7.2 KiB
7.2 KiB
Linux Essential Commands – Cheat Sheet
Each block groups related commands and includes inline comments so it can be copied and pasted as a whole.
1. Navigation & Help
# Show current directory
pwd
# List files (basic / long / including hidden)
ls
ls -l # long listing (permissions, owner, size, date)
ls -a # include hidden files (starting with .)
# Change directory
cd /path/to/dir
cd ~ # go to home directory
cd .. # go up one level
# Command help
man ls # full manual page
ls --help # quick help for a command
2. Files & Directories
# Create or update an empty file
touch file.txt
# Copy files and directories
cp source.txt dest.txt
cp -r src_dir/ dest_dir/ # copy directory recursively
# Move or rename
mv oldname.txt newname.txt
mv file.txt /target/dir/
# Remove files and directories
rm file.txt # remove file
rm -r dir_to_remove/ # remove directory recursively
rm -rf dir_to_force/ # force remove (use with care)
# Create directories
mkdir new_dir
mkdir -p a/b/c # create nested directories
3. Viewing & Searching Content
# View file content
cat file.txt # print whole file
less file.txt # scrollable view (quit with 'q')
# View start / end of a file
head file.txt # first 10 lines
head -n 20 file.txt # first 20 lines
tail file.txt # last 10 lines
tail -f logfile.log # follow log in real time
# Search text
grep "pattern" file.txt # search in single file
grep -r "pattern" /path/dir # recursive in directory
grep -ri "pattern" /path/dir # recursive and case-insensitive
4. Permissions & Ownership
# View permissions and ownership
ls -l /path/to/file_or_dir
# Change permissions
chmod 644 file.txt # owner read/write, group/others read
chmod 600 secret.txt # owner read/write only
chmod +x script.sh # add execute bit
# Change owner and group
chown user:group file.txt
chown -R user:group /path/to/dir # recursive
5. Users, Groups & sudo (Debian/Ubuntu style)
# Identify current user and groups
whoami
id # show UID, GID, and groups
# Run a command as root (if allowed)
sudo command # run single command with privileges
# User management (Debian/Ubuntu)
sudo adduser newuser # interactive user creation
sudo passwd newuser # set or change password
# Add user to an additional group
sudo usermod -aG sudo newuser # grant sudo rights (example)
sudo usermod -aG docker newuser # allow use of docker group
6. Processes & System Monitoring
# List processes
ps aux # all processes with details
# Real-time monitoring
top # built-in monitor
htop # improved top (if installed)
# Kill a process by PID
kill 1234 # ask process to terminate
kill -9 1234 # force kill (SIGKILL)
# Jobs in current shell
jobs # list background jobs
fg %1 # bring job 1 to foreground
bg %1 # send job 1 to background
7. Services & Logs (systemd)
# Service management (systemd)
sudo systemctl status nginx.service # check status
sudo systemctl start nginx.service # start service
sudo systemctl stop nginx.service # stop service
sudo systemctl restart nginx.service # restart service
sudo systemctl enable nginx.service # start at boot
sudo systemctl disable nginx.service # do not start at boot
# View logs with journalctl
sudo journalctl -u nginx.service # logs for one unit
sudo journalctl -u nginx.service -f # follow logs
sudo journalctl -b # logs from current boot
8. System Information & Resources
# Basic system info
uname -a # kernel and system info
hostname # system hostname
# Disk and filesystem usage
df -h # disk usage by filesystem
du -sh /path/to/dir # summary size of a directory
# Memory and swap usage
free -h
# Uptime and logged-in users
uptime
w # who is logged in and what they do
9. Networking Basics
# IP addresses and links
ip a # show interfaces and addresses
ip r # routing table
# Connectivity tests
ping 8.8.8.8 # test raw connectivity
ping example.com # test DNS + connectivity
# Open/listening ports
sudo ss -tulpn # TCP/UDP sockets with PIDs
# HTTP requests and downloads
curl https://example.com # simple HTTP GET
wget https://example.com/file.iso # download file
10. Storage & Mounts (Conceptual Commands)
# List block devices (disks/partitions)
lsblk # tree view of devices and mount points
# Show filesystems and usage
df -h # mounted filesystems
# Show current mounts
mount | grep "/"
# View /etc/fstab (persistent mounts)
sudo nano /etc/fstab # edit with care
11. Archives & Compression
# Create and extract tar archives
tar -cf archive.tar file1 dir2 # create tar
tar -xf archive.tar # extract tar
# Create and extract compressed tar.gz
tar -czf archive.tar.gz file1 dir2 # create tar.gz
tar -xzf archive.tar.gz # extract tar.gz
# Zip archives
zip archive.zip file1 file2 # create zip
unzip archive.zip # extract zip
12. Package Management (Debian / Ubuntu)
# Update package lists and upgrade
sudo apt update # refresh package index
sudo apt upgrade # upgrade installed packages
# Install, remove, purge packages
sudo apt install htop # install package
sudo apt remove htop # remove package (keep config)
sudo apt purge htop # remove package + config
# Search and inspect packages
apt search nginx # search in repositories
apt show nginx # show details
13. SSH & Remote Access
# Connect to a remote host
ssh user@server.example.com
# Use a specific key and port
ssh -i ~/.ssh/id_ed25519 -p 2222 user@server.example.com
# Copy files over SSH
scp file.txt user@server.example.com:/remote/path/
scp -r dir/ user@server.example.com:/remote/path/
14. Shutdown & Reboot
# Shutdown and reboot (systemd)
sudo shutdown now # immediate shutdown
sudo shutdown -r now # immediate reboot
sudo shutdown +5 # shutdown in 5 minutes
sudo reboot # reboot system
sudo poweroff # power off system
sudo systemctl reboot # reboot via systemd
sudo systemctl poweroff # power off via systemd
15. Shell Shortcuts (Bash)
Ctrl + C– Cancel current commandCtrl + D– Logout / send EOFCtrl + R– Search in command history↑/↓– Navigate command historyTab– Auto-completion