This is a quick reference for common Linux commands and configurations — organized into categories. Use the menu above to switch between topics.
Name: Ivan Lazic
Email: code@mycipher.net
Address: 11407 Selevac, Serbia
ls -l # List files in long format
cp a b # Copy a to b
mv a dir/ # Move or rename file
rm file # Delete file
mkdir folder # Create directory
rmdir folder # Remove directory
chmod 755 file # rwxr-xr-x
chown user:group file # Change owner
umask 022 # Default permission mask
tar -czf archive.tar.gz folder/ # Create tar.gz
tar -xzf archive.tar.gz # Extract tar.gz
zip -r archive.zip folder/ # Create zip
unzip archive.zip # Extract zip
find / -name "*.conf" # Search files by name
grep "keyword" file.txt # Search text in file
grep -r "pattern" /etc # Recursive grep
df -h # Disk space usage
du -sh folder/ # Folder size
lsblk # List block devices
mount /dev/sdX /mnt # Mount drive
adduser name # Create new user
deluser name # Delete user
passwd name # Change password
su - user # Switch user
whoami # Show current user
groupadd admins # Create group
usermod -aG admins ivan # Add user to group
groups ivan # Show user groups
visudo # Edit sudoers
sudo command # Run with root privileges
id # Display UID and groups
who # Who is logged in
w # Show current users
last # Last logins
finger user # Show user info
ifconfig # Show interfaces (deprecated)
ip a # Show IPs
ip link set eth0 up # Enable interface
dhclient eth0 # Request IP from DHCP
ping 8.8.8.8 # Test connectivity
ping -c 4 google.com # 4 pings only
traceroute host # Show route
curl ifconfig.me # Show public IP
netstat -tulnp # Show listening ports
ss -tuln # Show open sockets
nslookup host # DNS lookup
dig host +short # DNS info
ufw status # Show firewall status
ufw allow 22/tcp # Allow SSH
ufw deny 80/tcp # Block port 80
iptables -L -v # Show rules
iftop # Live bandwidth
nload # Network traffic
tcpdump -i eth0 # Capture packets
/etc/fstab # Mount configuration
/etc/hosts # Hostname mapping
/etc/resolv.conf # DNS settings
/etc/hostname # System hostname
systemctl start nginx
systemctl enable ssh
systemctl status apache2
journalctl -xe
/etc/ssh/sshd_config
/etc/sudoers
/etc/pam.d/
grub-mkconfig -o /boot/grub/grub.cfg
update-initramfs -u