Linux Command Cheat Sheet

A comprehensive reference for essential Linux commands organized by function. Master file operations, process management, networking, system administration, and more.

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1. Navigation & File System

Command	Description
pwd	Print working directory
ls	List directory contents
ls -la	List with hidden files and full details
ls -lh	List with human-readable file sizes
ls -lt	List sorted by modification time
cd	Change directory
cd ~	Change to home directory
cd -	Change to previous directory
cd /	Change to root directory
mkdir	Create a directory
mkdir -p	Create directories recursively
rmdir	Remove empty directory
cp	Copy file or directory
cp -r	Copy directory recursively
cp -v	Copy with verbose output
mv	Move or rename file/directory
rm	Remove file
rm -r	Remove directory recursively
rm -f	Force remove without confirmation
touch	Create empty file or update timestamp
find	Search for files by name, type, size, etc.
find . -name "*.txt"	Find all .txt files in current directory
find / -size +100M	Find files larger than 100MB
locate	Find files by name (fast, uses database)
updatedb	Update locate database
tree	Display directory structure as tree
tree -L 2	Show tree with depth limit 2
ln	Create hard link
ln -s	Create symbolic link
readlink	Display target of symbolic link
stat	Display file/directory statistics
file	Determine file type
basename	Get filename from path
dirname	Get directory path from full path

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2. File Viewing & Editing

Command	Description
cat	Display file contents
cat file1 file2	Concatenate multiple files
head	Show first 10 lines
head -n 20	Show first 20 lines
tail	Show last 10 lines
tail -f	Follow file (watch updates)
less	View file with pagination
more	View file with pagination (less advanced)
nano	Simple text editor
vi or vim	Advanced text editor
vim -u NONE	Open vim without configuration
tee	Read from stdin and write to file and stdout
wc	Count words, lines, characters
wc -l	Count lines only
nl	Display file with line numbers
od	Dump file in octal/hex format
hexdump	Display file in hexadecimal
xxd	Create hex dumps or convert hex to binary

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3. Text Processing

Command	Description
grep	Search for pattern in files
grep -i	Case-insensitive search
grep -r	Search recursively in directories
grep -v	Invert match (show non-matching lines)
grep -n	Show line numbers
grep -E	Use extended regex
egrep	Extended grep (equivalent to grep -E)
fgrep	Fixed string search (no regex)
sed	Stream editor for filtering/transforming text
sed 's/old/new/'	Replace first occurrence on each line
sed 's/old/new/g'	Replace all occurrences
sed -n '5,10p'	Print lines 5-10
sed '10d'	Delete line 10
awk	Text processing and pattern scanning
awk '{print $1}'	Print first column
awk -F:	Set field separator
sort	Sort lines
sort -n	Numeric sort
sort -r	Reverse sort
sort -u	Sort and remove duplicates
uniq	Remove duplicate consecutive lines
uniq -c	Count duplicate lines
cut	Extract columns from text
cut -d: -f1	Extract field 1 with : separator
tr	Translate or delete characters
tr 'a-z' 'A-Z'	Convert lowercase to uppercase
paste	Merge lines from files
join	Join lines based on common field
diff	Show differences between files
diff -u	Unified diff format
comm	Compare sorted files line by line
xargs	Build and execute command from input
fmt	Format text paragraphs
column	Format text into columns
column -t	Align text as table

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4. Permissions & Ownership

Command	Description
chmod	Change file/directory permissions
chmod 755	rwxr-xr-x
chmod 644	rw-r--r--
chmod u+x	Add execute for owner
chmod g-r	Remove read from group
chmod a+r	Add read for all
chown	Change file owner
chown user:group	Change owner and group
chown -R	Change ownership recursively
chgrp	Change group ownership
umask	Set default permissions for new files
getfacl	Display ACL permissions
setfacl	Set ACL permissions
chattr	Change file attributes (immutable, etc.)
chattr +i	Make file immutable
chattr -i	Remove immutable attribute
lsattr	List file attributes

