Essential Linux Commands and Their Functions every DevOps Engineer should know.

1. File System Operations
- ls: List files and directories
- cd: Change to another directory
- mkdir: Create new directories
- rm: Remove files or directories

2. File Permissions
- chmod: Change file permissions
- chown: Change file ownership
- chgrp: Change the group ownership of files and directories

3. Process Management
- ps: Show running processes
- kill: Terminate a process
- top: Monitor active processes

4. Networking
- ifconfig: Configure network interfaces
- ping: Test network connectivity, verifies if a host is responding and reachable
- netstat: Display network connections

5. System Information
- uname: Get system details
- hostname: Display or set system name
- df: Check disk space usage

6. Package Management
- apt: Manage packages on Debian-based systems
- yum: Manage packages on RPM-based systems
- dpkg: Handle Debian packages

7. Shell Scripting
- bash: GNU Bourne-Again SHell
- echo: Print text or variables to the terminal
- grep: Search for text patterns in files

8. User and Group Management
- useradd: Add a new user
- userdel: Delete a user
- passwd: Change user passwords

9. File Transfer
- scp: Securely copy files between hosts
- rsync: Sync files between locations
- wget: Download files from the internet

10. System Services
- systemctl: Control systemd services
- service: Run System V init scripts
- chkconfig: Enable or disable services