grep in Bash

grep with context

grep -B 10 -A 10 "Refresh" structure.json

Here -B = before, -A = after.

grep -C 10 "Refresh" structure.json

-C 10 → shows 10 lines before and 10 lines after the matching line.

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grep all files in a directory

grep -n "a word" *

To search recursively (including subdirectories):

grep -Rni "a word" *

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Useful Extra Options

Only certain files:

grep -ni "a word" *.log

Show filename + line number + matching line:

grep -Hn "a word" *

Case-insensitive search:

grep -Hin "a word" *

If some files are binary (to get rid of noisy output):

grep -HinI "a word" *

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Flag	Meaning	What it does
-H	With filename	Always prints the filename where the match was found
-i	Ignore case	Matches a word, A Word, A WORD, etc.
-n	Line number	Shows the line number containing the match
-I	Ignore binary files	Skips files that grep considers binary
*	Wildcard	Passes all files in the current directory to grep

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Search a term in any files on a folder

Use grep -Ri "search_term"

• R - recursive
• i - ignore case

Example: grep -Ri "ssh"

output:

Miscellaneous.md:Example: `grep -R "ssh"`

Problem_Fixing.md:_through Secure Socket Shell(SSH)**_

Fish_Abbreviations.md:### SSH Commands

Fish_Abbreviations.md:* sr - `ssh appuser@192.168.1.230`

Fish_Abbreviations.md:* sl - `ssh appuser@192.168.1.228`

Example:

Check Port details

ss -tuln | grep port_number

• ss: Utility to dump socket statistics (replaces the older netstat).

• Flags: -tuln

  • -t: Show TCP sockets
  • -u: Show UDP sockets
  • -l: Show listening sockets only
  • -n: Show numerical addresses (don’t resolve hostnames/services)

• | grep port_number: Filters the output to lines containing the specified port_number