Category: Linux

Understand Linux boot stages and systemd units, distinguish active services from boot enablement, and inspect current-boot logs with systemctl and journalctl.

Compare APT on Debian or Ubuntu with DNF on Rocky Linux for searching, installing, updating, and removing packages, including repository and transaction checks.

Inspect Linux processes with ps, top, and pgrep, then safely pause, resume, and terminate a practice process while distinguishing shell jobs from services.

Learn to read file and directory permissions, practice chmod safely, and understand when to use sudo and how to diagnose access errors.

Understand UIDs, GIDs, primary and supplementary groups, and file ownership, then inspect them safely with id, groups, getent, ls, and stat.

Learn how Bash resolves commands and uses exit status with ;, &&, and ||, then distinguish aliases, shell variables, and exported environment variables.

Understand standard input, output, and error; practice file redirection and pipes; and learn why overwrite risk and redirection order matter.

Use diff and cmp to compare two files, read unified diff output, and distinguish a detected difference from an actual command error.

Practice searching, sorting, grouping, extracting, and counting text with grep, sort, uniq, cut, and wc, including reproducible output and key caveats.

Understand what PID and PPID mean, inspect parent-child process relationships with ps and pgrep, and safely terminate a process you started yourself.