3System Administration

• 3.1Account Management

  Learn user and group management: useradd, userdel, usermod, groupadd, groupdel, groupmod, defaults (/etc/default/useradd) and the skeleton (/etc/skel/), the account databases (/etc/passwd, /etc/shadow, /etc/group), password management with passwd, and verification with getent and id.

• 3.2Job Scheduling

  Learn periodic and one-shot scheduling: cron (crontab syntax, /var/spool/cron/, /etc/crontab, /etc/cron.d/, cron.{hourly,daily,weekly,monthly}), one-time at (atq, atrm), catch-up runs with anacron (/etc/anacrontab), and access control (/etc/cron.allow, /etc/cron.deny, /etc/at.allow, /etc/at.deny).

• 3.3Localization and Internationalization

  Learn language and regional settings: internationalization (i18n) vs localization (l10n), locales and their variables (LANG, LC_ALL, LC_*), the locale command, character encodings (ASCII, Unicode, UTF-8, ISO-8859, ISO-2022-JP) with iconv conversion, and why LANG=C helps in scripts.