# systemctl — Control systemd Services and Units > Practical guide to systemctl — start, stop, enable and inspect services, manage units, targets and timers, and control system state. Source: https://www.jpkc.com/db/en/cheatsheets/shell-system/systemctl/ systemctl is the central tool for controlling the systemd init and service manager – from individual services to the entire system state. You start, stop and reload services, enable them for automatic startup, check their status, and work with units, targets, timers and logs. This guide walks you through the commands you actually reach for in everyday server work, from a quick `restart` to boot analysis with `systemd-analyze`. ## Service Control `systemctl start ` — Start a service immediately. ```bash systemctl start nginx ``` `systemctl stop ` — Stop a running service. ```bash systemctl stop nginx ``` `systemctl restart ` — Stop and then start a service. Causes a brief downtime. ```bash systemctl restart nginx ``` `systemctl reload ` — Reload configuration without stopping the service (zero downtime, if supported). ```bash systemctl reload nginx ``` `systemctl reload-or-restart ` — Reload if the service supports it, otherwise restart. ```bash systemctl reload-or-restart php-fpm ``` `systemctl try-restart ` — Restart a service only if it is currently running. ```bash systemctl try-restart nginx ``` `systemctl kill ` — Send a signal to a service's processes. Default signal is SIGTERM. ```bash systemctl kill nginx ``` `systemctl kill -s SIGKILL ` — Force kill a service by sending SIGKILL to all its processes. ```bash systemctl kill -s SIGKILL stuck-service ``` ## Enable & Disable (Boot Behavior) `systemctl enable ` — Enable a service to start automatically at boot. ```bash systemctl enable nginx ``` `systemctl disable ` — Disable a service from starting at boot. ```bash systemctl disable nginx ``` `systemctl enable --now ` — Enable at boot and start immediately in one command. ```bash systemctl enable --now nginx ``` `systemctl disable --now ` — Disable at boot and stop immediately in one command. ```bash systemctl disable --now nginx ``` `systemctl is-enabled ` — Check if a service is enabled for automatic start at boot. ```bash systemctl is-enabled nginx ``` `systemctl reenable ` — Disable and re-enable a service. Useful after changing the [Install] section. ```bash systemctl reenable nginx ``` `systemctl mask ` — Completely prevent a service from being started (even manually). Links unit to /dev/null. ```bash systemctl mask bluetooth ``` `systemctl unmask ` — Remove the mask and allow the service to be started again. ```bash systemctl unmask bluetooth ``` ## Service Status & Inspection `systemctl status ` — Show detailed status including state, PID, memory usage, and recent log lines. ```bash systemctl status nginx ``` `systemctl is-active ` — Check if a service is currently running. Returns active or inactive. ```bash systemctl is-active nginx ``` `systemctl is-failed ` — Check if a service has failed. ```bash systemctl is-failed nginx ``` `systemctl show ` — Show all properties of a service in key=value format. ```bash systemctl show nginx ``` `systemctl show -p ` — Show a specific property of a service. ```bash systemctl show nginx -p MainPID ``` `systemctl show -p ActiveState,SubState` — Show multiple specific properties at once. ```bash systemctl show nginx -p ActiveState,SubState,MainPID ``` `systemctl cat ` — Display the full unit file content of a service. ```bash systemctl cat nginx ``` `systemctl help ` — Open the man page associated with a service (if available). ```bash systemctl help sshd ``` ## Listing Units `systemctl list-units` — List all loaded and active units. ```bash systemctl list-units ``` `systemctl list-units --type=service` — List only service units. ```bash systemctl list-units --type=service ``` `systemctl list-units --state=running` — List only currently running units. ```bash systemctl list-units --state=running ``` `systemctl list-units --state=failed` — List all units that have failed. ```bash systemctl list-units --state=failed ``` `systemctl list-units --all` — List all units including inactive ones. ```bash systemctl list-units --all ``` `systemctl list-unit-files` — List all installed unit files with their enabled/disabled state. ```bash systemctl list-unit-files ``` `systemctl list-unit-files --type=service` — List only service unit files with their state. ```bash systemctl list-unit-files --type=service ``` `systemctl list-unit-files --state=enabled` — List only enabled unit files. ```bash systemctl list-unit-files --state=enabled ``` ## Dependencies & Order `systemctl list-dependencies ` — Show a tree of units that a service depends on. ```bash systemctl list-dependencies nginx ``` `systemctl list-dependencies --reverse` — Show which units depend on (require) this service. ```bash systemctl list-dependencies nginx --reverse ``` `systemctl list-dependencies --before` — Show units that this service starts before. ```bash systemctl list-dependencies nginx --before ``` `systemctl list-dependencies --after` — Show units that this service starts after. ```bash systemctl list-dependencies nginx --after ``` ## Unit File Management `systemctl edit ` — Create a drop-in override file for a service (opens editor). Changes survive package updates. ```bash systemctl edit nginx ``` `systemctl edit --full ` — Edit the full unit file directly (not a drop-in). Overrides will NOT survive package updates. ```bash systemctl edit --full nginx ``` `systemctl daemon-reload` — Reload systemd manager configuration after modifying unit files. Required after any manual edit. ```bash systemctl daemon-reload ``` `systemctl revert ` — Remove all local customizations (drop-ins) and revert to the vendor unit file. ```bash systemctl revert nginx ``` `systemd-analyze verify ` — Check a unit file for syntax errors and common issues. ```bash systemd-analyze verify /etc/systemd/system/my-app.service ``` ## Timers (Cron Replacement) `systemctl list-timers` — List all active timers with their next and last trigger times. ```bash systemctl list-timers ``` `systemctl list-timers --all` — List all timers including inactive ones. ```bash systemctl list-timers --all ``` `systemctl start ` — Start a timer immediately. ```bash systemctl start backup.timer ``` `systemctl enable --now ` — Enable a timer to persist across reboots and start it now. ```bash systemctl enable --now backup.timer ``` `systemctl status ` — Show timer status including next scheduled run. ```bash systemctl status backup.timer ``` `systemd-analyze calendar ''` — Test and parse a calendar expression to see when it would trigger. ```bash systemd-analyze calendar 'Mon..Fri *-*-* 06:00:00' ``` `systemd-run --on-calendar='' ` — Create a transient timer that runs a command on a schedule. ```bash systemd-run --on-calendar='*-*-* 02:00:00' /usr/local/bin/backup.sh ``` `systemd-run --on-active=