File Search

Overview

In Linux systems, we often need to find files and directories. This chapter introduces several commonly used file search tools: find, locate, which, whereis, etc.

find Command

find is the most powerful file search command that can search for files in real-time based on various conditions.

Basic Syntax

bash

find [search_path] [conditions] [actions]

Search by Name

bash

# Search by filename
$ find /home -name "file.txt"

# Case-insensitive
$ find /home -iname "file.txt"

# Use wildcards
$ find /home -name "*.txt"
$ find /home -name "file?.txt"

# Search for specific directory names
$ find /home -name "project*" -type d

Search by Type

bash

# Search only for files
$ find /home -type f

# Search only for directories
$ find /home -type d

# Search only for symbolic links
$ find /home -type l

# Search for empty files
$ find /home -type f -empty

# Search for empty directories
$ find /home -type d -empty

File Types

Type	Description
f	Regular file
d	Directory
l	Symbolic link
b	Block device
c	Character device
s	Socket
p	Pipe

Search by Size

bash

# Files larger than 100MB
$ find /home -size +100M

# Files smaller than 1KB
$ find /home -size -1k

# Files exactly 100 bytes
$ find /home -size 100c

# Files between 10MB and 100MB
$ find /home -size +10M -size -100M

Size Units

Unit	Description
c	Bytes
k	KB
M	MB
G	GB

Search by Time

bash

# Files modified in the last 7 days
$ find /home -mtime -7

# Files modified 7 days ago
$ find /home -mtime +7

# Files modified exactly 7 days ago
$ find /home -mtime 7

# Files modified in the last 60 minutes
$ find /home -mmin -60

# Files accessed in the last 24 hours
$ find /home -atime -1

# Files with status changed in the last 7 days
$ find /home -ctime -7

Time Types

Option	Description
-mtime	Modification time (content)
-atime	Access time
-ctime	Status change time (permissions, ownership)
-mmin	Modification time (minutes)
-amin	Access time (minutes)
-cmin	Status change time (minutes)

Search by Permissions

bash

# Find files with permissions 644
$ find /home -perm 644

# Find files with at least specified permissions
$ find /home -perm -644

# Find files with any of the specified permissions
$ find /home -perm /644

# Find SUID files
$ find /usr -perm -4000

# Find writable files
$ find /home -perm -222

Search by Ownership

bash

# Search by user
$ find /home -user maxwell

# Search by group
$ find /home -group developers

# Find files without an owner
$ find /home -nouser

# Find files without a group
$ find /home -nogroup

Combine Conditions

bash

# AND (default)
$ find /home -name "*.txt" -size +1M

# OR
$ find /home -name "*.txt" -o -name "*.md"

# NOT
$ find /home ! -name "*.txt"

# Use parentheses for grouping (needs escaping)
$ find /home \( -name "*.txt" -o -name "*.md" \) -size +1M

Limit Search Depth

bash

# Search only in current directory
$ find /home -maxdepth 1 -name "*.txt"

# Limit maximum depth to 2 levels
$ find /home -maxdepth 2 -name "*.txt"

# At least depth 2
$ find /home -mindepth 2 -name "*.txt"

Execute Actions on Results

-exec execute command

bash

# Delete found files
$ find /tmp -name "*.tmp" -exec rm {} \;

# Modify permissions
$ find /var/www -type f -exec chmod 644 {} \;

# Copy files
$ find /home -name "*.txt" -exec cp {} /backup/ \;

# Show detailed information
$ find /home -name "*.txt" -exec ls -l {} \;

-exec use + for efficiency

bash

# Process multiple files at once (more efficient)
$ find /home -name "*.txt" -exec ls -l {} +

# Batch delete
$ find /tmp -name "*.tmp" -exec rm {} +

-ok interactive confirmation

bash

# Confirm before deletion
$ find /tmp -name "*.tmp" -ok rm {} \;

Use xargs

bash

# Basic usage
$ find /home -name "*.txt" | xargs ls -l

# Handle filenames with spaces
$ find /home -name "*.txt" -print0 | xargs -0 ls -l

# Limit number of files processed each time
$ find /home -name "*.txt" | xargs -n 10 ls -l

Practical Examples

bash

# Find and delete logs 7 days old
$ find /var/log -name "*.log" -mtime +7 -delete

# Find large files
$ find / -type f -size +100M 2>/dev/null

# Find recently modified configuration files
$ find /etc -name "*.conf" -mtime -1

# Find and compress old files
$ find /backup -mtime +30 -exec gzip {} \;

# Count files
$ find /home -type f | wc -l

# Find duplicate filenames
$ find /home -type f -name "*.txt" -printf "%f\n" | sort | uniq -d

locate Command

locate uses a pre-built database for fast file searching.

Installation

bash

# Debian/Ubuntu
$ sudo apt install mlocate

# Fedora
$ sudo dnf install mlocate

Basic Usage

bash

# Search for files
$ locate file.txt

# Case-insensitive
$ locate -i FILE.TXT

# Limit result count
$ locate -n 10 "*.txt"

# Show only existing files
$ locate -e file.txt

# Show match count
$ locate -c "*.txt"

Update Database

bash

# Manually update database
$ sudo updatedb

find vs locate

Feature	find	locate
Speed	Slower (real-time search)	Very fast (database query)
Real-time	Real-time	Needs database update
Features	Rich (condition filtering)	Simple (name matching)
Resource usage	Higher	Very low

which Command

Find location of executable commands.

bash

# Find command location
$ which ls
/usr/bin/ls

$ which python
/usr/bin/python

# Find all matches
$ which -a python
/usr/bin/python
/usr/local/bin/python

whereis Command

Find command's binary, source, and manual pages.

