The servers running the internet don't have a mouse. They run Linux. Knowing these commands distinguishes a "User" from an "Admin".
The program that takes your commands and gives them to the OS. If you see a $ prompt, you are talking to the shell.
The "God Mode" user. Can delete the entire operating system with one command. We use sudo to borrow Root's power temporarily.
In Linux, your hard drive is a file. Your mouse is a file. Your settings are files. If you can edit text files, you can configure anything.
| ls -lah | List all files (including hidden), detailed view, human readable sizes. |
| cd /var/log | Change Directory. Jump straight to a folder. |
| cat error.log | Print the full content of a file to the screen. |
| tail -f error.log | Watch the end of a file in real-time. Crucial for debugging live logs. |
| grep "error" file.txt | Search for a specific word inside a file. |
| sudo [cmd] | Run as Root. Required for restarting services or editing system configs. |
| systemctl restart nginx | Control background services (Start, Stop, Restart, Status). |
| ps aux | See every running process on the machine. |
| top | Task Manager. See CPU/RAM usage live. |
| df -h | Disk Free. Check how much hard drive space is left. |
| chmod 777 file | Change Mode. Sets read/write/execute permissions. (777 is dangerous!) |
| chown user:group file | Change Owner. Takes ownership of a file. |
| apt update | Refresh the list of available software. |
| apt install [package] | Download and install software (e.g., apt install nginx). |