Searching Files and Directories¶

Linux provides powerful tools to search for files, directories, commands, and executables. Whether you're locating configuration files, troubleshooting applications, or managing production servers, mastering file search commands is an essential Linux skill.

Learning Path¶

Linux Mastery → Module 2: Linux Command Line Essentials → Lesson 6

Difficulty: Beginner

Reading Time: 30 Minutes

Course Progress

Course: Linux Mastery

Module: Linux Command Line Essentials

Lesson: 6 of 10

What You'll Learn¶

After completing this lesson, you'll be able to:

Search files and directories
Search by name
Search by type
Search by size
Search by owner
Search by permissions
Search by modification time
Locate executables
Search efficiently in production systems

Prerequisites¶

Before starting this lesson, complete:

Module 1 – Linux Fundamentals
Module 2 Lessons 1–5

Why Learn File Searching?¶

Imagine you're working on a production server.

You need to find:

NGINX configuration
Docker Compose file
Kubernetes manifests
SSH configuration
Log files
Recently modified files

Instead of manually browsing thousands of directories, Linux provides commands that can find them in seconds.

Linux Search Commands¶

Linux offers several search utilities.

Command	Purpose
find	Search files and directories
locate	Fast filename search
which	Find executable in PATH
whereis	Locate binary, source and man pages
type	Identify command type

Each command solves a different problem.

The find Command¶

find is the most powerful file search command.

Syntax

find <path> <expression>

Search from current directory:

find .

Search entire filesystem:

find /

Search by File Name¶

Find a file named:

find . -name "notes.txt"

Example output:

./Documents/notes.txt

Case-Insensitive Search¶

find . -iname "notes.txt"

Matches:

Notes.txt

NOTES.TXT

notes.txt

Search Directories¶

find . -type d

Output:

.

./projects

./logs

./backup

Search Regular Files¶

find . -type f

Search Hidden Files¶

find . -name ".*"

Search Using Wildcards¶

Find all text files.

find . -name "*.txt"

Find all YAML files.

find . -name "*.yaml"

Find shell scripts.

find . -name "*.sh"

Search by Size¶

Files larger than 100 MB

find . -size +100M

Files smaller than 10 KB

find . -size -10k

Exactly 50 MB

find . -size 50M

Search by Owner¶

find /home -user basha

Search by Group¶

find /home -group developers

Search by Permissions¶

Example:

find . -perm 644

Find executable files.

find . -perm /111

Search by Modification Time¶

Modified today

find . -mtime 0

Modified within last 7 days

find . -mtime -7

Older than 30 days

find . -mtime +30

Search Empty Files¶

find . -empty

Execute Commands on Search Results¶

Delete log files.

find . -name "*.log" -delete

Display file details.

find . -name "*.txt" -exec ls -l {} \;

Warning

Always verify search results before using -delete.

The locate Command¶

locate searches a pre-built database.

Example:

locate sshd_config

Much faster than find.

Update locate Database¶

Ubuntu

sudo updatedb

Now:

locate nginx.conf

which¶

Find executable location.

which python3

Example

/usr/bin/python3

Useful for verifying installed commands.

whereis¶

Displays:

Binary
Source
Manual page

Example:

whereis ssh

Output

ssh:
/usr/bin/ssh
/usr/share/man/man1/ssh.1.gz

type¶

Identify command type.

type ls

Output

ls is /usr/bin/ls

Example

type cd

Output

cd is a shell builtin

Command Comparison¶

Command	Best For
find	Powerful searches
locate	Fast filename search
which	Executables
whereis	Binary + Man Page
type	Built-in vs External

Real Production Examples¶

Find NGINX configuration.

find /etc -name nginx.conf

Find Docker Compose files.

find /opt -name docker-compose.yml

Find Kubernetes YAML.

find . -name "*.yaml"

Find large log files.

find /var/log -size +500M

Find recently modified files.

find /etc -mtime -1

Find executable shell scripts.

find . -name "*.sh" -perm /111

Production Perspective¶

System administrators frequently search for:

Configuration files
Log files
Core dumps
Backup archives
SSL certificates
Shell scripts
Kubernetes manifests
Docker files

Knowing how to search efficiently can significantly reduce troubleshooting time.

