Essential Linux Commands Cheatsheet

File Management Commands

ls - List Directory Contents

# Basic listing
ls

# Detailed listing with permissions, owner, size
ls -l

# Show hidden files (starting with .)
ls -a

# Human-readable file sizes
ls -lh

# Sort by modification time (newest first)
ls -lt

# Recursive listing
ls -R

# Common combination
ls -lah

Output explained (ls -l):

-rw-r--r-- 1 user group 1234 Jan 28 10:30 file.txt
│││││││││ │ │    │     │    │           └─ filename
│││││││││ │ │    │     │    └─ modification date/time
│││││││││ │ │    │     └─ file size (bytes)
│││││││││ │ │    └─ group owner
│││││││││ │ └─ user owner
│││││││││ └─ number of hard links
└─────────── permissions

cp - Copy Files and Directories

# Copy file
cp source.txt destination.txt

# Copy to directory
cp file.txt /path/to/directory/

# Copy directory recursively
cp -r source_dir/ destination_dir/

# Copy with verbose output
cp -v file.txt /backup/

# Preserve permissions, timestamps
cp -p file.txt /backup/

# Interactive (ask before overwrite)
cp -i file.txt existing_file.txt

# Copy multiple files to directory
cp file1.txt file2.txt file3.txt /destination/

mv - Move/Rename Files

# Rename file
mv oldname.txt newname.txt

# Move file to directory
mv file.txt /path/to/directory/

# Move multiple files
mv file1.txt file2.txt /destination/

# Move directory
mv old_dir/ new_location/

# Interactive mode (ask before overwrite)
mv -i source.txt destination.txt

rm - Remove Files and Directories

# Remove file
rm file.txt

# Remove multiple files
rm file1.txt file2.txt file3.txt

# Remove directory and contents (recursive)
rm -r directory/

# Force remove (no confirmation)
rm -f file.txt

# Interactive (ask for each file)
rm -i file.txt

# Remove directory recursively with verbose output
rm -rv old_directory/

# DANGEROUS: Never run this without absolute certainty
# rm -rf /  # Destroys entire system!

mkdir - Create Directories

# Create directory
mkdir new_directory

# Create multiple directories
mkdir dir1 dir2 dir3

# Create nested directories (parents)
mkdir -p parent/child/grandchild

# Create with specific permissions
mkdir -m 755 public_directory

touch - Create Empty Files / Update Timestamps

# Create empty file
touch newfile.txt

# Create multiple files
touch file1.txt file2.txt file3.txt

# Update modification time of existing file
touch existing_file.txt

Navigation Commands

cd - Change Directory

# Go to home directory
cd
cd ~

# Go to specific directory
cd /path/to/directory

# Go up one level
cd ..

# Go up two levels
cd ../..

# Go to previous directory
cd -

# Go to root directory
cd /

pwd - Print Working Directory

# Show current directory
pwd

# Example output: /home/username/Documents

find - Search for Files

# Find file by name
find /path/to/search -name "filename.txt"

# Case-insensitive search
find /path -iname "*.jpg"

# Find directories only
find /path -type d -name "folder*"

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

# Find files larger than 100MB
find /path -type f -size +100M

# Find and delete
find /path -name "*.tmp" -delete

# Find with permissions
find /path -type f -perm 644

Text Processing Commands

cat - Display File Contents

# Display file
cat file.txt

# Display multiple files
cat file1.txt file2.txt

# Number all lines
cat -n file.txt

# Concatenate files into new file
cat file1.txt file2.txt > combined.txt

# Append to file
cat file1.txt >> existing.txt

grep - Search Text Patterns

# Search for pattern in file
grep "search_term" file.txt

# Case-insensitive search
grep -i "search_term" file.txt

# Search recursively in directory
grep -r "search_term" /path/to/dir/

# Show line numbers
grep -n "search_term" file.txt

# Show only filenames with matches
grep -l "search_term" *.txt

# Invert match (show lines NOT containing pattern)
grep -v "exclude_this" file.txt

# Count matches
grep -c "search_term" file.txt

# Search with regular expressions
grep -E "pattern|alternative" file.txt

head - Display Beginning of File

# Show first 10 lines (default)
head file.txt

# Show first 20 lines
head -n 20 file.txt

# Show first 5 lines
head -5 file.txt

tail - Display End of File

# Show last 10 lines (default)
tail file.txt

# Show last 20 lines
tail -n 20 file.txt

# Follow file in real-time (useful for logs)
tail -f /var/log/syslog

# Follow with line numbers
tail -fn 50 logfile.txt

wc - Word Count

# Count lines, words, bytes
wc file.txt

# Count lines only
wc -l file.txt

# Count words only
wc -w file.txt

# Count characters only
wc -m file.txt

File Permissions Commands

chmod - Change File Permissions

# Make file executable
chmod +x script.sh

# Remove execute permission
chmod -x file

# Set specific permissions (rwxr-xr-x)
chmod 755 script.sh

# Owner read/write, group read, others none
chmod 640 private_file.txt

# Recursive permission change
chmod -R 755 directory/

# Symbolic notation
chmod u+x file     # Add execute for user (owner)
chmod g-w file     # Remove write for group
chmod o+r file     # Add read for others
chmod a+x file     # Add execute for all

