Linux Commands Cheatsheet

This repository contains a comprehensive cheatsheet for Linux commands, organized by categories for easy reference. Whether you're a beginner or an experienced user, this cheatsheet will help you quickly find the commands you need for various tasks.

Table of Contents | Categories

• File System Navigation: Commands for navigating the file system, such as pwd, ls, and cd.
• File Operations: Commands for creating, copying, moving, and deleting files and directories, such as touch, mkdir, cp, mv, and rm.
• File Content: Commands for viewing and searching file content, such as cat, less, head, tail, grep, wc, and diff.
• File Permissions: Commands for managing file permissions and ownership, such as chmod and chown.
• Process Management: Commands for managing processes, such as ps, top, kill, bg, fg, and nohup.
• System Information: Commands for retrieving system information, such as uname, hostname, df, du, free, and uptime.
• Package Management: Commands for managing packages on Debian/Ubuntu, Red Hat/Fedora, and Arch Linux systems.
• Network Commands: Commands for network configuration and troubleshooting, such as ping, ifconfig, netstat, wget, curl, ssh, and scp.
• Text Processing: Commands for processing text files, such as echo, cut, sort, uniq, tr, sed, and awk.
• Compression and Archiving: Commands for compressing and archiving files, such as tar, gzip, gunzip, zip, and unzip.
• User Management: Commands for managing user accounts, such as useradd, usermod, userdel, passwd, sudo, and su.
• Special Operators: Operators for redirecting output, running commands in the background, and combining commands.
• System Control: Commands for controlling the system, such as shutdown, reboot, systemctl, journalctl, crontab, at, mount, and umount.
• Shell Scripting Basics: Basic syntax and commands for writing shell scripts, such as #!/bin/bash, if, for, while, $variable, $(), and $(( )).

File System Navigation

Command	Description	Example
pwd	Print working directory	pwd → /home/user
ls	List directory contents	ls → Lists files in current directory
ls -l	List in long format	ls -l → Shows detailed file information
ls -a	List all files (including hidden)	ls -a → Shows hidden files starting with dot
ls -lh	List with human-readable sizes	ls -lh → Shows sizes as KB, MB, etc.
cd	Change directory	cd Documents → Move to Documents folder
cd ..	Move up one directory	cd .. → Move to parent directory
cd ~	Change to home directory	cd ~ → Go to your home directory
cd /	Change to root directory	cd / → Go to system root
find	Find files/directories	find . -name "file.txt" → Find file.txt in current directory

File Operations

Command	Description	Example
touch	Create empty file	touch newfile.txt → Creates empty newfile.txt
mkdir	Create directory	mkdir new_folder → Creates new_folder directory
mkdir -p	Create nested directories	mkdir -p dir1/dir2/dir3 → Creates directory tree
cp	Copy files/directories	cp file.txt backup/ → Copy file.txt to backup directory
cp -r	Copy directories recursively	cp -r folder backup/ → Copy folder and contents to backup
mv	Move/rename files	mv file.txt newname.txt → Rename file.txt to newname.txt
mv	Move files to directory	mv file.txt Documents/ → Move file.txt to Documents folder
rm	Remove files	rm file.txt → Delete file.txt
rm -r	Remove directories recursively	rm -r folder → Delete folder and its contents
rm -f	Force remove files	rm -f file.txt → Delete file without confirmation
rmdir	Remove empty directories	rmdir empty_folder → Delete empty_folder if empty

File Content

Command	Description	Example
cat	Display file content	cat file.txt → Shows content of file.txt
less	View file with pagination	less large_file.txt → Browse through large_file.txt
head	Show first part of file	head -n 10 file.txt → Display first 10 lines
tail	Show last part of file	tail -n 20 file.txt → Display last 20 lines
tail -f	Monitor file changes	tail -f /var/log/syslog → Show and follow log updates
grep	Search text in files	grep "search term" file.txt → Find "search term" in file.txt
grep -r	Recursive search	grep -r "term" /home/user → Search in all files under directory
wc	Count lines, words, chars	wc -l file.txt → Count lines in file.txt
diff	Compare files	diff file1.txt file2.txt → Show differences between files