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5. User & Group Management

Command	Description
useradd	Create new user
useradd -m	Create user with home directory
useradd -s /bin/bash	Specify login shell
userdel	Delete user
userdel -r	Delete user and home directory
usermod	Modify user account
usermod -aG group user	Add user to group
usermod -d /home/newdir	Change home directory
usermod -s /bin/zsh	Change login shell
groupadd	Create new group
groupdel	Delete group
groupmod	Modify group
passwd	Change user password
passwd -l	Lock user account
passwd -u	Unlock user account
whoami	Display current user
id	Display user/group IDs
id username	Show info for specific user
who	List logged-in users
w	Show logged-in users and what they're doing
last	Show login history
lastlog	Show recent login information
su	Switch user
su -	Switch user with login shell
sudo	Execute as superuser
sudo -i	Open root shell
sudo -u user	Execute as specific user
visudo	Edit sudoers file safely
finger	Display user information
finger username	Get info about specific user

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6. Process Management

Command	Description
ps	Display processes
ps aux	Show all processes with details
ps aux | grep name	Find process by name
ps -ef	Full format process listing
ps -eo pid,user,cpu,mem,comm	Custom output format
top	Interactive process monitor
top -u user	Monitor processes for specific user
htop	Enhanced process monitor
atop	Advanced system monitor
kill	Terminate process by PID
kill -9	Force kill process
kill -TERM	Graceful termination
killall	Terminate processes by name
killall -9	Force kill all processes by name
pkill	Kill processes matching pattern
pkill -f command	Kill by full command match
nice	Start process with priority
nice -n 10 command	Lower priority (higher is less important)
renice	Change process priority
renice -n 5 -p PID	Adjust priority of running process
bg	Resume suspended job in background
fg	Bring background job to foreground
jobs	List background/suspended jobs
nohup	Run command immune to hangups
nohup command &	Run in background and log to nohup.out
screen	Terminal multiplexer/session manager
tmux	Terminal multiplexer (modern alternative)
pgrep	Find processes by name/pattern
pgrep -l	Show process name and PID

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7. Networking

Command	Description
ip addr	Show IP addresses
ip addr show	Display all interfaces
ip addr add IP/MASK dev eth0	Add IP address
ip link	Show link layer information
ip link set eth0 up	Bring interface up
ip link set eth0 down	Bring interface down
ifconfig	Legacy network interface config (deprecated)
ifconfig eth0	Show specific interface
ss	Socket statistics (modern netstat replacement)
ss -tlnp	Show listening TCP ports with processes
ss -ulnp	Show listening UDP ports with processes
netstat	Network statistics (legacy)
netstat -tlnp	Show listening ports
netstat -an	Show all connections
ping	Test connectivity to host
ping -c 4	Send 4 pings
traceroute	Trace route to host
tracepath	Trace path (doesn't need root)
mtr	Network diagnostic tool (ping + traceroute)
dig	DNS query tool
dig example.com	Query A record
dig +short	Short answer only
dig @8.8.8.8	Query specific nameserver
nslookup	Query DNS (simpler than dig)
host	Simple DNS lookup
curl	Transfer data with URLs
curl -I	Fetch headers only
curl -X POST -d data	Make POST request
wget	Download files from web
wget -O filename	Save with specific name
wget -r	Download recursively
scp	Secure copy between hosts
scp file user@host:/path/	Copy file to remote
rsync	Synchronize files between systems
rsync -avz	Verbose, archive, compressed
ssh	Secure shell connection
ssh -i key.pem user@host	Connect with specific key
ssh -L 8000:localhost:3000	Local port forwarding
ssh -R 8000:localhost:3000	Remote port forwarding
ssh -D 1080	Dynamic proxy (SOCKS)
nc	Netcat - network utility
nc -l -p 5000	Listen on port 5000
nc -zv host port	Check if port is open
tcpdump	Packet sniffer
tcpdump -i eth0	Capture on specific interface
tcpdump -n	Don't resolve DNS
nmap	Network scanner
nmap -sn 192.168.1.0/24	Scan network for hosts
nmap -p 80,443	Scan specific ports
telnet	Telnet client (insecure)
hostname	Display system hostname
hostname -I	Show all IP addresses
hostnamectl	Manage system hostname
route	Show routing table
route -n	Numeric (no DNS resolution)
arp	Address resolution protocol table
arp -a	Show ARP cache

