Essential Linux Commands: A Practical Reference

Essential Linux Commands

File and Directory Management

• mkdir: Create a new directory.
• ls: List contents of a directory.
• rm: Remove files or directories (-r for recursive).
• cp: Copy files or directories.
• mv: Move or rename files or directories.
• cat: Display file contents or create files.
• less: View file contents one page at a time.
• head: Display the first 10 lines of a file.
• tail: Display the last 10 lines of a file.

System Information

• uname: Show system information (kernel, version, etc.).
• top: Display running processes and resource usage.
• df: Show disk space usage.
• df -h: Show disk usage in human-readable format.
• free: Display memory usage (RAM and swap).

File Creation and Editing

• touch: Create an empty file or update its timestamp.
• echo: Write text to a file or print to terminal.
• cat: Create or display file contents.
• nano: Open a simple terminal-based text editor.

Networking and Connectivity

• ip: Show or configure network interfaces.
• ping: Check connectivity to a network host.
• traceroute: Trace packet paths to a destination.
• netstat: Show network connections and statistics.
• nmap: Scan networks for hosts and open ports.
• tcpdump: Capture and display network packets.
• wireshark: GUI tool for analyzing network traffic.

File Searching and Compression

• grep: Search for patterns in files.
• tar: Archive files and directories (-cvf to create).
• zip: Compress files into a .zip archive.
• unzip: Extract files from a .zip archive.

User Management

• sudo adduser: Add a new user.
• sudo deluser: Remove a user.
• passwd: Change a user’s password.
• su: Switch to another user or superuser.
• apt: Manage packages (install, update, remove).
• apt-get: Alternative package manager (similar to apt).

Process and System Management

• killall: Kill processes by name.
• sudo systemctl: Manage system services (start, stop, restart).

Other Useful Commands

• history: Show previously executed commands.
• chmod: Change file permissions.
• chown: Change file ownership or group.
• sudo: Execute commands with elevated (root) privileges.
• man: Display the manual for a command.