How do I run this script?

Save the grep examples as search.sh, chmod +x search.sh, then run ./search.sh or use the grep commands directly in your terminal.

Does this work on macOS?

Yes. grep is pre-installed on macOS. Use grep -r instead of grep -R on older macOS versions if needed.

Search Files for Text with grep

Q: How do I search for text inside files in Linux?

Use grep -rn "pattern" /path/to/dir to search recursively with line numbers. Add --include="*.ext" to filter by file type.

Q: How do I make grep case insensitive?

Add the -i flag: grep -ri "pattern" /path/to/dir searches without case sensitivity.

The Script

This covers the most useful grep patterns. Paste the one you need and change the search term and path.

bash

#!/bin/bash
# Search files for text — grep reference
# Replace KEYWORD and SEARCH_DIR with your values
#
# USAGE: ./grep-search.sh
# REQUIRES: grep (pre-installed on Linux/macOS)

KEYWORD="TODO"          # ← what to search for
SEARCH_DIR="$HOME"    # ← where to search
FILE_TYPE="*.txt"     # ← file types to include

echo "Searching for '$KEYWORD' in $SEARCH_DIR..."
echo "────────────────────────────────────────"

grep -rn "$KEYWORD" "$SEARCH_DIR" \
  --include="$FILE_TYPE" \
  --color=auto

COUNT=$(grep -rc "$KEYWORD" "$SEARCH_DIR" \
  --include="$FILE_TYPE" 2>/dev/null \
  | grep -v ":0$" | wc -l)

echo "────────────────────────────────────────"
echo "Found in $COUNT file(s)"

What this does

grep -rn searches recursively (-r) through all subdirectories and shows line numbers (-n) for each match. --include filters to a specific file type. --color=auto highlights your keyword in the output so it's easy to scan.

Step-by-Step: The Commands You'll Use Daily

Step 1 — Search a single file

The simplest form: search one file for one term.

bash

grep "ERROR" /var/log/app.log

Every line containing "ERROR" prints to your terminal. Nothing else. Fast.

Step 2 — Add line numbers (-n)

bash

grep -n "ERROR" /var/log/app.log

# Output:
# 42: ERROR: connection refused
# 87: ERROR: disk write failed

Now you know exactly which line to jump to in your editor.

Step 3 — Search recursively across a whole folder (-r)

bash

grep -rn "TODO" ~/projects/

# Output includes filename, line number, and the matching line:
# ~/projects/api/routes.py:14:  # TODO: add auth check
# ~/projects/api/models.py:88:  # TODO: validate input

-rn is your default combination

You'll type grep -rn "keyword" /path more than almost any other command. The r searches all subdirectories, the n gives you line numbers. Memorise this one first.

Step 4 — Filter by file type (--include)

bash

# Search only .log files
grep -rn "CRITICAL" /var/log --include="*.log"

# Search only Python files
grep -rn "import os" ~/projects --include="*.py"

# Search multiple file types
grep -rn "api_key" . --include="*.py" --include="*.env"

Step 5 — Case insensitive search (-i)

bash

# Matches: error, ERROR, Error, eRrOr
grep -rni "error" /var/log --include="*.log"

grep Flags Reference

Flag	What it does	Example
-r	Recursive — search all subdirectories	grep -r "term" /folder
-n	Show line numbers in output	grep -n "term" file.txt
-i	Case insensitive match	grep -i "error" file.log
-l	Show only filenames, not the matching lines	grep -rl "TODO" ~/projects
-c	Count of matching lines per file	grep -rc "error" /var/log
-v	Invert — show lines that do NOT match	grep -v "DEBUG" app.log
-w	Match whole words only	grep -w "log" file.txt
-A 3	Show 3 lines after each match (context)	grep -A 3 "ERROR" app.log
-B 3	Show 3 lines before each match	grep -B 3 "ERROR" app.log
--include	Limit search to matching filenames	grep -r "term" . --include="*.py"
--exclude	Skip files matching pattern	grep -r "term" . --exclude="*.min.js"

Real-World Examples

Find all TODO comments across a codebase

bash

grep -rn "TODO\|FIXME\|HACK" ~/projects --include="*.py"

Scan logs for errors in the last hour

bash

# Find ERROR lines and show 2 lines of context around each
grep -n -A 2 -B 2 "ERROR" /var/log/app.log

Check if a config file contains a specific setting

bash

# Returns the line if found, nothing if not
grep "PermitRootLogin" /etc/ssh/sshd_config

Count how many files in a project contain a term

bash

# -l lists filenames only, wc -l counts them
grep -rl "api_key" . | wc -l

Search and exclude a directory (e.g. node_modules)

bash

grep -rn "password" . \
  --include="*.js" \
  --exclude-dir="node_modules" \
  --exclude-dir=".git"

Always exclude node_modules and .git

Searching a project without excluding node_modules or .git will flood your results with thousands of irrelevant matches and run significantly slower. Add --exclude-dir=node_modules --exclude-dir=.git to every recursive grep on a project folder.

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Common Mistakes

Forgetting -r on a folder

Running grep "term" /var/log without -r will error with "Is a directory." You need grep -r "term" /var/log to search inside a folder recursively.

Special characters in your search term

Characters like ., *, [, and ( are regex special characters. If you're searching for them literally, either escape them with a backslash (\.) or use grep -F (fixed string mode) to treat the term as plain text, not a regex pattern.

Understanding the Commands

Command	What it does
grep "term" file	Prints every line in file containing "term"
grep -r "term" dir	Recursively searches all files in dir and subdirectories
grep -n "term" file	Adds line numbers to each matching line in output
grep -l "term" dir	Lists only filenames that contain a match — no line content
grep -c "term" file	Counts the number of matching lines in file
grep -v "term" file	Prints every line that does NOT contain "term" (invert match)
--include="*.ext"	Restricts search to files matching the glob pattern
--exclude-dir=name	Skips a directory entirely during recursive search

Frequently Asked Questions

How do I search for text inside files in Linux?

Use grep "search term" filename for a single file, or grep -rn "search term" /folder to search every file in a folder recursively. The -n flag adds line numbers so you can jump straight to each match.

How do I search multiple files with grep?

Use grep -r "term" /folder — the -r flag makes grep recurse into all subdirectories automatically. Add --include="*.py" to restrict results to a specific file type.

How do I make grep case insensitive?

Add the -i flag: grep -i "error" logfile.txt. This matches ERROR, error, Error, and any mixed-case variant.

How do I search for a word in a specific file type?

Use grep -rn "term" /folder --include="*.py". You can stack multiple --include flags to search several file types at once.

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Search Files for Text with grep

The Script

Step-by-Step: The Commands You'll Use Daily

Step 1 — Search a single file

Step 2 — Add line numbers (-n)

Step 3 — Search recursively across a whole folder (-r)

Step 4 — Filter by file type (--include)

Step 5 — Case insensitive search (-i)

grep Flags Reference

Real-World Examples

Find all TODO comments across a codebase

Scan logs for errors in the last hour

Check if a config file contains a specific setting

Count how many files in a project contain a term

Search and exclude a directory (e.g. node_modules)

Common Mistakes

Understanding the Commands

Frequently Asked Questions

How do I search for text inside files in Linux?

How do I search multiple files with grep?

How do I make grep case insensitive?

How do I search for a word in a specific file type?

Related Snippets

Frequently Asked Questions