systemd Services and Timers

Cargt images use systemd to start and supervise everything that runs on the board: Weston, Wi-Fi and Bluetooth bring-up, NetworkManager, SWUpdate and your own applications. Each of these is a unit, usually a .service file. This page covers the commands you need day to day. The examples are from an i.MX 93 00363 on the 00428 carrier, running a wrynose image.

Running Now vs. Starting at Boot 

Two separate questions apply to every service: is it running now (active), and does it start at boot (enabled)? Different commands change each one:

Command	Effect
`systemctl start <unit>`	Start it now. It does not start at the next boot unless it is enabled.
`systemctl stop <unit>`	Stop it now. If it is enabled, it starts again at the next boot.
`systemctl restart <unit>`	Stop and start it, for example after changing its configuration.
`systemctl reload <unit>`	Ask it to reread its configuration without stopping, for services that support it.
`systemctl enable <unit>`	Start it at every boot. It does not start it now.
`systemctl disable <unit>`	Stop starting it at boot. It does not stop it now.
`systemctl enable --now <unit>`	Enable it and start it now.
`systemctl disable --now <unit>`	Disable it and stop it now.

Check the two states with is-active and is-enabled, which print one word per unit:

root@imx93-cargt-00363-00428:~# systemctl is-active weston nxp-wifi swupdate
active
inactive
active
root@imx93-cargt-00363-00428:~# systemctl is-enabled weston nxp-wifi swupdate
enabled
enabled
enabled

nxp-wifi is enabled but inactive, and that is correct: it only loads the Wi-Fi driver at boot and then exits. weston and swupdate keep running.

systemctl status <unit> shows both states, the main process and the last log lines:

root@imx93-cargt-00363-00428:~# systemctl status swupdate
● swupdate.service - SWUpdate daemon
     Loaded: loaded (/usr/lib/systemd/system/swupdate.service; enabled; preset: enabled)
     Active: active (running) since Fri 2026-10-30 17:08:26 UTC; 20h ago
 Invocation: 88b7df9ed3754e6bad75b102363a4633
TriggeredBy: ● swupdate.socket
       Docs: https://github.com/sbabic/swupdate
             https://sbabic.github.io/swupdate
   Main PID: 616 (swupdate)
...

Loaded shows the unit file and whether it is enabled; Active shows whether it runs. TriggeredBy means a socket unit can also start it on demand.

Finding Problems 

systemctl is-system-running        # "running" when nothing has failed, else "degraded"
systemctl list-units --failed      # the units that failed
journalctl -u <unit> -b            # a unit's log since boot
systemctl reset-failed <unit>      # clear a failed state after fixing it

On a board where everything started:

root@imx93-cargt-00363-00428:~# systemctl is-system-running
running
root@imx93-cargt-00363-00428:~# systemctl list-units --failed
  UNIT LOAD ACTIVE SUB DESCRIPTION

0 loaded units listed.

systemctl list-unit-files --state=enabled lists what starts at boot. Debugging in Linux covers journalctl and the kernel log in more detail.

Turning a Service Off Completely 

A disabled service can still be started by another unit that needs it, or by its socket. mask prevents it from starting at all, until unmask:

systemctl mask --now <unit>
systemctl unmask <unit>

Use this, for example, to keep a service out of the way while you run the same program by hand.

Looking at and Changing a Unit 

systemctl cat prints a unit’s file, and any drop-in files that change it:

root@imx93-cargt-00363-00428:~# systemctl cat nxp-wifi
# /usr/lib/systemd/system/nxp-wifi.service
[Unit]
Description=NXP WiFi service
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/env modprobe moal mod_para=nxp/wifi_mod_para.conf drvdbg=0x00000000
ExecStartPost=/usr/bin/sleep 3

