100 Essential Linux Commands Every Developer Must Know

Whether you are a developer, system administrator, or cybersecurity professional, mastering the Linux command line is non-negotiable. This guide covers the 100 most important commands with practical examples.

File and Directory Operations

# Navigation
pwd                    # Print current directory
ls -la                 # List all files with details
ls -lh                 # Human-readable file sizes
cd /path/to/dir        # Change directory
cd ~                   # Go to home directory
cd -                   # Go to previous directory

# Create / Delete
mkdir -p dir/sub/dir   # Create nested directories
rmdir dirname          # Remove empty directory
rm -rf dirname         # Remove directory and contents (CAREFUL!)
touch filename.txt     # Create empty file
cp -r source/ dest/    # Copy directory recursively
mv oldname newname     # Move or rename
ln -s /target /link    # Create symbolic link

File Viewing and Editing

cat file.txt           # Display file content
less file.txt          # Page through file (q to quit)
head -20 file.txt      # Show first 20 lines
tail -20 file.txt      # Show last 20 lines
tail -f /var/log/syslog # Follow log file in real time
grep "pattern" file    # Search for pattern in file
grep -r "pattern" dir/ # Recursive search in directory
grep -i "pattern" file # Case-insensitive search
wc -l file.txt         # Count lines in file
diff file1 file2       # Compare two files
sort file.txt          # Sort lines alphabetically
sort -n file.txt       # Sort numerically
uniq file.txt          # Remove duplicate lines
cut -d',' -f1 file.csv # Extract first column from CSV

Process Management

ps aux                 # List all running processes
ps aux | grep nginx    # Find specific process
top                    # Live process monitor
htop                   # Better process monitor (install first)
kill PID               # Kill process by ID
kill -9 PID            # Force kill process
killall nginx          # Kill all processes by name
jobs                   # List background jobs
bg                     # Resume job in background
fg                     # Bring job to foreground
nohup command &        # Run command immune to hangups
command &              # Run command in background

File Permissions

chmod 755 file         # rwxr-xr-x
chmod 644 file         # rw-r--r--
chmod +x script.sh     # Add execute permission
chmod -R 755 dir/      # Recursive permission change
chown user:group file  # Change file owner
chown -R user dir/     # Recursive ownership change
ls -la                 # View permissions
umask 022              # Set default permissions

Networking Commands

ip addr                # Show IP addresses (modern)
ifconfig               # Show network interfaces (legacy)
ping -c 4 google.com   # Ping with 4 packets
traceroute google.com  # Trace network path
nslookup domain.com    # DNS lookup
dig domain.com         # Detailed DNS query
dig +short domain.com  # Quick DNS answer
curl https://site.com  # HTTP GET request
curl -I https://site.com # Headers only
wget https://file.zip  # Download file
ss -tuln               # Show open ports (modern)
netstat -tuln          # Show open ports (legacy)
iptables -L            # List firewall rules
ufw status             # Check UFW firewall status

Disk and System

df -h                  # Disk usage (human readable)
du -sh dir/            # Directory size
du -sh * | sort -h     # Sort directories by size
free -h                # RAM usage
uptime                 # System uptime and load
uname -a               # Kernel and OS info
lsb_release -a         # Linux distribution info
lscpu                  # CPU information
lsblk                  # List block devices
mount | grep /dev      # Show mounted filesystems
fdisk -l               # List disk partitions (root)

Archiving and Compression

tar -czvf archive.tar.gz dir/   # Create compressed archive
tar -xzvf archive.tar.gz        # Extract archive
tar -tzvf archive.tar.gz        # List archive contents
zip -r archive.zip dir/         # Create ZIP
unzip archive.zip                # Extract ZIP
gzip file.txt                   # Compress file
gunzip file.txt.gz               # Decompress file

Package Management

# Debian/Ubuntu/Kali
sudo apt update                  # Update package list
sudo apt upgrade -y              # Upgrade all packages
sudo apt install nginx           # Install package
sudo apt remove nginx            # Remove package
sudo apt autoremove              # Remove unused packages
dpkg -l | grep nginx             # Check if package installed

# CentOS/RHEL/AlmaLinux
sudo dnf update
sudo dnf install nginx
sudo dnf remove nginx

Bash Shortcuts

!!                     # Repeat last command
!nginx                 # Repeat last command starting with 'nginx'
Ctrl+R                 # Search command history
history | grep ssh     # Search history for ssh commands
alias ll='ls -la'      # Create command alias
echo              # Print PATH variable
export VAR=value       # Set environment variable
env                    # List all environment variables

Download our free Linux Commands Cheatsheet PDF from our Tools page — all 100 commands in a printable single-page reference card.