</refsect1>
<refsect1>
- <title>Special System Units</title>
-
- <variablelist>
- <varlistentry>
- <term><filename>-.mount</filename></term>
- <listitem>
- <para>The root mount point, i.e. the mount unit for the <filename>/</filename> path. This unit is
- unconditionally active, during the entire time the system is up, as this mount point is where the basic
- userspace is running from.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>basic.target</filename></term>
- <listitem>
- <para>A special target unit covering basic boot-up.</para>
-
- <para>systemd automatically adds dependency of the type
- <varname>After=</varname> for this target unit to all
- services (except for those with
- <varname>DefaultDependencies=no</varname>).</para>
-
- <para>Usually, this should pull-in all local mount points plus
- <filename>/var</filename>, <filename>/tmp</filename> and
- <filename>/var/tmp</filename>, swap devices, sockets, timers,
- path units and other basic initialization necessary for general
- purpose daemons. The mentioned mount points are special cased
- to allow them to be remote.
- </para>
-
- <para>This target usually does not pull in any non-target units
- directly, but rather does so indirectly via other early boot targets.
- It is instead meant as a synchronization point for late boot
- services. Refer to
- <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
- for details on the targets involved.
- </para>
-
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>ctrl-alt-del.target</filename></term>
- <listitem>
- <para>systemd starts this target whenever Control+Alt+Del is
- pressed on the console. Usually, this should be aliased
- (symlinked) to <filename>reboot.target</filename>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>cryptsetup.target</filename></term>
- <listitem>
- <para>A target that pulls in setup services for all
- encrypted block devices.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>dbus.service</filename></term>
- <listitem>
- <para>A special unit for the D-Bus bus daemon. As soon as
- this service is fully started up systemd will connect to it
- and register its service.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>dbus.socket</filename></term>
- <listitem>
- <para>A special unit for the D-Bus system bus socket. All
- units with <varname>Type=dbus</varname> automatically gain a
- dependency on this unit.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>default.target</filename></term>
- <listitem>
- <para>The default unit systemd starts at bootup. Usually,
- this should be aliased (symlinked) to
- <filename>multi-user.target</filename> or
- <filename>graphical.target</filename>.</para>
-
- <para>The default unit systemd starts at bootup can be
- overridden with the <varname>systemd.unit=</varname> kernel
- command line option.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>display-manager.service</filename></term>
- <listitem>
- <para>The display manager service. Usually, this should be
- aliased (symlinked) to <filename>gdm.service</filename> or a
- similar display manager service.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>emergency.target</filename></term>
- <listitem>
- <para>A special target unit that starts an emergency shell on the main console. This target does not pull in
- any services or mounts. It is the most minimal version of starting the system in order to acquire an
- interactive shell; the only processes running are usually just the system manager (PID 1) and the shell
- process. This unit is supposed to be used with the kernel command line option
- <varname>systemd.unit=</varname>; it is also used when a file system check on a required file system fails,
- and boot-up cannot continue. Compare with <filename>rescue.target</filename>, which serves a similar purpose,
- but also starts the most basic services and mounts all file systems.</para>
-
- <para>Use the <literal>systemd.unit=emergency.target</literal> kernel command line option to boot into this
- mode. A short alias for this kernel command line option is <literal>emergency</literal>, for compatibility
- with SysV.</para>
-
- <para>In many ways booting into <filename>emergency.target</filename> is similar to the effect of booting
- with <literal>init=/bin/sh</literal> on the kernel command line, except that emergency mode provides you with
- the full system and service manager, and allows starting individual units in order to continue the boot
- process in steps.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>exit.target</filename></term>
- <listitem>
- <para>A special service unit for shutting down the system or
- user service manager. It is equivalent to
- <filename>poweroff.target</filename> on non-container
- systems, and also works in containers.</para>
-
- <para>systemd will start this unit when it receives the
- <constant>SIGTERM</constant> or <constant>SIGINT</constant>
- signal when running as user service daemon.</para>
-
- <para>Normally, this (indirectly) pulls in
- <filename>shutdown.target</filename>, which in turn should be
- conflicted by all units that want to be scheduled for
- shutdown when the service manager starts to exit.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>final.target</filename></term>
- <listitem>
- <para>A special target unit that is used during the shutdown
- logic and may be used to pull in late services after all
- normal services are already terminated and all mounts
- unmounted.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>getty.target</filename></term>
- <listitem>
- <para>A special target unit that pulls in statically
- configured local TTY <filename>getty</filename> instances.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>graphical.target</filename></term>
- <listitem>
- <para>A special target unit for setting up a graphical login
- screen. This pulls in
- <filename>multi-user.target</filename>.</para>
-
- <para>Units that are needed for graphical logins shall add
- <varname>Wants=</varname> dependencies for their unit to
- this unit (or <filename>multi-user.target</filename>) during
- installation. This is best configured via
- <varname>WantedBy=graphical.target</varname> in the unit's
- <literal>[Install]</literal> section.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>hibernate.target</filename></term>
- <listitem>
- <para>A special target unit for hibernating the system. This
- pulls in <filename>sleep.target</filename>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>hybrid-sleep.target</filename></term>
- <listitem>
- <para>A special target unit for hibernating and suspending
- the system at the same time. This pulls in
- <filename>sleep.target</filename>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>suspend-then-hibernate.target</filename></term>
- <listitem>
- <para>A special target unit for suspending the system for a period
- of time, waking it and putting it into hibernate. This pulls in
- <filename>sleep.target</filename>.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>halt.target</filename></term>
- <listitem>
- <para>A special target unit for shutting down and halting
- the system. Note that this target is distinct from
- <filename>poweroff.target</filename> in that it generally
- really just halts the system rather than powering it
- down.</para>
-
- <para>Applications wanting to halt the system should not start this unit
- directly, but should instead execute <command>systemctl halt</command>
- (possibly with the <option>--no-block</option> option) or call
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
- <command>org.freedesktop.systemd1.Manager.Halt</command> D-Bus method
- directly.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>init.scope</filename></term>
- <listitem>
- <para>This scope unit is where the system and service manager (PID 1) itself resides. It is active as long as
- the system is running.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>initrd-fs.target</filename></term>
- <listitem>
- <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- automatically adds dependencies of type
- <varname>Before=</varname> to
- <filename>sysroot-usr.mount</filename> and all mount points
- found in <filename>/etc/fstab</filename> that have
- <option>x-initrd.mount</option> and not have
- <option>noauto</option> mount options set.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>initrd-root-device.target</filename></term>
- <listitem>
- <para>A special initrd target unit that is reached when the root filesystem device is available, but before
- it has been mounted.