[Install]
WantedBy=multi-user.target

Do not edit files under /usr/lib/systemd: a software update replaces them. To change a setting, add a drop-in, which overrides only the lines it contains:

systemctl edit <unit>       # opens an editor for /etc/systemd/system/<unit>.d/override.conf
systemctl restart <unit>

systemctl edit reloads systemd for you. If you create or change unit files any other way, run systemctl daemon-reload before restarting the unit, or systemd keeps using the old version. To override a setting that can appear several times, such as ExecStart, clear it first with an empty line:

[Service]
ExecStart=
ExecStart=/usr/bin/my-wrapper

Files in /etc are on the root file system, which a full software update replaces, so install your units and drop-ins from your own Yocto layer for products; see Developing Applications and Kernel Modules.

Timers 

A .timer unit starts a service on a schedule, like cron. systemctl list-timers shows the timers and when each runs next:

root@imx93-cargt-00363-00428:~# systemctl list-timers --all
NEXT                            LEFT LAST                         PASSED UNIT                         ACTIVATES
Sat 2026-10-31 17:23:22 UTC 3h 16min Fri 2026-10-30 17:23:22 UTC 20h ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service

1 timers listed.

A minimal pair that runs a script every 15 minutes, starting 2 minutes after boot. The timer starts the service with the same name:

# /etc/systemd/system/my-report.service
[Unit]
Description=Send a status report

[Service]
Type=oneshot
ExecStart=/usr/bin/my-report.sh

# /etc/systemd/system/my-report.timer
[Unit]
Description=Send a status report every 15 minutes

[Timer]
OnBootSec=2min
OnUnitActiveSec=15min

[Install]
WantedBy=timers.target

Enable the timer, not the service:

systemctl daemon-reload
systemctl enable --now my-report.timer
systemctl list-timers my-report.timer

OnCalendar=*-*-* 02:00:00 runs at a fixed time of day instead. A timer that uses wall-clock time needs a correct clock; see Real-Time Clock.

System and User Services 

Most units are system units, run by systemd as process 1. systemd can also run a user manager per logged-in user, with that user’s own units, controlled with systemctl --user. Weston is the main example, and the platforms differ:

i.MX: Weston is a system service, weston.service, running as root:

root@imx93-cargt-00363-00428:~# systemctl status weston
● weston.service - Weston, a Wayland compositor, as a system service
     Loaded: loaded (/usr/lib/systemd/system/weston.service; enabled; preset: enabled)
     Active: active (running) since Fri 2026-10-30 17:08:27 UTC; 20h ago
...

Restart it with systemctl restart weston.

STM32MP2: the system service weston-graphical-session.service logs in the weston user and starts Weston as that user’s own weston.service. Restart the whole session with systemctl restart weston-graphical-session, or control Weston in the weston user’s manager from a root shell:
```
systemctl --user -M weston@ status weston
systemctl --user -M weston@ restart weston
```
This is how ST’s OpenSTLinux layers install Weston; these commands have not yet been tested on a Cargt STM32MP2 board.

The Main Cargt Services 

Unit	What it does
`weston.service`	The Wayland compositor (a user unit on STM32MP2; see above)
`nxp-wifi.service`	Loads the Wi-Fi driver at boot (i.MX); see Wi-Fi
`nxp-bluetooth.service`	Brings up Bluetooth after Wi-Fi; see Bluetooth
`NetworkManager.service`	Ethernet, Wi-Fi and cellular; see Networking with NetworkManager
`swupdate.service`, `swupdate-progress.service`	SWUpdate and its web interface, and the reboot after an update (i.MX); see Software Updates
`grow-data-part.service`	Grows and mounts `/data` at boot (i.MX); see Storage and Boot

On STM32MP2, rauc status shows the update state; see RAUC A/B OTA Updates — STM32MP2 (00395-01-00365 / 00395-02-00365).

systemd Services and Timers

Running Now vs. Starting at Boot

Finding Problems

Turning a Service Off Completely

Looking at and Changing a Unit

Timers

System and User Services

The Main Cargt Services