chown - Change File Owner

# Change owner
sudo chown username file.txt

# Change owner and group
sudo chown username:groupname file.txt

# Recursive ownership change
sudo chown -R username:groupname directory/

# Change group only
sudo chown :groupname file.txt

Process Management Commands

ps - Show Running Processes

# Show processes for current user
ps

# Show all processes
ps aux

# Show process tree
ps auxf

# Show processes for specific user
ps -u username

# Sort by CPU usage
ps aux --sort=-%cpu | head

# Sort by memory usage
ps aux --sort=-%mem | head

top / htop - Monitor System Resources

# Interactive process monitor
top

# Better alternative (if installed)
htop

# Sort by CPU (in top): press Shift+P
# Sort by memory (in top): press Shift+M
# Kill process (in top): press k, then enter PID
# Quit: press q

kill - Terminate Processes

# Graceful termination (SIGTERM)
kill PID

# Force kill (SIGKILL)
kill -9 PID

# Kill by process name
killall process_name

# Kill all processes of a user
sudo pkill -u username

System Information Commands

uname - System Information

# Show all information
uname -a

# Show kernel name
uname -s

# Show kernel version
uname -r

# Show machine hardware name
uname -m

df - Disk Space Usage

# Show disk usage
df

# Human-readable format
df -h

# Show specific filesystem
df -h /home

# Show inodes
df -i

du - Directory Size

# Show directory size
du -sh directory/

# Show sizes of all subdirectories
du -h directory/

# Show top 10 largest directories
du -h / | sort -rh | head -10

# Show size of current directory
du -sh .

free - Memory Usage

# Show memory usage
free

# Human-readable format
free -h

# Show in megabytes
free -m

# Continuous monitoring (updates every 2 seconds)
free -h -s 2

Networking Commands

ping - Test Network Connectivity

# Ping host
ping google.com

# Ping specific number of times
ping -c 4 google.com

# Ping with specific interval
ping -i 2 google.com

ip - Network Configuration

# Show all network interfaces
ip addr show

# Show routing table
ip route show

# Show specific interface
ip addr show eth0

# Brief output
ip -brief addr

wget - Download Files

# Download file
wget https://example.com/file.zip

# Download with custom name
wget -O custom_name.zip https://example.com/file.zip

# Continue interrupted download
wget -c https://example.com/large_file.iso

# Download in background
wget -b https://example.com/file.zip

curl - Transfer Data

# Download file
curl -O https://example.com/file.zip

# Save with custom name
curl -o custom_name.zip https://example.com/file.zip

# Follow redirects
curl -L https://example.com

# Show HTTP headers
curl -I https://example.com

# POST request with data
curl -X POST -d "param=value" https://api.example.com

Package Management Commands

Ubuntu / Debian (apt)

# Update package lists
sudo apt update

# Upgrade all packages
sudo apt upgrade

# Full upgrade (handles dependencies better)
sudo apt full-upgrade

# Install package
sudo apt install package-name

# Remove package
sudo apt remove package-name

# Remove package and config files
sudo apt purge package-name

# Search for packages
apt search keyword

# Show package information
apt show package-name

# Remove unnecessary packages
sudo apt autoremove

# Clean package cache
sudo apt clean

Fedora (dnf)

# Update all packages
sudo dnf upgrade

# Install package
sudo dnf install package-name

# Remove package
sudo dnf remove package-name

# Search packages
dnf search keyword

# Show package info
dnf info package-name

# List installed packages
dnf list installed

Arch Linux (pacman)

# Update system
sudo pacman -Syu

# Install package
sudo pacman -S package-name

# Remove package
sudo pacman -R package-name

# Remove package and dependencies
sudo pacman -Rs package-name

# Search packages
pacman -Ss keyword

# Show package info
pacman -Si package-name

# List installed packages
pacman -Q

Command Chaining & Shortcuts

Operators

# Run commands sequentially
command1 ; command2

# Run second command only if first succeeds
command1 && command2

# Run second command only if first fails
command1 || command2

# Pipe output to another command
command1 | command2

# Redirect output to file (overwrite)
command > file.txt

# Redirect output to file (append)
command >> file.txt

# Redirect stderr to stdout
command 2>&1

# Redirect both stdout and stderr to file
command &> file.txt

Keyboard Shortcuts

• Ctrl+C: Kill running process
• Ctrl+Z: Suspend process (resume with fg)
• Ctrl+D: Exit current shell / EOF
• Ctrl+L: Clear screen (same as clear)
• Ctrl+A: Move to beginning of line
• Ctrl+E: Move to end of line
• Ctrl+U: Delete from cursor to beginning
• Ctrl+K: Delete from cursor to end
• Ctrl+R: Search command history
• Tab: Auto-complete file/command names
• ↑/↓: Navigate command history

Works On

• Ubuntu (all versions)
• Debian (all versions)
• Fedora (all versions)
• Arch Linux
• Linux Mint
• Any Linux distribution with bash shell