- <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- and
- <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- automatically setup the appropriate dependencies to make this happen.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>initrd-root-fs.target</filename></term>
- <listitem>
- <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- automatically adds dependencies of type
- <varname>Before=</varname> to the
- <filename>sysroot.mount</filename> unit, which is generated
- from the kernel command line.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>kbrequest.target</filename></term>
- <listitem>
- <para>systemd starts this target whenever Alt+ArrowUp is
- pressed on the console. Note that any user with physical access
- to the machine will be able to do this, without authentication,
- so this should be used carefully.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>kexec.target</filename></term>
- <listitem>
- <para>A special target unit for shutting down and rebooting
- the system via kexec.</para>
-
- <para>Applications wanting to reboot the system should not start this unit
- directly, but should instead execute <command>systemctl kexec</command>
- (possibly with the <option>--no-block</option> option) or call
- <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
- <command>org.freedesktop.systemd1.Manager.KExec</command> D-Bus method
- directly.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>local-fs.target</filename></term>
- <listitem>
- <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- automatically adds dependencies of type
- <varname>Before=</varname> to all mount units that refer to
- local mount points for this target unit. In addition, it
- adds dependencies of type <varname>Wants=</varname> to this
- target unit for those mounts listed in
- <filename>/etc/fstab</filename> that have the
- <option>auto</option> mount option set.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>machines.target</filename></term>
- <listitem>
- <para>A standard target unit for starting all the containers
- and other virtual machines. See <filename>systemd-nspawn@.service</filename>
- for an example.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>multi-user.target</filename></term>
- <listitem>
- <para>A special target unit for setting up a multi-user
- system (non-graphical). This is pulled in by
- <filename>graphical.target</filename>.</para>
-
- <para>Units that are needed for a multi-user system shall
- add <varname>Wants=</varname> dependencies for their unit to
- this unit during installation. This is best configured via
- <varname>WantedBy=multi-user.target</varname> in the unit's
- <literal>[Install]</literal> section.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>network-online.target</filename></term>
- <listitem>
- <para>Units that strictly require a configured network
- connection should pull in
- <filename>network-online.target</filename> (via a
- <varname>Wants=</varname> type dependency) and order
- themselves after it. This target unit is intended to pull in
- a service that delays further execution until the network is
- sufficiently set up. What precisely this requires is left to
- the implementation of the network managing service.</para>
-
- <para>Note the distinction between this unit and
- <filename>network.target</filename>. This unit is an active
- unit (i.e. pulled in by the consumer rather than the
- provider of this functionality) and pulls in a service which
- possibly adds substantial delays to further execution. In
- contrast, <filename>network.target</filename> is a passive
- unit (i.e. pulled in by the provider of the functionality,
- rather than the consumer) that usually does not delay
- execution much. Usually, <filename>network.target</filename>
- is part of the boot of most systems, while
- <filename>network-online.target</filename> is not, except
- when at least one unit requires it. Also see <ulink
- url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
- Services After the Network is up</ulink> for more
- information.</para>
-
- <para>All mount units for remote network file systems
- automatically pull in this unit, and order themselves after
- it. Note that networking daemons that simply provide
- functionality to other hosts generally do not need to pull
- this in.</para>
-
- <para>systemd automatically adds dependencies of type <varname>Wants=</varname> and <varname>After=</varname>
- for this target unit to all SysV init script service units with an LSB header referring to the
- <literal>$network</literal> facility.</para>
-
- <para>Note that this unit is only useful during the original system start-up logic. After the system has
- completed booting up, it will not track the online state of the system anymore. Due to this it cannot be used
- as a network connection monitor concept, it is purely a one-time system start-up concept.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>paths.target</filename></term>
- <listitem>
- <para>A special target unit that sets up all path units (see
- <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details) that shall be active after boot.</para>
-
- <para>It is recommended that path units installed by
- applications get pulled in via <varname>Wants=</varname>
- dependencies from this unit. This is best configured via a
- <varname>WantedBy=paths.target</varname> in the path unit's
- <literal>[Install]</literal> section.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>poweroff.target</filename></term>
- <listitem>
- <para>A special target unit for shutting down and powering
- off the system.</para>
-
- <para>Applications wanting to power off the system should not start this unit
- directly, but should instead execute <command>systemctl poweroff</command>
- (possibly with the <option>--no-block</option> option) or call
- <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
- <command>org.freedesktop.login1.Manager.PowerOff</command> D-Bus method
- directly.</para>
-
- <para><filename>runlevel0.target</filename> is an alias for
- this target unit, for compatibility with SysV.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>reboot.target</filename></term>
- <listitem>
- <para>A special target unit for shutting down and rebooting
- the system.</para>
-
- <para>Applications wanting to reboot the system should not start this unit
- directly, but should instead execute <command>systemctl reboot</command>
- (possibly with the <option>--no-block</option> option) or call
- <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
- <command>org.freedesktop.login1.Manager.Reboot</command> D-Bus method
- directly.</para>
-
- <para><filename>runlevel6.target</filename> is an alias for
- this target unit, for compatibility with SysV.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>remote-cryptsetup.target</filename></term>
- <listitem>
- <para>Similar to <filename>cryptsetup.target</filename>, but for encrypted
- devices which are accessed over the network. It is used for
- <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- entries marked with <option>_netdev</option>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>remote-fs.target</filename></term>
- <listitem>
- <para>Similar to <filename>local-fs.target</filename>, but
- for remote mount points.</para>
-
- <para>systemd automatically adds dependencies of type
- <varname>After=</varname> for this target unit to all SysV
- init script service units with an LSB header referring to
- the <literal>$remote_fs</literal> facility.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>rescue.target</filename></term>
- <listitem>
- <para>A special target unit that pulls in the base system (including system mounts) and spawns a rescue
- shell. Isolate to this target in order to administer the system in single-user mode with all file systems
- mounted but with no services running, except for the most basic. Compare with
- <filename>emergency.target</filename>, which is much more reduced and does not provide the file systems or
- most basic services. Compare with <filename>multi-user.target</filename>, this target could be seen as
- <filename>single-user.target</filename>.</para>
-
