CHAPTER 02 · OPERATING SYSTEMS

Linux essentials

A small set of commands, used carefully, makes Linux easier to understand and administer.

Linux uses a single directory tree rooted at /. Check your location before changing files.

pwd; ls -lah; cd ~/Documents

Files and folders

Create folders with parents, copy cautiously, and use interactive flags where overwriting would be risky.

mkdir -p projects/handbook/assets; cp -i notes.md backup/notes.md; mv draft.md final.md

Warning: Recursive deletion can permanently remove data. Confirm the full target path first.

Permissions are owner, group, and others. r is read, w is write, and x is execute.

ls -l report.txt; chmod 600 ~/.ssh/id_ed25519; chmod u+x backup.sh

Use normal termination before forceful termination, and manage services through the service manager where possible.

ps aux; top; systemctl status ssh

Experiment inside a test folder in your home directory. Check manual pages with man command before running unfamiliar administrative commands.