File Permissions

Command	Description	Example
chmod	Change file permissions	chmod 755 script.sh → Set rwx-rx-rx permissions
chmod +x	Make file executable	chmod +x script.sh → Add execute permission
chmod -R	Change permissions recursively	chmod -R 755 directory/ → Set permissions for all files in directory
chown	Change file owner	chown user:group file.txt → Change owner and group
chown -R	Change owner recursively	chown -R user directory/ → Change owner for directory and contents

Process Management

Command	Description	Example
ps	Show running processes	ps → List your processes
ps aux	Show all processes	ps aux → List all processes with details
top	Interactive process viewer	top → Show real-time process activity
htop	Enhanced process viewer	htop → Interactive process viewer (may need installation)
kill	Terminate process	kill 1234 → Terminate process with PID 1234
kill -9	Force terminate process	kill -9 1234 → Forcefully kill process
killall	Kill processes by name	killall firefox → Kill all Firefox processes
bg	Send process to background	bg → Resume suspended job in background
fg	Bring process to foreground	fg → Bring last background job to foreground
jobs	List background jobs	jobs → Show background processes
nohup	Run command immune to hangups	nohup command & → Run in background, persist after logout

System Information

Command	Description	Example
uname	Show system information	uname -a → Display all system info
uname -r	Show kernel version	uname -r → Display kernel release
lsb_release	Show distribution info	lsb_release -a → Display Linux distribution details
hostname	Show system hostname	hostname → Display computer name
whoami	Show current username	whoami → Display your username
id	Show user identity	id → Display user and group IDs
df	Show disk usage	df -h → Show disk space in human-readable format
du	Show directory space usage	du -h directory/ → Show directory size
free	Show memory usage	free -h → Display RAM usage in human-readable format
uptime	Show system uptime	uptime → Show how long system has been running

Package Management

Debian/Ubuntu (APT)

Command	Description	Example
apt update	Update package lists	sudo apt update → Refresh available package info
apt upgrade	Upgrade packages	sudo apt upgrade → Upgrade all installed packages
apt install	Install packages	sudo apt install package_name → Install new package
apt remove	Remove packages	sudo apt remove package_name → Uninstall package
apt search	Search packages	apt search keyword → Find packages matching keyword
apt list	List packages	apt list --installed → Show installed packages
dpkg -i	Install .deb file	sudo dpkg -i package.deb → Install from downloaded .deb file

Red Hat/Fedora (DNF/YUM)

Command	Description	Example
dnf check-update	Check for updates	sudo dnf check-update → Check for package updates
dnf upgrade	Upgrade packages	sudo dnf upgrade → Upgrade all packages
dnf install	Install packages	sudo dnf install package_name → Install new package
dnf remove	Remove packages	sudo dnf remove package_name → Uninstall package
dnf search	Search packages	dnf search keyword → Find packages matching keyword
dnf list	List packages	dnf list installed → Show installed packages
rpm -i	Install .rpm file	sudo rpm -i package.rpm → Install from downloaded .rpm file

Arch Linux (Pacman)

Command	Description	Example
pacman -Sy	Sync package database	sudo pacman -Sy → Update package database
pacman -Syu	Update system	sudo pacman -Syu → Update package database and upgrade
pacman -S	Install packages	sudo pacman -S package_name → Install new package
pacman -R	Remove packages	sudo pacman -R package_name → Uninstall package
pacman -Ss	Search packages	pacman -Ss keyword → Find packages matching keyword
pacman -Q	List packages	pacman -Q → Show installed packages

Network Commands

Command	Description	Example
ping	Test connectivity	ping google.com → Check connection to google.com
ifconfig	Show network interfaces	ifconfig → Display network interface configuration
ip addr	Modern interface config	ip addr → Show IP addresses and network interfaces
netstat	Network statistics	netstat -tuln → Show active network connections
ss	Socket statistics	ss -tuln → Modern replacement for netstat
wget	Download files	wget https://example.com/file.zip → Download file
curl	Transfer data	curl https://example.com → Fetch web page content
ssh	Secure shell	ssh user@hostname → Connect to remote server
scp	Secure copy	scp file.txt user@hostname:/path/ → Copy file to remote server
rsync	Remote sync	rsync -avz folder/ user@host:/path/ → Sync directory to remote host
dig	DNS lookup	dig example.com → Query DNS for domain
nslookup	Name server lookup	nslookup example.com → Query DNS for domain
traceroute	Trace network path	traceroute google.com → Show path packets take to server