- <para><filename>runlevel1.target</filename> is an alias for this target unit, for compatibility with
- SysV.</para>
-
- <para>Use the <literal>systemd.unit=rescue.target</literal> kernel command line option to boot into this
- mode. A short alias for this kernel command line option is <literal>1</literal>, for compatibility with
- SysV.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>runlevel2.target</filename></term>
- <term><filename>runlevel3.target</filename></term>
- <term><filename>runlevel4.target</filename></term>
- <term><filename>runlevel5.target</filename></term>
- <listitem>
- <para>These are targets that are called whenever the SysV
- compatibility code asks for runlevel 2, 3, 4, 5,
- respectively. It is a good idea to make this an alias for
- (i.e. symlink to) <filename>graphical.target</filename>
- (for runlevel 5) or <filename>multi-user.target</filename>
- (the others).</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>shutdown.target</filename></term>
- <listitem>
- <para>A special target unit that terminates the services on
- system shutdown.</para>
-
- <para>Services that shall be terminated on system shutdown
- shall add <varname>Conflicts=</varname> and
- <varname>Before=</varname> dependencies to this unit for
- their service unit, which is implicitly done when
- <varname>DefaultDependencies=yes</varname> is set (the
- default).</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>sigpwr.target</filename></term>
- <listitem>
- <para>A special target that is started when systemd receives
- the SIGPWR process signal, which is normally sent by the
- kernel or UPS daemons when power fails.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>sleep.target</filename></term>
- <listitem>
- <para>A special target unit that is pulled in by
- <filename>suspend.target</filename>,
- <filename>hibernate.target</filename> and
- <filename>hybrid-sleep.target</filename> and may be used to
- hook units into the sleep state logic.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>slices.target</filename></term>
- <listitem>
- <para>A special target unit that sets up all slice units (see
- <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
- details) that shall be active after boot. By default the generic <filename>system.slice</filename>
- slice unit, as well as the root slice unit <filename>-.slice</filename>, is pulled in and ordered before
- this unit (see below).</para>
-
- <para>It's a good idea to add <varname>WantedBy=slices.target</varname> lines to the <literal>[Install]</literal>
- section of all slices units that may be installed dynamically.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>sockets.target</filename></term>
- <listitem>
- <para>A special target unit that sets up all socket
- units (see
- <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details) that shall be active after boot.</para>
-
- <para>Services that can be socket-activated shall add
- <varname>Wants=</varname> dependencies to this unit for
- their socket unit during installation. This is best
- configured via a <varname>WantedBy=sockets.target</varname>
- in the socket unit's <literal>[Install]</literal>
- section.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>suspend.target</filename></term>
- <listitem>
- <para>A special target unit for suspending the system. This
- pulls in <filename>sleep.target</filename>.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>swap.target</filename></term>
- <listitem>
- <para>Similar to <filename>local-fs.target</filename>, but
- for swap partitions and swap files.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>sysinit.target</filename></term>
- <listitem>
- <para>systemd automatically adds dependencies of the types
- <varname>Requires=</varname> and <varname>After=</varname>
- for this target unit to all services (except for those with
- <varname>DefaultDependencies=no</varname>).</para>
-
- <para>This target pulls in the services required for system
- initialization. System services pulled in by this target should
- declare <varname>DefaultDependencies=no</varname> and specify
- all their dependencies manually, including access to anything
- more than a read only root filesystem. For details on the
- dependencies of this target, refer to
- <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>syslog.socket</filename></term>
- <listitem>
- <para>The socket unit syslog implementations should listen
- on. All userspace log messages will be made available on
- this socket. For more information about syslog integration,
- please consult the <ulink
- url="https://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
- Interface</ulink> document.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>system-update.target</filename></term>
- <term><filename>system-update-pre.target</filename></term>
- <term><filename>system-update-cleanup.service</filename></term>
- <listitem>
- <para>A special target unit that is used for offline system updates.
- <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
- will redirect the boot process to this target if <filename>/system-update</filename>
- exists. For more information see
- <citerefentry><refentrytitle>systemd.offline-updates</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
- </para>
-
- <para>Updates should happen before the <filename>system-update.target</filename> is reached, and the services
- which implement them should cause the machine to reboot. The main units executing the update should order
- themselves after <filename>system-update-pre.target</filename> but not pull it in. Services which want to run
- during system updates only, but before the actual system update is executed should order themselves before
- this unit and pull it in. As a safety measure, if this does not happen, and
- <filename>/system-update</filename> still exists after <filename>system-update.target</filename> is reached,
- <filename>system-update-cleanup.service</filename> will remove this symlink and reboot the machine.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>timers.target</filename></term>
- <listitem>
- <para>A special target unit that sets up all timer units
- (see
- <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details) that shall be active after boot.</para>
-
- <para>It is recommended that timer units installed by
- applications get pulled in via <varname>Wants=</varname>
- dependencies from this unit. This is best configured via
- <varname>WantedBy=timers.target</varname> in the timer
- unit's <literal>[Install]</literal> section.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>umount.target</filename></term>
- <listitem>
- <para>A special target unit that unmounts all mount and
- automount points on system shutdown.</para>
-
- <para>Mounts that shall be unmounted on system shutdown
- shall add Conflicts dependencies to this unit for their
- mount unit, which is implicitly done when
- <varname>DefaultDependencies=yes</varname> is set (the
- default).</para>
- </listitem>
- </varlistentry>
-
- </variablelist>
- </refsect1>
+ <title>Units managed by the system's service manager</title>
+
+ <refsect2>
+ <title>Special System Units</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>-.mount</filename></term>
+ <listitem>
+ <para>The root mount point, i.e. the mount unit for the <filename>/</filename>
+ path. This unit is unconditionally active, during the entire time the system is up, as
+ this mount point is where the basic userspace is running from.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>basic.target</filename></term>
+ <listitem>
+ <para>A special target unit covering basic boot-up.</para>
+
+ <para>systemd automatically adds dependency of the type
+ <varname>After=</varname> for this target unit to all
+ services (except for those with
+ <varname>DefaultDependencies=no</varname>).</para>
+
+ <para>Usually, this should pull-in all local mount points plus
+ <filename>/var</filename>, <filename>/tmp</filename> and
+ <filename>/var/tmp</filename>, swap devices, sockets, timers,
+ path units and other basic initialization necessary for general
+ purpose daemons. The mentioned mount points are special cased
+ to allow them to be remote.
