Stefan: Argent SystemD management of services

2026-09-25T20:55:57Z

Argent SystemD management of services

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=== Systemd on Argent ===

Argent runs on '''systemd''', the Gentoo profile is <code>default/linux/amd64/23.0/desktop/plasma/systemd</code>. There is no OpenRC: our make.conf disables the <code>openrc</code> and <code>sysvinit</code> USE flags, and <code>/etc/init.d</code> is not even installed (<code>INSTALL_MASK</code>).

So everything the Gentoo and systemd documentation says applies to Argent too:

* [https://wiki.gentoo.org/wiki/Systemd Gentoo wiki: systemd]
* the man pages that come with systemd, on your system: <code>man systemctl</code>, <code>man journalctl</code>, <code>man systemd.unit</code>, <code>man systemd.service</code>, <code>man systemd.timer</code>

The tools you will use, all part of systemd:

* <code>systemctl</code>: start, stop, enable, disable and look at services
* <code>journalctl</code>: read the logs
* <code>systemd-analyze</code>: boot time, and what slows it down
* <code>coredumpctl</code>: programs that crashed
* <code>timedatectl</code>, <code>hostnamectl</code>, <code>localectl</code>, <code>resolvectl</code>, <code>loginctl</code>: time, hostname, keyboard and language, DNS, sessions

This page explains what Argent runs, and how you manage it.

== What runs on a fresh Argent ==

=== System services ===

These are enabled on an installed Argent:

{| class="wikitable"
! Service !! What it does !! Package
|-
| <code>sddm.service</code> || the login screen, also known as <code>display-manager.service</code> || <code>x11-misc/sddm</code>
|-
| <code>NetworkManager.service</code> || the network (wired, wireless, VPN) || <code>net-misc/networkmanager</code>
|-
| <code>NetworkManager-dispatcher.service</code> || runs scripts when the network changes || <code>net-misc/networkmanager</code>
|-
| <code>NetworkManager-wait-online.service</code> || makes <code>network-online.target</code> wait for the network || <code>net-misc/networkmanager</code>
|-
| <code>ModemManager.service</code> || mobile broadband modems || <code>net-misc/modemmanager</code>
|-
| <code>systemd-resolved.service</code> || DNS, <code>/etc/resolv.conf</code> points to it || <code>sys-apps/systemd</code>
|-
| <code>avahi-daemon.service</code> and <code>.socket</code> || finds printers and other machines on your network (mDNS) || <code>net-dns/avahi</code>
|-
| <code>cups.service</code>, <code>.socket</code> and <code>.path</code> || printing || <code>net-print/cups</code>
|-
| <code>lvm2-monitor.service</code> || LVM monitoring || <code>sys-fs/lvm2</code>
|-
| <code>argent-config-vbox.service</code> || loads the VirtualBox video driver before the login screen || <code>app-misc/argent-config-files</code>
|-
| <code>virtualbox-guest-additions.service</code> || VirtualBox guest tools, it starts '''only''' inside VirtualBox || <code>app-emulation/virtualbox-guest-additions</code>
|-
| <code>getty@tty1.service</code> || the text console on tty1 || <code>sys-apps/systemd</code>
|}

The default target is <code>graphical.target</code>, so Argent boots straight to the login screen.

Some services are not enabled, but still run: they are started on demand, by D-Bus, when a program asks for them. For example <code>polkit</code>, <code>udisks2</code> (disks), <code>upower</code> (battery) and <code>power-profiles-daemon</code> (power profiles). Leave them alone.

=== User services ===

Every user who logs in gets their own systemd, with their own services. On Argent:

* the sound: <code>pipewire.service</code>, <code>pipewire-pulse.service</code> and <code>wireplumber.service</code>, enabled for each user. PipeWire replaces PulseAudio
* the whole Plasma desktop runs as user services: <code>plasma-plasmashell.service</code>, <code>plasma-kwin_wayland.service</code>, <code>plasma-powerdevil.service</code> and so on

To see them, as your user (not root):

<code>systemctl --user list-units --type=service</code>

=== Timers ===

Argent has no cron daemon, systemd timers do that job. Out of the box there is only <code>systemd-tmpfiles-clean.timer</code>, which cleans temporary files daily. To see all of them:

<code>systemctl list-timers --all</code>

=== Argent's own services ===

* <code>argent-config-vbox.service</code>, from <code>app-misc/argent-config-files</code>: runs <code>modprobe vboxvideo</code> before <code>sddm</code>, so the login screen works in VirtualBox
* <code>argentlive.service</code>: only on the live ISO, it prepares the live session. It is not installed on your system

The live ISO also enables <code>connman</code>, <code>dkms</code>, <code>dm-event</code> and <code>lvm2-lvmetad</code> when they are there, see the avasile page (<code>--makeiso</code>).

== Managing services ==

Everything below needs root, except the <code>--user</code> commands, which you run as your own user.

To see how a service is doing, with its last log lines:

<code>systemctl status NetworkManager</code>

To start, stop or restart it now:

<code>systemctl start cups</code>

<code>systemctl stop cups</code>

<code>systemctl restart cups</code>

To start it at every boot (<code>enable</code>), or not anymore (<code>disable</code>). <code>--now</code> also starts or stops it right away:

<code>systemctl enable --now sshd</code>

<code>systemctl disable --now sshd</code>

To make sure a service '''never''' starts, not even when something else asks for it:

<code>systemctl mask ModemManager</code>

<code>systemctl unmask ModemManager</code>

To see what is enabled, and what failed:

<code>systemctl list-unit-files --state=enabled</code>

<code>systemctl --failed</code>

For your own user services, add <code>--user</code>, as your user:

<code>systemctl --user restart pipewire</code>

=== Installing a package with a service ===

'''On Gentoo, and so on Argent, installing a package never enables its service.''' That's why <code>systemctl status</code> shows <code>preset: disabled</code> next to almost everything. You install, then you enable:

<code>epkg install net-misc/openssh</code>

<code>systemctl enable --now sshd</code>

The same when you remove a package: disable its service first.

