Useful Linux Command Reference for Beginners

Linux Command Dictionary: A Beginner’s Guide

1. Getting Started

• Terminal: The command-line interface where you type Linux commands.
• Command: A typed instruction to the computer (e.g., ls).
• Flag: An option that changes a command’s behavior (e.g., -l).
• Argument: The target of the command (e.g., a file or directory name).

2. File & Directory Management

• ls – Lists files and folders in the current directory.
• cd – Changes the current directory.
• pwd – Displays the full path of your current directory.
• mkdir – Creates a new folder.
• touch – Creates an empty file.
• rm – Deletes files or folders.
• mv – Moves or renames files or folders.
• cp – Copies files or folders.
• tree – Shows folder structure in tree form (may need to install).

3. Viewing & Editing Files

• cat – Displays the full contents of a file.
• less – Lets you scroll through a file one screen at a time.
• head – Shows the first 10 lines of a file.
• tail – Shows the last 10 lines of a file.
• nano – Simple built-in text editor in the terminal.
• wc – Word/line/character count of a file.
• file – Identifies the file type.

4. File Permissions & Ownership

• chmod – Changes who can read/write/execute a file.
• chown – Changes the owner of a file or directory.
• ls -l – Shows detailed file info including permissions.
• umask – Displays or sets default file permissions.

5. Searching & Finding

• find – Searches for files/folders by name or property.
• grep – Finds lines in files that match text patterns.
• locate – Quickly finds file paths (requires updated database).
• which – Shows the full path of a command.

6. Package Management

• apt / apt-get – Installs packages on Debian/Ubuntu.
• yum / dnf – Used on Red Hat-based systems.
• pacman – Package manager for Arch Linux.
• snap – Manages Snap universal packages.
• flatpak – Manages Flatpak universal apps.

7. System Monitoring & Process Control

• top – Real-time process and resource monitor.
• htop – Advanced version of top (requires install).
• ps – Displays running processes.
• kill / killall – Stops a running process by PID or name.
• uptime – Shows how long the system has been running.
• free -h – Displays memory usage in human-readable format.
• df -h – Shows available disk space.
• du -sh * – Shows size of each item in current folder.

8. Networking Basics

• ping – Tests network connection to another machine.
• ip a – Shows network interface details.
• ifconfig – Legacy tool for network info (sometimes not installed).
• netstat -tuln – Lists open ports and listening services.
• curl – Downloads content from a URL (or sends data).
• wget – Simple download utility.
• scp – Securely copies files between machines via SSH.
• ssh – Connects to another machine securely over a network.

9. Archiving & Compression

• tar – Archives or extracts folders into .tar files.
• gzip / gunzip – Compresses or decompresses files (.gz).
• zip / unzip – Works with standard .zip files.
• 7z – Uses the high-compression 7-Zip format.

10. User Management

• adduser / useradd – Adds new users to the system.
• passwd – Changes a user’s password.
• whoami – Prints your current username.
• su / sudo – Switches user or runs command as root/admin.

11. Nano Editor Basics

• nano filename – Opens a file in the nano editor.
• Ctrl+O – Save the file.
• Ctrl+X – Exit nano.
• Ctrl+K / Ctrl+U – Cut and uncut (paste) lines.
• Ctrl+W – Search in file.
• Ctrl+\ – Find and replace text.

12. System & Shell Info

• uname -a – Shows detailed system info.
• echo $SHELL – Displays the shell you’re using.
• env – Lists all environment variables.
• history – Shows recently used commands.
• alias – Creates a custom command shortcut.
• man – Displays the full manual for a command.
• --help – Provides a quick summary of a command’s options.

13. Fun & Useful Extras

• cowsay – Displays a talking ASCII cow (just for fun).
• fortune – Prints a random quote or message.
• neofetch – Shows system info in a flashy way.
• cal – Displays a calendar.
• date – Displays current system time and date.