blah num blah 
 ... 
 blah num 
  




assuming that we have a file containing the following:

chapter 1 blah blah
blah num blah num
num blah num blah
...
blah num
chapter 2 blah blah

and we want to grep this file so we take the lines from chapter 1 blah blah to blah num (the line before the next chapter).

The only things we know are

1. the stating string chapter 1 blah blah
2. somewhere after that there is another line starting with chapter

a dummy way to do this is

grep -A <num> -i "chapter 1" <file>

with large enough <num> so the whole chapter will be in it.

解决方案

This is easy to do with awk

awk '/chapter/ {f=0} /chapter 1/ {f=1} f' file
chapter 1 blah blah
blah num blah num
num blah num blah
...
blah num

It will print the line if flag f is true.
The chapter 1 and next chapter to changes the flag.

---

You can use range with awk but its less flexible if you have other stuff to test.

awk '/chapter 1/,/chapter [^1]/ {if (!/chapter [^1]/) print}' file
chapter 1 blah blah
blah num blah num
num blah num blah
...
blah num

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