<code>systemctl disable --now sshd</code>

<code>epkg remove net-misc/openssh</code>

=== Time synchronization ===

Argent doesn't enable time synchronization by default. <code>timedatectl</code> shows you if your clock is synced:

<code>timedatectl</code>

To turn it on (it uses <code>systemd-timesyncd</code>, already installed with systemd):

<code>timedatectl set-ntp true</code>

== Logs ==

The logs are kept by <code>systemd-journald</code>, in <code>/var/log/journal</code>, so they survive a reboot.

The logs of one service:

<code>journalctl -u NetworkManager</code>

Follow them live:

<code>journalctl -u NetworkManager -f</code>

Everything since the last boot, or from the boot before:

<code>journalctl -b</code>

<code>journalctl -b -1</code>

Only the errors since the last boot:

<code>journalctl -b -p err</code>

How much space the logs take, and how to shrink them:

<code>journalctl --disk-usage</code>

<code>journalctl --vacuum-size=200M</code>

== Where the unit files live ==

{| class="wikitable"
! Directory !! What is there !! Yours?
|-
| <code>/usr/lib/systemd/system/</code> || system services installed by packages || '''no''', overwritten at every upgrade
|-
| <code>/etc/systemd/system/</code> || the enable links, your overrides, your own services || yes
|-
| <code>/usr/lib/systemd/user/</code> || user services installed by packages || '''no'''
|-
| <code>/etc/systemd/user/</code> || user services for all users || yes
|-
| <code>~/.config/systemd/user/</code> || user services only for you || yes
|}

What is in <code>/etc</code> wins over what is in <code>/usr/lib</code>. So '''never edit a file in <code>/usr/lib/systemd</code>''', the next <code>epkg upgrade</code> puts it back. Override it in <code>/etc</code> instead.

After you change any unit file by hand, tell systemd:

<code>systemctl daemon-reload</code>

== Changing an installed service ==

<code>systemctl edit</code> opens an editor with an empty override (a "drop-in"). You write only what you want to change, and it is saved in <code>/etc/systemd/system/<service>.d/override.conf</code>, so it survives upgrades:

<code>systemctl edit cups</code>

For example, to restart cups whenever it crashes:

<pre>
[Service]
Restart=on-failure
RestartSec=5s
</pre>

To see the service together with your changes:

<code>systemctl cat cups</code>

To throw your changes away and go back to the package's version:

<code>systemctl revert cups</code>

== Adding your own service ==

Say you have a script, <code>/usr/local/bin/my-backup.sh</code>, that you want systemd to run. Create <code>/etc/systemd/system/my-backup.service</code>:

<pre>
[Unit]
Description=My backup
After=network-online.target
Wants=network-online.target

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

[Install]
WantedBy=multi-user.target
</pre>

Then:

<code>systemctl daemon-reload</code>

<code>systemctl enable --now my-backup.service</code>

For something that keeps running (a server, a daemon), use <code>Type=simple</code> and add <code>Restart=on-failure</code>. <code>man systemd.service</code> has all the options.

=== Running it on a schedule ===

Instead of cron, a timer with the same name as the service. Create <code>/etc/systemd/system/my-backup.timer</code>:

<pre>
[Unit]
Description=My backup, every night

[Timer]
OnCalendar=*-*-* 02:00:00
Persistent=true

[Install]
WantedBy=timers.target
</pre>

<code>Persistent=true</code> means that if the machine was off at 02:00, the backup runs at the next boot. Then enable the timer, '''not''' the service:

<code>systemctl daemon-reload</code>

<code>systemctl disable my-backup.service</code>

<code>systemctl enable --now my-backup.timer</code>

<code>systemctl list-timers</code>

=== A service for your user only ===

The same, but in <code>~/.config/systemd/user/</code>, with <code>WantedBy=default.target</code>, and with <code>--user</code>, as your user:

<code>systemctl --user daemon-reload</code>

<code>systemctl --user enable --now my-sync.service</code>

It starts when you log in, and stops when you log out.

== Configuring systemd itself ==

systemd's own settings are in <code>/etc/systemd/</code>: <code>journald.conf</code>, <code>logind.conf</code>, <code>resolved.conf</code>, <code>system.conf</code>, <code>sleep.conf</code>, ... On Argent they are all left at the systemd defaults.

Don't edit those files, add a drop-in next to them. For example, to keep the logs under 500 MB, create <code>/etc/systemd/journald.conf.d/100-my.conf</code>:

<pre>
[Journal]
SystemMaxUse=500M
</pre>

<code>systemctl restart systemd-journald</code>

Every file has its man page: <code>man journald.conf</code>, <code>man logind.conf</code>, <code>man resolved.conf</code>, ...

== When something goes wrong ==

What failed:

<code>systemctl --failed</code>

Why it failed:

<code>systemctl status <service></code>

<code>journalctl -u <service> -b</code>

What crashed:

<code>coredumpctl list</code>

<code>coredumpctl info <PID></code>

Why the boot is slow:

<code>systemd-analyze</code>

<code>systemd-analyze blame</code>

<code>systemd-analyze critical-chain</code>

If you ask for help on our channels, bring the output of <code>systemctl --failed</code> and <code>journalctl -b -p err</code>.

Argent SystemD Services - Revision history

Stefan: Argent SystemD management of services