File System & Permissions Essentials

Linux organizes everything as a tree of files and directories. You'll learn the hierarchy, how to manage files, and how permissions control access.

At the very top sits the root directory, written as a single /. Every path on the server branches off from here.

A few key directories live under root: /bin for core commands, /etc for config, /home for users, /var for logs and variable data. Knowing them speeds you up.

mkdir makes a new directory. Let's create a folder named projects right where you are.

touch creates an empty file (and updates timestamps too). Let's drop a report.txt inside your projects folder.

mv moves files between locations — and renaming is just moving in place. Let's rename report.txt to final_report.txt.

Linux permissions control access by user, group, and others, each with read (r), write (w), and execute (x) — shown as strings like -rwxr-xr--.

chmod sets permissions, often in octal: r=4, w=2, x=1, summed per user type. So chmod 755 gives rwxr-xr-x — full for owner, read+execute for the rest.

Let's see chmod in action: create a script, then lock it down so only the owner can run it while the group just reads.

chown changes a file's owner and group (usually with sudo). Use user, :group, or user:group to set exactly who controls it.

Consider a file named data.log. You want the owner to have full read, write, and execute permissions, the group to have read and execute, and others to have only read permission.

Solid work! You learned the filesystem tree, key directories, file commands like mkdir and mv, and how chmod and chown control access. Core admin skills, locked in.