bash

$ whereis ls
ls: /usr/bin/ls /usr/share/man/man1/ls.1.gz

$ whereis python
python: /usr/bin/python /usr/lib/python3.10 /usr/share/man/man1/python.1.gz

# Find only binary
$ whereis -b ls

# Find only manual
$ whereis -m ls

type Command

Display command type and location.

bash

$ type ls
ls is aliased to `ls --color=auto'

$ type cd
cd is a shell builtin

$ type python
python is /usr/bin/python

# Show all locations
$ type -a ls

grep Search File Content

Although grep is mainly for searching file content, it can also be used for file search combined with other commands.

bash

# Search content in files
$ grep "pattern" file.txt

# Recursive search in directories
$ grep -r "pattern" /path/to/dir/

# Show only filenames
$ grep -l "pattern" *.txt

# Show line numbers
$ grep -n "pattern" file.txt

# Case-insensitive
$ grep -i "pattern" file.txt

# Reverse match (not containing)
$ grep -v "pattern" file.txt

Combine with find

bash

# Search in .txt files
$ find /home -name "*.txt" -exec grep -l "keyword" {} \;

# Use xargs
$ find /home -name "*.txt" | xargs grep "keyword"

fd - Modern find Alternative

fd is a modern alternative to find, faster and more intuitive.

Installation

bash

# Debian/Ubuntu
$ sudo apt install fd-find
# Command name is fdfind, can create alias
$ alias fd=fdfind

# Fedora
$ sudo dnf install fd-find

# Arch Linux
$ sudo pacman -S fd

Basic Usage

bash

# Simple search (recursive by default)
$ fd pattern

# Specify directory
$ fd pattern /path/to/dir

# Search specific extensions
$ fd -e txt

# Search specific type
$ fd -t f pattern    # Files
$ fd -t d pattern    # Directories

# Execute command
$ fd -e txt -x rm {}

ripgrep (rg) - Fast Content Search

ripgrep is one of the fastest content search tools.

Installation

bash

# Debian/Ubuntu
$ sudo apt install ripgrep

# Fedora
$ sudo dnf install ripgrep

# Arch Linux
$ sudo pacman -S ripgrep

Basic Usage

bash

# Recursive search (default)
$ rg "pattern"

# Search in specific directory
$ rg "pattern" /path/to/dir

# Specify file types
$ rg -t py "pattern"    # Python files
$ rg -t js "pattern"    # JavaScript files

# Show only filenames
$ rg -l "pattern"

# Show context
$ rg -C 3 "pattern"    # 3 lines before and after

# Ignore case
$ rg -i "pattern"

Practical Search Tips

Find Largest Files

bash

# Top 10 largest files
$ find / -type f -exec du -h {} + 2>/dev/null | sort -rh | head -10

# Or use du
$ du -ah /home | sort -rh | head -20

Find Recently Modified Files

bash

# Files modified in last 24 hours
$ find /home -type f -mtime -1

# Sort by modification time
$ find /home -type f -printf "%T@ %p\n" | sort -n | tail -10

Find Duplicate Files

bash

# Use fdupes
$ sudo apt install fdupes
$ fdupes -r /home

Find Broken Symbolic Links

bash

$ find /home -xtype l

Find Files in Specific Size Range

bash

# Files between 1MB and 10MB
$ find /home -type f -size +1M -size -10M

Exclude Directories

bash

# Exclude .git directory
$ find /home -name ".git" -prune -o -name "*.txt" -print

# Exclude multiple directories
$ find /home \( -name node_modules -o -name .git \) -prune -o -name "*.js" -print

Summary

This chapter introduced Linux file search tools:

find: Most powerful, supports complex condition search
locate: Fast search, uses database
which/whereis/type: Find command locations
grep: Search file content
fd: Modern alternative to find
ripgrep: Fast content search

In daily use:

Simple filename search with locate
Complex condition search with find
Content search with grep or ripgrep
Find commands with which

Mastering these tools will allow you to quickly find the files you need in a vast filesystem.

Previous chapter: File Permissions

Next chapter: Shell Introduction

File Search ​

Overview ​

find Command ​

Basic Syntax ​

Search by Name ​

Search by Type ​

Search by Size ​

Search by Time ​

Search by Permissions ​

Search by Ownership ​

Combine Conditions ​

Limit Search Depth ​

Execute Actions on Results ​

-exec execute command ​

-exec use + for efficiency ​

-ok interactive confirmation ​

Use xargs ​

Practical Examples ​

locate Command ​

Installation ​

Basic Usage ​

Update Database ​

find vs locate ​

which Command ​

whereis Command ​

type Command ​

grep Search File Content ​

Combine with find ​

fd - Modern find Alternative ​

Installation ​

Basic Usage ​

ripgrep (rg) - Fast Content Search ​

Installation ​

Basic Usage ​

Practical Search Tips ​

Find Largest Files ​

Find Recently Modified Files ​

Find Duplicate Files ​

Find Broken Symbolic Links ​

Find Files in Specific Size Range ​

Exclude Directories ​

Summary ​

File Search

Overview

find Command

Basic Syntax

Search by Name

Search by Type

Search by Size

Search by Time

Search by Permissions

Search by Ownership

Combine Conditions

Limit Search Depth

Execute Actions on Results

-exec execute command

-exec use + for efficiency

-ok interactive confirmation

Use xargs

Practical Examples

locate Command

Installation

Basic Usage

Update Database

find vs locate

which Command

whereis Command

type Command

grep Search File Content

Combine with find

fd - Modern find Alternative

Installation

Basic Usage

ripgrep (rg) - Fast Content Search

Installation

Basic Usage

Practical Search Tips

Find Largest Files

Find Recently Modified Files

Find Duplicate Files

Find Broken Symbolic Links

Find Files in Specific Size Range

Exclude Directories

Summary