Important Files and Paths

System files and directories every Linux engineer encounters. Know where things live and what they contain.

Labs in this module

The Filesystem Hierarchy - The standard map of top-level directories on every Linux system. Read the root with ls /, learn what each floor is for (/etc for settings, /
/etc/group - Read the Linux group roster in /etc/group. The four colon-separated fields (name, password placeholder, GID, members), how the member list w
/etc/fstab - Read the filesystem table that mounts every disk at boot. The comment header, the six whitespace-separated fields on each entry (file system
/etc/os-release - Read a machine identity card with /etc/os-release. The KEY=VALUE format, the three load-bearing keys (PRETTY_NAME, ID, VERSION_ID), and how
/sys - Explore /sys, the virtual filesystem the kernel builds live from your hardware. The ten top-level drawers, the class grouping by device role
/proc - Read the live state of a running Linux machine through /proc, a virtual filesystem the kernel generates on demand. The numbered PID director
/etc/passwd - Read the account roster with cat /etc/passwd. The seven colon-separated fields (username, password placeholder x, UID, GID, comment, home, s
/etc/hosts - Read the local name table with cat /etc/hosts. What the file is for, the address-whitespace-name line shape, the two loopback lines that bot
/etc/hostname - Read the machine's own name from /etc/hostname. One line, one name, read at boot. Learn the file (persistent name) versus the hostname comma
Operation Know Your Machine - The Important Files module capstone mission. Survey an unfamiliar server by reading its own key files: the FHS root (ls /), the account list