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8. Disk & Storage

Command	Description
df	Disk free space
df -h	Human-readable format
df -T	Show filesystem type
du	Disk usage of directories
du -sh	Summary in human-readable format
du -sh *	Size of each item in directory
du -sh * | sort -h	Show sizes sorted
lsblk	List block devices
blkid	Show block device IDs/UUIDs
fdisk	Partition table manipulator
fdisk -l	List partitions
parted	GNU Parted partition editor
mount	Mount filesystem
mount /dev/sda1 /mnt/	Mount device to mountpoint
umount	Unmount filesystem
umount /mnt/	Unmount directory
mkfs	Create filesystem
mkfs.ext4	Create ext4 filesystem
mkfs.vfat	Create FAT filesystem
fsck	Filesystem check and repair
e2fsck	Check ext filesystem
fstab	Static filesystem mount table (/etc/fstab)
dd	Copy and convert data
dd if=/dev/zero of=file bs=1M count=100	Create 100MB file
dd if=/dev/sda of=backup.img	Disk backup

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9. Archive & Compression

Command	Description
tar	Archive files
tar -cvf archive.tar files/	Create archive
tar -xvf archive.tar	Extract archive
tar -tf archive.tar	List contents
tar -czf archive.tar.gz files/	Create gzip compressed
tar -xzf archive.tar.gz	Extract gzip
tar -cjf archive.tar.bz2 files/	Create bzip2 compressed
tar -xjf archive.tar.bz2	Extract bzip2
gzip	Compress file
gzip file	Creates file.gz
gunzip	Decompress gzip
bzip2	Compress with bzip2
bunzip2	Decompress bzip2
xz	Compress with xz
unxz	Decompress xz
zip	ZIP archive
zip -r archive.zip folder/	Zip directory recursively
unzip	Extract ZIP
unzip -l	List ZIP contents
7z	7-Zip archive tool
zcat	View compressed file contents
zgrep	Grep in compressed file

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10. System Information

Command	Description
uname	System information
uname -a	All system information
uname -r	Kernel release/version
uname -m	Machine hardware name (x86_64)
lsb_release -a	Linux distribution version
cat /etc/os-release	OS information
hostname	System hostname
uptime	System uptime and load
date	Current date and time
cal	Calendar
free	Memory usage
free -h	Human-readable format
free -m	Memory in megabytes
lscpu	CPU information
lspci	PCI devices (graphics cards, etc.)
lsusb	USB devices
dmesg	Kernel messages
dmesg | tail	Latest kernel messages
journalctl	System journal logs
journalctl -xe	Recent errors
timedatectl	Time and date settings
timedatectl set-timezone	Set timezone
hwinfo	Detailed hardware information
inxi	System information summary

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11. Service Management

Command	Description
systemctl	Control systemd services
systemctl status service	Check service status
systemctl start service	Start service
systemctl stop service	Stop service
systemctl restart service	Restart service
systemctl reload service	Reload configuration
systemctl enable service	Enable service at boot
systemctl disable service	Disable service at boot
systemctl list-units	List all units
systemctl list-units --failed	Show failed units
journalctl -u service	View service logs
journalctl -u service -f	Follow service logs

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12. Package Management

Command	Description
apt	Debian/Ubuntu package manager
apt update	Update package lists
apt upgrade	Upgrade packages
apt install package	Install package
apt remove package	Remove package
apt search package	Search for package
apt list --upgradable	Show upgradable packages
yum	RedHat/CentOS package manager
yum install package	Install on RHEL/CentOS
yum update	Update packages
dnf	Modern Fedora package manager
dnf install package	Install on Fedora
pacman	Arch Linux package manager
pacman -S package	Install on Arch
apk	Alpine Linux package manager
apk add package	Install on Alpine
rpm	Red Hat Package Manager
rpm -i package.rpm	Install RPM
rpm -qa	Query all installed packages
dpkg	Debian package manager
dpkg -l	List installed packages
dpkg -i package.deb	Install DEB
snap	Universal package manager
snap install app	Install snap application