+ </para>
+
+ <para>This target usually does not pull in any non-target units
+ directly, but rather does so indirectly via other early boot targets.
+ It is instead meant as a synchronization point for late boot
+ services. Refer to
+ <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details on the targets involved.
+ </para>
- <refsect1>
- <title>Special System Units for Devices</title>
-
- <para>Some target units are automatically pulled in as devices of
- certain kinds show up in the system. These may be used to
- automatically activate various services based on the specific type
- of the available hardware.</para>
-
- <variablelist>
- <varlistentry>
- <term><filename>bluetooth.target</filename></term>
- <listitem>
- <para>This target is started automatically as soon as a
- Bluetooth controller is plugged in or becomes available at
- boot.</para>
-
- <para>This may be used to pull in Bluetooth management
- daemons dynamically when Bluetooth hardware is found.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>printer.target</filename></term>
- <listitem>
- <para>This target is started automatically as soon as a
- printer is plugged in or becomes available at boot.</para>
-
- <para>This may be used to pull in printer management daemons
- dynamically when printer hardware is found.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>smartcard.target</filename></term>
- <listitem>
- <para>This target is started automatically as soon as a
- smartcard controller is plugged in or becomes available at
- boot.</para>
-
- <para>This may be used to pull in smartcard management
- daemons dynamically when smartcard hardware is found.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>sound.target</filename></term>
- <listitem>
- <para>This target is started automatically as soon as a
- sound card is plugged in or becomes available at
- boot.</para>
-
- <para>This may be used to pull in audio management daemons
- dynamically when audio hardware is found.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>ctrl-alt-del.target</filename></term>
+ <listitem>
+ <para>systemd starts this target whenever Control+Alt+Del is
+ pressed on the console. Usually, this should be aliased
+ (symlinked) to <filename>reboot.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>cryptsetup.target</filename></term>
+ <listitem>
+ <para>A target that pulls in setup services for all
+ encrypted block devices.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>dbus.service</filename></term>
+ <listitem>
+ <para>A special unit for the D-Bus bus daemon. As soon as
+ this service is fully started up systemd will connect to it
+ and register its service.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>dbus.socket</filename></term>
+ <listitem>
+ <para>A special unit for the D-Bus system bus socket. All
+ units with <varname>Type=dbus</varname> automatically gain a
+ dependency on this unit.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>default.target</filename></term>
+ <listitem>
+ <para>The default unit systemd starts at bootup. Usually,
+ this should be aliased (symlinked) to
+ <filename>multi-user.target</filename> or
+ <filename>graphical.target</filename>.</para>
+
+ <para>The default unit systemd starts at bootup can be
+ overridden with the <varname>systemd.unit=</varname> kernel
+ command line option.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>display-manager.service</filename></term>
+ <listitem>
+ <para>The display manager service. Usually, this should be
+ aliased (symlinked) to <filename>gdm.service</filename> or a
+ similar display manager service.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>emergency.target</filename></term>
+ <listitem>
+ <para>A special target unit that starts an emergency shell on the main console. This
+ target does not pull in any services or mounts. It is the most minimal version of
+ starting the system in order to acquire an interactive shell; the only processes running
+ are usually just the system manager (PID 1) and the shell process. This unit is supposed
+ to be used with the kernel command line option <varname>systemd.unit=</varname>; it is
+ also used when a file system check on a required file system fails, and boot-up cannot
+ continue. Compare with <filename>rescue.target</filename>, which serves a similar
+ purpose, but also starts the most basic services and mounts all file systems.</para>
+
+ <para>Use the <literal>systemd.unit=emergency.target</literal> kernel command line
+ option to boot into this mode. A short alias for this kernel command line option is
+ <literal>emergency</literal>, for compatibility with SysV.</para>
+
+ <para>In many ways booting into <filename>emergency.target</filename> is similar to the
+ effect of booting with <literal>init=/bin/sh</literal> on the kernel command line,
+ except that emergency mode provides you with the full system and service manager, and
+ allows starting individual units in order to continue the boot process in steps.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>exit.target</filename></term>
+ <listitem>
+ <para>A special service unit for shutting down the system or
+ user service manager. It is equivalent to
+ <filename>poweroff.target</filename> on non-container
+ systems, and also works in containers.</para>
+
+ <para>systemd will start this unit when it receives the
+ <constant>SIGTERM</constant> or <constant>SIGINT</constant>
+ signal when running as user service daemon.</para>
+
+ <para>Normally, this (indirectly) pulls in
+ <filename>shutdown.target</filename>, which in turn should be
+ conflicted by all units that want to be scheduled for
+ shutdown when the service manager starts to exit.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>final.target</filename></term>
+ <listitem>
+ <para>A special target unit that is used during the shutdown
+ logic and may be used to pull in late services after all
+ normal services are already terminated and all mounts
+ unmounted.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>getty.target</filename></term>
+ <listitem>
+ <para>A special target unit that pulls in statically
+ configured local TTY <filename>getty</filename> instances.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>graphical.target</filename></term>
+ <listitem>
+ <para>A special target unit for setting up a graphical login
+ screen. This pulls in
+ <filename>multi-user.target</filename>.</para>
+
+ <para>Units that are needed for graphical logins shall add
+ <varname>Wants=</varname> dependencies for their unit to
+ this unit (or <filename>multi-user.target</filename>) during
+ installation. This is best configured via
+ <varname>WantedBy=graphical.target</varname> in the unit's
+ <literal>[Install]</literal> section.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>hibernate.target</filename></term>
+ <listitem>
+ <para>A special target unit for hibernating the system. This
+ pulls in <filename>sleep.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>hybrid-sleep.target</filename></term>
+ <listitem>
+ <para>A special target unit for hibernating and suspending
+ the system at the same time. This pulls in
+ <filename>sleep.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>suspend-then-hibernate.target</filename></term>
+ <listitem>
+ <para>A special target unit for suspending the system for a period
