Skip to content

Linux System Commands Documentation

Introduction

Linux provides a powerful command-line interface that allows users to interact with the system efficiently. This documentation covers essential Linux commands and their explanations.

File and Directory Management

ls

  • Usage: ls [options] [directory]
  • Description: Lists files and directories in the specified directory.
  • Example: 
    ls -la
    Lists all files including hidden ones in long format.

cd

  • Usage: cd [directory]
  • Description: Changes the current working directory.
  • Example: 
    cd /var/www
    Navigates to the /var/www directory.

pwd

  • Usage: pwd
  • Description: Prints the current working directory.
  • Example: 
    pwd
    Displays the full path of the current directory.

mkdir

  • Usage: mkdir [directory_name]
  • Description: Creates a new directory.
  • Example: 
    mkdir new_folder
    Creates a directory named new_folder.

rm

  • Usage: rm [options] [file/directory]
  • Description: Removes files or directories.
  • Example: 
    rm -r my_folder
    Recursively removes my_folder and its contents.

User Management

whoami

  • Usage: whoami
  • Description: Displays the current logged-in user.

id

  • Usage: id [username]
  • Description: Shows user ID (UID) and group ID (GID).

sudo

  • Usage: sudo [command]
  • Description: Executes a command as a superuser.

Process Management

ps

  • Usage: ps aux
  • Description: Displays running processes.

kill

  • Usage: kill [PID]
  • Description: Terminates a process by its process ID.

htop

  • Usage: htop
  • Description: Interactive process viewer.

systemctl

  • Usage: systemctl [action] [service]
  • Description: Manages system services.
  • Example: 
    systemctl restart apache2
    Restarts the Apache service.

service

  • Usage: service [service_name] [action]
  • Description: Controls system services.
  • Example: 
    service nginx status
    Shows the status of the Nginx service.

Networking

ifconfig

  • Usage: ifconfig
  • Description: Displays network interface information.

ping

  • Usage: ping [hostname/IP]
  • Description: Checks connectivity to a host.

wget

  • Usage: wget [URL]
  • Description: Downloads files from the internet.

ssh

  • Usage: ssh [user]@[host]
  • Description: Connects to a remote server via SSH.
  • Example: 
    ssh user@192.168.1.1
    Connects to the server at 192.168.1.1 as user.

scp

  • Usage: scp [file] [user]@[host]:[destination]
  • Description: Securely copies files between local and remote machines.
  • Example: 
    scp myfile.txt user@192.168.1.1:/home/user/
    Copies myfile.txt to the remote server.

rsync

  • Usage: rsync -avz [source] [destination]
  • Description: Synchronizes files between local and remote locations efficiently.
  • Example: 
    rsync -avz /local/path/ user@remote:/remote/path/
    Synchronizes /local/path/ to /remote/path/ on the remote server.

System Monitoring

top

  • Usage: top
  • Description: Displays real-time system performance.

df

  • Usage: df -h
  • Description: Shows disk space usage.

free

  • Usage: free -m
  • Description: Displays memory usage.

uptime

  • Usage: uptime
  • Description: Shows how long the system has been running.

netstat

  • Usage: netstat -tulnp
  • Description: Displays active network connections.

File Permissions

chmod

  • Usage: chmod [permissions] [file]
  • Description: Changes file permissions.
  • Example: 
    chmod 755 script.sh
    Grants execute permissions.

chown

  • Usage: chown [owner]:[group] [file]
  • Description: Changes file owner and group.

Conclusion

These commands provide a solid foundation for working with Linux systems. Understanding and mastering them will help you efficiently manage files, users, processes, and system resources.