Text Processing

Command	Description	Example
echo	Print text	echo "Hello World" → Display text
cut	Extract sections from lines	cut -d "," -f 1 file.csv → Extract first column from CSV
sort	Sort lines	sort file.txt → Sort file content alphabetically
uniq	Remove duplicates	sort file.txt | uniq → Show unique sorted lines
tr	Translate characters	cat file.txt | tr '[a-z]' '[A-Z]' → Convert to uppercase
sed	Stream editor	sed 's/old/new/g' file.txt → Replace "old" with "new"
awk	Pattern scanning	awk '{print $1}' file.txt → Print first column

Compression and Archiving

Command	Description	Example
tar	Archive files	tar -cf archive.tar files/ → Create tar archive
tar -x	Extract archive	tar -xf archive.tar → Extract tar archive
tar -z	Compress with gzip	tar -czf archive.tar.gz files/ → Create compressed archive
gzip	Compress files	gzip file.txt → Compress to file.txt.gz
gunzip	Decompress gzip	gunzip file.txt.gz → Decompress gzip file
zip	Create zip archive	zip -r archive.zip directory/ → Compress directory to zip
unzip	Extract zip archive	unzip archive.zip → Extract zip archive

User Management

Command	Description	Example
useradd	Create user	sudo useradd newuser → Create new user account
usermod	Modify user	sudo usermod -aG group user → Add user to a group
userdel	Delete user	sudo userdel username → Delete user account
passwd	Change password	passwd → Change your password
sudo	Execute as superuser	sudo command → Run command with superuser privileges
su	Switch user	su username → Switch to another user account
groups	Show user groups	groups username → Show groups a user belongs to

Special Operators

Operator	Description	Example
>	Redirect output	command > file.txt → Save output to file.txt
>>	Append output	command >> file.txt → Append output to file.txt
<	Input redirection	command < file.txt → Use file.txt as input
|	Pipe output	command1 | command2 → Use output of command1 as input to command2
&	Run in background	command & → Run command in the background
&&	Logical AND	command1 && command2 → Run command2 if command1 succeeds
||	Logical OR	command1 || command2 → Run command2 if command1 fails
;	Command separator	command1 ; command2 → Run command2 after command1

System Control

Command	Description	Example
shutdown	Shutdown system	sudo shutdown -h now → Shutdown immediately
reboot	Restart system	sudo reboot → Restart immediately
systemctl	Control systemd services	sudo systemctl start service → Start a service
systemctl status	Check service status	systemctl status service → Show service status
journalctl	View logs	journalctl -u service → View logs for a service
crontab	Schedule tasks	crontab -e → Edit cron jobs
at	Schedule one-time tasks	at now + 1 hour → Schedule task in 1 hour
mount	Mount filesystems	sudo mount /dev/sdb1 /mnt → Mount device to directory
umount	Unmount filesystems	sudo umount /mnt → Unmount directory

Shell Scripting Basics

Command/Syntax	Description	Example
#!/bin/bash	Shebang line	First line of script to specify interpreter
if [ condition ]	Conditional statement	if [ "$a" -eq "$b" ]; then echo "Equal"; fi
for loop	Loop through items	for i in {1..5}; do echo $i; done
while loop	Loop while condition is true	while [ $i -lt 10 ]; do echo $i; i=$((i+1)); done
$variable	Variable reference	echo $HOME → Display HOME variable value
$()	Command substitution	echo "Date: $(date)" → Include command output in string
$(())	Arithmetic expansion	echo $((5+3)) → Perform arithmetic

Contributing

Contributions are welcome! If you have any suggestions, improvements, or additional commands that you think should be included in this cheatsheet, please feel free to submit a pull request or open an issue on GitHub.

To contribute:

1. Fork the repository.
2. Create a new branch (git checkout -b feature-branch).
3. Make your changes.
4. Commit your changes (git commit -m 'Add some feature').
5. Push to the branch (git push origin feature-branch).
6. Open a pull request.

License

This project is licensed under the MIT License. See the LICENSE file for more details.

Acknowledgments

• Linux Documentation Project
• Linux Command
• SS64
• TLDP Advanced Bash-Scripting Guide

Thank you to all the contributors and the open-source community for their valuable resources and support.