+ of time, waking it and putting it into hibernate. This pulls in
+ <filename>sleep.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>halt.target</filename></term>
+ <listitem>
+ <para>A special target unit for shutting down and halting
+ the system. Note that this target is distinct from
+ <filename>poweroff.target</filename> in that it generally
+ really just halts the system rather than powering it
+ down.</para>
+
+ <para>Applications wanting to halt the system should not start this unit
+ directly, but should instead execute <command>systemctl halt</command>
+ (possibly with the <option>--no-block</option> option) or call
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>org.freedesktop.systemd1.Manager.Halt</command> D-Bus method
+ directly.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>init.scope</filename></term>
+ <listitem>
+ <para>This scope unit is where the system and service manager (PID 1) itself resides. It
+ is active as long as the system is running.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>initrd-fs.target</filename></term>
+ <listitem>
+ <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ automatically adds dependencies of type
+ <varname>Before=</varname> to
+ <filename>sysroot-usr.mount</filename> and all mount points
+ found in <filename>/etc/fstab</filename> that have
+ <option>x-initrd.mount</option> and not have
+ <option>noauto</option> mount options set.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>initrd-root-device.target</filename></term>
+ <listitem>
+ <para>A special initrd target unit that is reached when the root filesystem device is available, but before
+ it has been mounted.
+ <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ automatically setup the appropriate dependencies to make this happen.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>initrd-root-fs.target</filename></term>
+ <listitem>
+ <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ automatically adds dependencies of type
+ <varname>Before=</varname> to the
+ <filename>sysroot.mount</filename> unit, which is generated
+ from the kernel command line.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>kbrequest.target</filename></term>
+ <listitem>
+ <para>systemd starts this target whenever Alt+ArrowUp is
+ pressed on the console. Note that any user with physical access
+ to the machine will be able to do this, without authentication,
+ so this should be used carefully.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>kexec.target</filename></term>
+ <listitem>
+ <para>A special target unit for shutting down and rebooting
+ the system via kexec.</para>
+
+ <para>Applications wanting to reboot the system should not start this unit
+ directly, but should instead execute <command>systemctl kexec</command>
+ (possibly with the <option>--no-block</option> option) or call
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
+ <command>org.freedesktop.systemd1.Manager.KExec</command> D-Bus method
+ directly.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>local-fs.target</filename></term>
+ <listitem>
+ <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ automatically adds dependencies of type
+ <varname>Before=</varname> to all mount units that refer to
+ local mount points for this target unit. In addition, it
+ adds dependencies of type <varname>Wants=</varname> to this
+ target unit for those mounts listed in
+ <filename>/etc/fstab</filename> that have the
+ <option>auto</option> mount option set.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>machines.target</filename></term>
+ <listitem>
+ <para>A standard target unit for starting all the containers
+ and other virtual machines. See <filename>systemd-nspawn@.service</filename>
+ for an example.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>multi-user.target</filename></term>
+ <listitem>
+ <para>A special target unit for setting up a multi-user
+ system (non-graphical). This is pulled in by
+ <filename>graphical.target</filename>.</para>
+
+ <para>Units that are needed for a multi-user system shall
+ add <varname>Wants=</varname> dependencies for their unit to
+ this unit during installation. This is best configured via
+ <varname>WantedBy=multi-user.target</varname> in the unit's
+ <literal>[Install]</literal> section.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>network-online.target</filename></term>
+ <listitem>
+ <para>Units that strictly require a configured network
+ connection should pull in
+ <filename>network-online.target</filename> (via a
+ <varname>Wants=</varname> type dependency) and order
+ themselves after it. This target unit is intended to pull in
+ a service that delays further execution until the network is
+ sufficiently set up. What precisely this requires is left to
+ the implementation of the network managing service.</para>
+
+ <para>Note the distinction between this unit and
+ <filename>network.target</filename>. This unit is an active
+ unit (i.e. pulled in by the consumer rather than the
+ provider of this functionality) and pulls in a service which
+ possibly adds substantial delays to further execution. In
+ contrast, <filename>network.target</filename> is a passive
+ unit (i.e. pulled in by the provider of the functionality,
+ rather than the consumer) that usually does not delay
+ execution much. Usually, <filename>network.target</filename>
+ is part of the boot of most systems, while
+ <filename>network-online.target</filename> is not, except
+ when at least one unit requires it. Also see <ulink
+ url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
+ Services After the Network is up</ulink> for more
+ information.</para>
+
+ <para>All mount units for remote network file systems
+ automatically pull in this unit, and order themselves after
+ it. Note that networking daemons that simply provide
+ functionality to other hosts generally do not need to pull
+ this in.</para>
+
+ <para>systemd automatically adds dependencies of type <varname>Wants=</varname> and
+ <varname>After=</varname> for this target unit to all SysV init script service units
+ with an LSB header referring to the <literal>$network</literal> facility.</para>
+
+ <para>Note that this unit is only useful during the original system start-up
+ logic. After the system has completed booting up, it will not track the online state of
+ the system anymore. Due to this it cannot be used as a network connection monitor
+ concept, it is purely a one-time system start-up concept.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>paths.target</filename></term>
+ <listitem>
+ <para>A special target unit that sets up all path units (see
+ <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) that shall be active after boot.</para>
+
+ <para>It is recommended that path units installed by
+ applications get pulled in via <varname>Wants=</varname>
+ dependencies from this unit. This is best configured via a
+ <varname>WantedBy=paths.target</varname> in the path unit's
+ <literal>[Install]</literal> section.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>poweroff.target</filename></term>
+ <listitem>
+ <para>A special target unit for shutting down and powering
+ off the system.</para>
+
+ <para>Applications wanting to power off the system should not start this unit
+ directly, but should instead execute <command>systemctl poweroff</command>