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13. Shell Scripting Essentials

Command	Description
echo	Print text
echo -n	Print without newline
echo -e	Enable escape sequences
echo $VAR	Print variable value
read	Read user input
read -p "prompt" var	Prompt and read into variable
test	Evaluate condition (same as [)
[ -f file ]	Test if file exists
[ -d dir ]	Test if directory exists
[ -z string ]	Test if string is empty
[ $a -eq $b ]	Numeric equality
[ $a -lt $b ]	Less than
[[ $str =~ pattern ]]	Regex match
if then fi	Conditional statement
if then else fi	If-else statement
if then elif then fi	If-elif-else
for var in list; do done	For loop
for ((i=0; i less than 10; i++)); do done	C-style for loop
while condition; do done	While loop
case $var in pattern) ;; esac	Switch statement
function name() { }	Define function
$0, $1, $2	Script name and arguments
$#	Number of arguments
$@	All arguments as array
$?	Exit code of last command
exit 0	Exit with code 0 (success)
trap 'cleanup' EXIT	Run command on exit/signal

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14. Useful One-Liners

File Operations

# Find largest files in current directory
find . -type f -exec ls -lh {} \; | sort -k5 -rh | head -10

# Find files modified in last 7 days
find . -type f -mtime -7

# Find duplicate files
find . -type f -exec md5sum {} \; | sort | uniq -d

# Count all lines in all files in directory
find . -type f -name "*.txt" -exec wc -l {} + | tail -1

# Recursively search for string in files
grep -r "search_term" /path/to/search

# Replace string in all files in directory
find . -type f -name "*.txt" -exec sed -i 's/old/new/g' {} \;

Monitoring & Processes

# Monitor log file in real-time
tail -f /var/log/syslog

# Find which process is using a specific port
lsof -i :8080

# Check all open ports and processes
netstat -tulnp | grep LISTEN

# Show CPU and memory usage by process
ps aux --sort=-%cpu | head -10
ps aux --sort=-%mem | head -10

# Monitor directory for changes
watch -n 2 'ls -lah /path/to/dir'

Network

# Check if port is open
nc -zv hostname port

# Quick DNS lookup
dig +short example.com

# Find all hosts on network
nmap -sn 192.168.1.0/24

# Show current network connections
ss -tan | grep ESTABLISHED

System Administration

# Show disk usage by directory (top 10)
du -sh */ | sort -rh | head -10

# List files by size in current directory
ls -lhS

# Count files in directory
find . -type f | wc -l

# Show system load average
uptime

# Display top resource consumers
top -b -n 1 | head -20

Text Processing

# Extract column from CSV
awk -F',' '{print $1, $3}' file.csv

# Sort and count occurrences
sort | uniq -c | sort -rn

# Remove duplicates while preserving order
awk '!seen[$0]++' file.txt

# Print specific lines
sed -n '10,20p' file.txt

# Split large file into parts
split -l 1000 largefile.txt part_

# Merge sorted files
sort -m file1.txt file2.txt file3.txt

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Quick Reference by Task

Need to find something?

• find - Comprehensive file search
• locate - Quick file search (uses database)
• grep - Search within files

Need to view/edit files?

• cat - Quick view
• less - Scroll through large files
• nano - Simple editor
• vim - Powerful editor

Need to manage processes?

• ps - List processes
• top / htop - Interactive monitor
• kill - Terminate process
• bg / fg - Background/foreground

Need to check system?

• df - Disk space
• free - Memory usage
• top - CPU/memory
• systemctl - Service status

Need to manage users?

• useradd / userdel - Create/delete users
• passwd - Change passwords
• chmod / chown - Permissions/ownership

Need to work with archives?

• tar - Most common
• zip / unzip - ZIP format
• gzip / gunzip - Gzip compression