Mastering Grep: 12 Powerful Linux Search Techniques

1. List installed Python packages

List all Python‑related RPM packages on the system.

# rpm -qa | grep -i python

Sample output includes entries such as python-kitchen-1.1.1-5.el7.noarch , python2-pip-8.1.2-14.el7.noarch , and many others.

2. Search and filter files

Remove all comment lines from an Nginx configuration file.

# grep -v "#" /etc/nginx/nginx.conf

The -v option inverts the match, printing only lines that do not contain the # character.

3. Find only .mp3 files with multiple filters

Locate all .mp3 files, keep only those containing "jaychou" in the path, and exclude those containing "七里香".

# find . -name "*.mp3" | grep -i jaychou | grep -vi "七里香"

4. Show lines before or after a match

Use -A to display a number of lines after a match and -B for lines before a match.

# ifconfig | grep -A 4 eth0
# ifconfig | grep -B 2 UP

5. Print surrounding lines

The -C option prints a symmetric number of context lines around each match.

# ifconfig | grep -C 2 lo

6. Count matches

Count how many times a pattern appears without piping to wc .

# ifconfig | grep -c inet6

7. Search files with line numbers

Show the line numbers of occurrences, useful for debugging compilation errors.

# grep -n "main" setup..py

8. Recursive search in all directories

Search for a string throughout the current directory tree.

# grep -r "function" *

9. Search whole‑word patterns

Match only whole words using -w . For example, searching for "RUNNING" returns matching lines, while searching for "RUN" does not because it is not a whole word.

# ifconfig | grep -w "RUNNING"
# ifconfig | grep -w "RUN"

10. Search inside compressed files

zgrep works like grep on .gz files, using the same options.

# zgrep -i error /var/log/rumenz.gz

11. Use extended regular expressions

egrep (or grep -E ) enables additional metacharacters such as + , ? , | , and parentheses.

# grep -E "pattern" file

12. Search fixed‑string patterns

fgrep (equivalent to grep -F ) searches for literal strings without interpreting regular expressions, offering faster performance for exact matches.

# fgrep strcpy *.c