+ (possibly with the <option>--no-block</option> option) or call
+ <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
+ <command>org.freedesktop.login1.Manager.PowerOff</command> D-Bus method
+ directly.</para>
+
+ <para><filename>runlevel0.target</filename> is an alias for
+ this target unit, for compatibility with SysV.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>reboot.target</filename></term>
+ <listitem>
+ <para>A special target unit for shutting down and rebooting
+ the system.</para>
+
+ <para>Applications wanting to reboot the system should not start this unit
+ directly, but should instead execute <command>systemctl reboot</command>
+ (possibly with the <option>--no-block</option> option) or call
+ <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
+ <command>org.freedesktop.login1.Manager.Reboot</command> D-Bus method
+ directly.</para>
+
+ <para><filename>runlevel6.target</filename> is an alias for
+ this target unit, for compatibility with SysV.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>remote-cryptsetup.target</filename></term>
+ <listitem>
+ <para>Similar to <filename>cryptsetup.target</filename>, but for encrypted
+ devices which are accessed over the network. It is used for
+ <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ entries marked with <option>_netdev</option>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>remote-fs.target</filename></term>
+ <listitem>
+ <para>Similar to <filename>local-fs.target</filename>, but
+ for remote mount points.</para>
+
+ <para>systemd automatically adds dependencies of type
+ <varname>After=</varname> for this target unit to all SysV
+ init script service units with an LSB header referring to
+ the <literal>$remote_fs</literal> facility.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>rescue.target</filename></term>
+ <listitem>
+ <para>A special target unit that pulls in the base system (including system mounts) and
+ spawns a rescue shell. Isolate to this target in order to administer the system in
+ single-user mode with all file systems mounted but with no services running, except for
+ the most basic. Compare with <filename>emergency.target</filename>, which is much more
+ reduced and does not provide the file systems or most basic services. Compare with
+ <filename>multi-user.target</filename>, this target could be seen as
+ <filename>single-user.target</filename>.</para>
+
+ <para><filename>runlevel1.target</filename> is an alias for this target unit, for
+ compatibility with SysV.</para>
+
+ <para>Use the <literal>systemd.unit=rescue.target</literal> kernel command line option
+ to boot into this mode. A short alias for this kernel command line option is
+ <literal>1</literal>, for compatibility with SysV.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>runlevel2.target</filename></term>
+ <term><filename>runlevel3.target</filename></term>
+ <term><filename>runlevel4.target</filename></term>
+ <term><filename>runlevel5.target</filename></term>
+ <listitem>
+ <para>These are targets that are called whenever the SysV
+ compatibility code asks for runlevel 2, 3, 4, 5,
+ respectively. It is a good idea to make this an alias for
+ (i.e. symlink to) <filename>graphical.target</filename>
+ (for runlevel 5) or <filename>multi-user.target</filename>
+ (the others).</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>shutdown.target</filename></term>
+ <listitem>
+ <para>A special target unit that terminates the services on
+ system shutdown.</para>
+
+ <para>Services that shall be terminated on system shutdown
+ shall add <varname>Conflicts=</varname> and
+ <varname>Before=</varname> dependencies to this unit for
+ their service unit, which is implicitly done when
+ <varname>DefaultDependencies=yes</varname> is set (the
+ default).</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>sigpwr.target</filename></term>
+ <listitem>
+ <para>A special target that is started when systemd receives
+ the SIGPWR process signal, which is normally sent by the
+ kernel or UPS daemons when power fails.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>sleep.target</filename></term>
+ <listitem>
+ <para>A special target unit that is pulled in by
+ <filename>suspend.target</filename>,
+ <filename>hibernate.target</filename> and
+ <filename>hybrid-sleep.target</filename> and may be used to
+ hook units into the sleep state logic.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>slices.target</filename></term>
+ <listitem>
+ <para>A special target unit that sets up all slice units (see
+ <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) that shall be active after boot. By default the generic
+ <filename>system.slice</filename> slice unit, as well as the root slice unit
+ <filename>-.slice</filename>, is pulled in and ordered before this unit (see
+ below).</para>
+
+ <para>It's a good idea to add <varname>WantedBy=slices.target</varname> lines to the
+ <literal>[Install]</literal> section of all slices units that may be installed
+ dynamically.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>sockets.target</filename></term>
+ <listitem>
+ <para>A special target unit that sets up all socket
+ units (see
+ <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) that shall be active after boot.</para>
+
+ <para>Services that can be socket-activated shall add
+ <varname>Wants=</varname> dependencies to this unit for
+ their socket unit during installation. This is best
+ configured via a <varname>WantedBy=sockets.target</varname>
+ in the socket unit's <literal>[Install]</literal>
+ section.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>suspend.target</filename></term>
+ <listitem>
+ <para>A special target unit for suspending the system. This
+ pulls in <filename>sleep.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>swap.target</filename></term>
+ <listitem>
+ <para>Similar to <filename>local-fs.target</filename>, but
+ for swap partitions and swap files.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>sysinit.target</filename></term>
+ <listitem>
+ <para>systemd automatically adds dependencies of the types
+ <varname>Requires=</varname> and <varname>After=</varname>
+ for this target unit to all services (except for those with
+ <varname>DefaultDependencies=no</varname>).</para>
+
+ <para>This target pulls in the services required for system
+ initialization. System services pulled in by this target should
+ declare <varname>DefaultDependencies=no</varname> and specify
+ all their dependencies manually, including access to anything
+ more than a read only root filesystem. For details on the
+ dependencies of this target, refer to
+ <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>syslog.socket</filename></term>
+ <listitem>
+ <para>The socket unit syslog implementations should listen
+ on. All userspace log messages will be made available on
+ this socket. For more information about syslog integration,
+ please consult the <ulink
+ url="https://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
+ Interface</ulink> document.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>system-update.target</filename></term>
+ <term><filename>system-update-pre.target</filename></term>
+ <term><filename>system-update-cleanup.service</filename></term>
+ <listitem>
+ <para>A special target unit that is used for offline system updates.