Hands-on Lab¶

Task 1¶

Create a lab.

mkdir search-lab

cd search-lab

Task 2¶

Create files.

touch app.py

touch config.yaml

touch nginx.conf

touch notes.txt

touch script.sh

Task 3¶

Search YAML.

find . -name "*.yaml"

Task 4¶

Search shell scripts.

find . -name "*.sh"

Task 5¶

Search files only.

find . -type f

Task 6¶

Search directories.

find . -type d

Task 7¶

Locate Python.

which python3

Task 8¶

Find SSH.

whereis ssh

Task 9¶

Identify command type.

type cd

type ls

Command Deep Dive¶

Command	Purpose	Common Options	Production Example
find	Search filesystem	`-name`, `-type`, `-size`, `-mtime`	Find configs and logs
locate	Fast filename search	`-i`	Locate SSH configs
which	Find executable	Default	Verify installed tools
whereis	Binary + docs	Default	Find binaries
type	Command type	`-a`	Check shell built-ins

Production Troubleshooting Scenario¶

Scenario

A web application has stopped working after a configuration change.

Your tasks:

Find the NGINX configuration file.
Locate all backup configuration files.
Identify recently modified configuration files.
Find log files larger than 100 MB.
Verify where the nginx executable is installed.

Example commands:

find /etc -name "nginx.conf"

find /etc -name "*.bak"

find /etc -mtime -1

find /var/log -size +100M

which nginx

Mini Challenge¶

Create the following structure.

project/

├── app.py

├── config/

│   ├── app.yaml

│   ├── db.yaml

│   └── nginx.conf

├── logs/

│   ├── access.log

│   └── error.log

└── scripts/

    ├── deploy.sh

    └── backup.sh

Complete these tasks:

Find all .yaml files.
Find all shell scripts.
Find all log files.
Display only directories.
Find all files modified today.
Locate the bash executable.

Best Practices¶

Use find for comprehensive searches.
Use locate when speed is important.
Limit searches to specific directories instead of searching the entire filesystem.
Verify results before deleting files.
Combine search criteria for more precise results.

Common Mistakes¶

❌ Searching the entire filesystem unnecessarily.

✅ Use:

find /

This can be slow.

Instead:

find /etc

❌ Using rm immediately after find.

✅ Always inspect results first.

❌ Forgetting quotes around wildcards.

✅ Correct:

find . -name "*.log"

Interview Questions¶

Beginner¶

What is the difference between find and locate?
Which command finds executables?
How do you search for directories only?
Which command identifies built-in commands?

Intermediate¶

Explain find -exec.
How do you search files modified within the last seven days?
How do you search by permissions?
Why is locate faster than find?

Architect Level¶

How would you locate configuration files during a production outage?
How would you identify large log files consuming disk space?
How can efficient file searching reduce Mean Time to Resolution (MTTR)?

Summary¶

In this lesson, you learned:

Searching files and directories
Searching by name, type, size, owner, permissions, and modification time
Using find, locate, which, whereis, and type
Real-world search techniques used in production environments

Mastering these commands will make troubleshooting, automation, and system administration significantly faster and more efficient.

Key Takeaways¶

find is the most powerful Linux search command.
locate provides fast filename searches using an indexed database.
which finds executables in your PATH.
whereis locates binaries, source files, and manual pages.
type identifies whether a command is built-in or external.
Always verify search results before performing destructive actions.

What's Next?¶

Wildcards and Globbing

In the next lesson, you'll learn:

What wildcards are
Globbing patterns
*, ?, and []
Character ranges
Brace expansion
Real-world file selection techniques
Using wildcards safely in production