Linux Commands Cheatsheet

# Current directory
pwd

# List files and directories
ls              # Basic list
ls -la          # Detailed list including hidden
ls -lh          # Human readable sizes
ls -R           # Recursive list

# Change directory
cd /path        # Absolute path
cd ./path       # Relative path
cd ..           # Parent directory
cd ~            # Home directory
cd -            # Previous directory

# Find files
find . -name "*.js"     # Find by name
find . -type f -mtime -7  # Files modified in last 7 days
find . -size +10M        # Files larger than 10MB

# Search file content
grep "search" file.txt   # Search in file
grep -r "search" .      # Search recursively
grep -i "CASE" file.txt # Case insensitive

# Create
mkdir directory           # Create directory
mkdir -p path/to/dir     # Create with parents
touch file.txt           # Create/update file

# Copy
cp file.txt backup.txt   # Copy file
cp -r dir1 dir2         # Copy directory
cp -p file.txt backup   # Preserve permissions

# Move/Rename
mv file.txt newname.txt  # Rename file
mv file.txt ../          # Move file
mv dir1 dir2            # Move directory

# Delete
rm file.txt             # Remove file
rm -r directory         # Remove directory
rm -rf directory        # Force remove
rmdir empty_dir         # Remove empty dir

# Permissions
chmod 755 file.txt      # Change permissions
chown user:group file   # Change ownership

# APT (Debian/Ubuntu)
apt update              # Update package list
apt install package     # Install package
apt remove package      # Remove package
apt upgrade             # Upgrade all packages

# NPM
npm install            # Install dependencies
npm install package    # Install package
npm update            # Update packages
npm run script        # Run script

# Git
git clone repo_url     # Clone repository
git pull origin main   # Pull updates
git status            # Check status
git add .             # Stage changes
git commit -m "msg"   # Commit changes
git push origin main  # Push changes

# Docker
docker ps             # List containers
docker images         # List images
docker-compose up     # Start services
docker-compose down   # Stop services

# View processes
ps aux               # List all processes
top                  # Interactive process viewer
htop                # Enhanced top

# Process control
kill PID            # Kill process
killall process     # Kill by name
pkill pattern       # Kill by pattern

# Background jobs
command &           # Run in background
jobs               # List background jobs
fg %1              # Bring to foreground
bg %1              # Send to background

# Services
systemctl start service    # Start service
systemctl stop service     # Stop service
systemctl restart service  # Restart service
systemctl status service   # Check status

# Network info
ifconfig            # Network interfaces
ip addr             # IP addresses
netstat -tuln       # Open ports
ss -tuln            # Socket statistics

# Connectivity
ping domain.com     # Test connectivity
curl domain.com     # HTTP request
wget url           # Download file
dig domain.com     # DNS lookup
nslookup domain    # Name server lookup

# SSH
ssh user@host              # Connect to host
ssh-keygen                 # Generate SSH key
ssh-copy-id user@host      # Copy SSH key
scp file user@host:/path   # Secure copy

# Firewall
ufw status                # Check firewall
ufw allow 80/tcp         # Allow port
ufw deny 80/tcp          # Block port
ufw enable/disable       # Toggle firewall

# Apache
apache2ctl -t            # Test config
apache2ctl -S            # Show vhosts
systemctl restart apache2  # Restart

# Nginx
nginx -t                 # Test config
nginx -s reload          # Reload config
systemctl restart nginx  # Restart

# Logs
tail -f /var/log/nginx/access.log  # Live log
tail -f /var/log/apache2/error.log # Error log
journalctl -u nginx     # Service logs
grep ERROR /var/log/nginx/*.log    # Search logs

# System resources
free -h              # Memory usage
df -h               # Disk usage
du -sh directory    # Directory size
iostat              # IO statistics
vmstat              # Virtual memory stats

# CPU info
cat /proc/cpuinfo   # CPU details
uptime              # Load average
lscpu              # CPU architecture

# System monitoring
htop               # Interactive monitor
nmon               # Performance monitor
iotop              # IO monitor
nethogs            # Network monitor

# Log monitoring
tail -f /var/log/syslog     # System log
dmesg                       # Kernel log
journalctl -f              # System journal

# Disk cleanup
apt clean                  # Clean package cache
apt autoremove            # Remove unused
rm -rf ~/.cache/*         # Clear user cache
find /tmp -type f -delete # Clear temp files

# System updates
apt update                # Update repos
apt upgrade               # Upgrade packages
apt dist-upgrade         # Smart upgrade
do-release-upgrade       # Version upgrade

# Backup
tar -czf backup.tar.gz dir/  # Create archive
tar -xzf backup.tar.gz      # Extract archive
rsync -av source/ dest/     # Sync directories
dd if=/dev/sda of=disk.img  # Disk image