+ <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+ will redirect the boot process to this target if <filename>/system-update</filename>
+ exists. For more information see
+ <citerefentry><refentrytitle>systemd.offline-updates</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
+ </para>
+
+ <para>Updates should happen before the <filename>system-update.target</filename> is
+ reached, and the services which implement them should cause the machine to reboot. The
+ main units executing the update should order themselves after
+ <filename>system-update-pre.target</filename> but not pull it in. Services which want to
+ run during system updates only, but before the actual system update is executed should
+ order themselves before this unit and pull it in. As a safety measure, if this does not
+ happen, and <filename>/system-update</filename> still exists after
+ <filename>system-update.target</filename> is reached,
+ <filename>system-update-cleanup.service</filename> will remove this symlink and reboot
+ the machine.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>timers.target</filename></term>
+ <listitem>
+ <para>A special target unit that sets up all timer units
+ (see
+ <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details) that shall be active after boot.</para>
+
+ <para>It is recommended that timer units installed by
+ applications get pulled in via <varname>Wants=</varname>
+ dependencies from this unit. This is best configured via
+ <varname>WantedBy=timers.target</varname> in the timer
+ unit's <literal>[Install]</literal> section.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>umount.target</filename></term>
+ <listitem>
+ <para>A special target unit that unmounts all mount and
+ automount points on system shutdown.</para>
+
+ <para>Mounts that shall be unmounted on system shutdown
+ shall add Conflicts dependencies to this unit for their
+ mount unit, which is implicitly done when
+ <varname>DefaultDependencies=yes</varname> is set (the
+ default).</para>
+ </listitem>
+ </varlistentry>
- <refsect1>
- <title>Special Passive System Units </title>
-
- <para>A number of special system targets are defined that can be
- used to properly order boot-up of optional services. These targets
- are generally not part of the initial boot transaction, unless
- they are explicitly pulled in by one of the implementing services.
- Note specifically that these <emphasis>passive</emphasis> target
- units are generally not pulled in by the consumer of a service,
- but by the provider of the service. This means: a consuming
- service should order itself after these targets (as appropriate),
- but not pull it in. A providing service should order itself before
- these targets (as appropriate) and pull it in (via a
- <varname>Wants=</varname> type dependency).</para>
-
- <para>Note that these passive units cannot be started manually,
- i.e. <literal>systemctl start time-sync.target</literal> will fail
- with an error. They can only be pulled in by dependency. This is
- enforced since they exist for ordering purposes only and thus are
- not useful as only unit within a transaction.</para>
-
- <variablelist>
- <varlistentry>
- <term><filename>cryptsetup-pre.target</filename></term>
- <listitem>
- <para>This passive target unit may be pulled in by services
- that want to run before any encrypted block device is set
- up. All encrypted block devices are set up after this target
- has been reached. Since the shutdown order is implicitly the
- reverse start-up order between units, this target is
- particularly useful to ensure that a service is shut down
- only after all encrypted block devices are fully
- stopped.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>getty-pre.target</filename></term>
- <listitem>
- <para>A special passive target unit. Users of this target
- are expected to pull it in the boot transaction via
- a dependency (e.g. <varname>Wants=</varname>). Order your
- unit before this unit if you want to make use of the console
- just before <filename>getty</filename> is started.
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>local-fs-pre.target</filename></term>
- <listitem>
- <para>This target unit is
- automatically ordered before
- all local mount points marked
- with <option>auto</option>
- (see above). It can be used to
- execute certain units before
- all local mounts.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>network.target</filename></term>
- <listitem>
- <para>This unit is supposed to indicate when network
- functionality is available, but it is only very weakly
- defined what that is supposed to mean, with one exception:
- at shutdown, a unit that is ordered after
- <filename>network.target</filename> will be stopped before
- the network — to whatever level it might be set up then —
- is shut down. It is hence useful when writing service files
- that require network access on shutdown, which should order
- themselves after this target, but not pull it in. Also see
- <ulink url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
- Services After the Network is up</ulink> for more
- information. Also see
- <filename>network-online.target</filename> described
- above.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>network-pre.target</filename></term>
- <listitem>
- <para>This passive target unit may be pulled in by services
- that want to run before any network is set up, for example
- for the purpose of setting up a firewall. All network
- management software orders itself after this target, but
- does not pull it in.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>nss-lookup.target</filename></term>
- <listitem>
- <para>A target that should be used as synchronization point for all host/network name service lookups. Note
- that this is independent of UNIX user/group name lookups for which <filename>nss-user-lookup.target</filename>
- should be used. All services for which the availability of full host/network name resolution is essential
- should be ordered after this target, but not pull it in. systemd automatically adds dependencies of type
- <varname>After=</varname> for this target unit to all SysV init script service units with an LSB header
- referring to the <literal>$named</literal> facility.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>nss-user-lookup.target</filename></term>
- <listitem>
- <para>A target that should be used as synchronization point for all regular UNIX user/group name service
- lookups. Note that this is independent of host/network name lookups for which
- <filename>nss-lookup.target</filename> should be used. All services for which the availability of the full
- user/group database is essential should be ordered after this target, but not pull it in. All services which
- provide parts of the user/group database should be ordered before this target, and pull it in. Note that this
- unit is only relevant for regular users and groups — system users and groups are required to be resolvable
- during earliest boot already, and hence do not need any special ordering against this target.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>remote-fs-pre.target</filename></term>
- <listitem>
- <para>This target unit is automatically ordered before all
- mount point units (see above) and cryptsetup devices
- marked with the <option>_netdev</option>. It can be used to run
- certain units before remote encrypted devices and mounts are established.
