Using Grep with Context Options: A Complete Guide

You can use grep along with -A (after), -B (before), or -C (context) options to capture lines containing a string and either the line before or after.

Example:

Let’s assume you’re searching for the string pattern in a file called file.txt.

1. Line containing the pattern + line after (-A):

1
grep -A 1 "pattern" file.txt

This command prints the line containing pattern and the next line after it. 1 represents the number of lines to show after the match.

2. Line containing the pattern + line before (-B):

1
grep -B 1 "pattern" file.txt

This command prints the line containing pattern and the previous line before it. 1 represents the number of lines to show before the match.

3. Line containing the pattern + one line before and after (-C):

1
grep -C 1 "pattern" file.txt

This command prints the line containing pattern, one line before, and one line after the match. 1 represents the number of lines before and after the match.

Examples:

For example, given this content in file.txt:

1
Line 1
2
Line 2
3
Pattern Match Here
4
Line 4
5
Line 5
6
Line 6

• grep -A 1 "Pattern" file.txt would output:

  1
  Pattern Match Here
  2
  Line 4

• grep -B 1 "Pattern" file.txt would output:

  1
  Line 2
  2
  Pattern Match Here

• grep -C 1 "Pattern" file.txt would output:

  1
  Line 2
  2
  Pattern Match Here
  3
  Line 4

These options allow you to customize how much context you want around the matching lines.

This article was written by Qwen, based on content from: ChatGPT