Intro

Intro

Control the running system under systemd: units, journals, kernel parameters, reboot/shutdown, transient jobs, sessions, modules, and container CLI (podman).

Commands in this part

Command	Role
systemctl	systemctl is the primary interface to systemd: start/stop units, enable on boot, inspect status, and list dependencies.
journalctl	journalctl queries the systemd journal — structured logs from the kernel, services, and many applications.
sysctl	sysctl reads and writes kernel parameters exposed under /proc/sys/.
shutdown	shutdown schedules a system power-off, halt, or reboot and notifies logged-in users.
reboot	reboot restarts the system.
podman	podman is a daemonless OCI container engine with a CLI largely compatible with Docker.
systemd-run	systemd-run creates transient units on the fly: one-shot commands, background services, or temporary timers without…
systemd-analyze	systemd-analyze diagnoses boot performance and unit graphs: how long boot took, which units delayed it, whether unit…
loginctl	loginctl manages systemd-logind seats, sessions, and users: who is logged in, idle hints, kill sessions, and…
modprobe	modprobe loads and unloads kernel modules, resolving dependencies via modules.dep — preferred over raw insmod/rmmod…

Suggested starting points

1. Services: systemctl status/start/enable; logs: journalctl.
2. Kernel tunables: sysctl; modules: modprobe.
3. Power: shutdown/reboot (prefer coordinated maintenance).
4. Ad-hoc units/timers: systemd-run; boot analysis: systemd-analyze.
5. User sessions / linger: loginctl.
6. Containers: podman.

Related parts

• Scheduling — cron vs timers
• Logging — classic log tools alongside the journal
• Processes and jobs — when a unit is really a process tree

Continue with the individual command pages in this part.