- Note that this unit is generally not part of the initial
- transaction, unless the unit that wants to be ordered before
- all remote mounts pulls it in via a
- <varname>Wants=</varname> type dependency. If the unit wants
- to be pulled in by the first remote mount showing up, it
- should use <filename>network-online.target</filename> (see
- above).</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>rpcbind.target</filename></term>
- <listitem>
- <para>The portmapper/rpcbind pulls in this target and orders
- itself before it, to indicate its availability. systemd
- automatically adds dependencies of type
- <varname>After=</varname> for this target unit to all SysV
- init script service units with an LSB header referring to
- the <literal>$portmap</literal> facility.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term><filename>time-sync.target</filename></term>
- <listitem>
- <para>Services responsible for synchronizing the system
- clock from a remote source (such as NTP client
- implementations) should pull in this target and order
- themselves before it. All services where correct time is
- essential should be ordered after this unit, but not pull it
- in. systemd automatically adds dependencies of type
- <varname>After=</varname> for this target unit to all SysV
- init script service units with an LSB header referring to
- the <literal>$time</literal> facility. </para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
+ </variablelist>
+ </refsect2>
- <refsect1>
- <title>Special User Units</title>
+ <refsect2>
+ <title>Special System Units for Devices</title>
- <para>When systemd runs as a user instance, the following special
- units are available, which have similar definitions as their
- system counterparts:
- <filename>exit.target</filename>,
- <filename>default.target</filename>,
- <filename>shutdown.target</filename>,
- <filename>sockets.target</filename>,
- <filename>timers.target</filename>,
- <filename>paths.target</filename>,
- <filename>bluetooth.target</filename>,
- <filename>printer.target</filename>,
- <filename>smartcard.target</filename>,
- <filename>sound.target</filename>.</para>
- </refsect1>
+ <para>Some target units are automatically pulled in as devices of
+ certain kinds show up in the system. These may be used to
+ automatically activate various services based on the specific type
+ of the available hardware.</para>
- <refsect1>
- <title>Special Passive User Units</title>
-
- <variablelist>
- <varlistentry>
- <term><filename>graphical-session.target</filename></term>
- <listitem>
- <para>This target is active whenever any graphical session is running. It is used to stop user services which
- only apply to a graphical (X, Wayland, etc.) session when the session is terminated. Such services should
- have <literal>PartOf=graphical-session.target</literal> in their <literal>[Unit]</literal> section. A target
- for a particular session (e. g. <filename>gnome-session.target</filename>) starts and stops
- <literal>graphical-session.target</literal> with <literal>BindsTo=graphical-session.target</literal>.</para>
-
- <para>Which services are started by a session target is determined by the <literal>Wants=</literal> and
- <literal>Requires=</literal> dependencies. For services that can be enabled independently, symlinks in
- <literal>.wants/</literal> and <literal>.requires/</literal> should be used, see
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Those
- symlinks should either be shipped in packages, or should be added dynamically after installation, for example
- using <literal>systemctl add-wants</literal>, see
- <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
- </para>
-
- <example>
- <title>Nautilus as part of a GNOME session</title>
-
- <para><literal>gnome-session.target</literal> pulls in Nautilus as top-level service:</para>
-
- <programlisting>[Unit]
-Description=User systemd services for GNOME graphical session
-Wants=nautilus.service
-BindsTo=graphical-session.target</programlisting>
-
- <para><literal>nautilus.service</literal> gets stopped when the session stops:</para>
-
- <programlisting>[Unit]
-Description=Render the desktop icons with Nautilus
-PartOf=graphical-session.target
-
-[Service]
-…</programlisting>
- </example>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>graphical-session-pre.target</filename></term>
- <listitem>
- <para>This target contains services which set up the environment or global configuration of a graphical
- session, such as SSH/GPG agents (which need to export an environment variable into all desktop processes) or
- migration of obsolete d-conf keys after an OS upgrade (which needs to happen before starting any process that
- might use them). This target must be started before starting a graphical session like
- <filename>gnome-session.target</filename>.</para>
- </listitem>
- </varlistentry>
- </variablelist>
+ <variablelist>
+ <varlistentry>
+ <term><filename>bluetooth.target</filename></term>
+ <listitem>
+ <para>This target is started automatically as soon as a
+ Bluetooth controller is plugged in or becomes available at
+ boot.</para>
+ <para>This may be used to pull in Bluetooth management
+ daemons dynamically when Bluetooth hardware is found.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>printer.target</filename></term>
+ <listitem>
+ <para>This target is started automatically as soon as a
+ printer is plugged in or becomes available at boot.</para>
+
+ <para>This may be used to pull in printer management daemons
+ dynamically when printer hardware is found.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>smartcard.target</filename></term>
+ <listitem>
+ <para>This target is started automatically as soon as a
+ smartcard controller is plugged in or becomes available at
+ boot.</para>
+
+ <para>This may be used to pull in smartcard management
+ daemons dynamically when smartcard hardware is found.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>sound.target</filename></term>
+ <listitem>
+ <para>This target is started automatically as soon as a
+ sound card is plugged in or becomes available at
+ boot.</para>
+
+ <para>This may be used to pull in audio management daemons
+ dynamically when audio hardware is found.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
+
+ <refsect2>
+ <title>Special Passive System Units </title>
+
+ <para>A number of special system targets are defined that can be
+ used to properly order boot-up of optional services. These targets
+ are generally not part of the initial boot transaction, unless
+ they are explicitly pulled in by one of the implementing services.
+ Note specifically that these <emphasis>passive</emphasis> target
+ units are generally not pulled in by the consumer of a service,
+ but by the provider of the service. This means: a consuming
+ service should order itself after these targets (as appropriate),
+ but not pull it in. A providing service should order itself before
+ these targets (as appropriate) and pull it in (via a
+ <varname>Wants=</varname> type dependency).</para>
+
+ <para>Note that these passive units cannot be started manually,
+ i.e. <literal>systemctl start time-sync.target</literal> will fail
+ with an error. They can only be pulled in by dependency. This is
+ enforced since they exist for ordering purposes only and thus are
+ not useful as only unit within a transaction.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>cryptsetup-pre.target</filename></term>
+ <listitem>
+ <para>This passive target unit may be pulled in by services
+ that want to run before any encrypted block device is set
+ up. All encrypted block devices are set up after this target
+ has been reached. Since the shutdown order is implicitly the
+ reverse start-up order between units, this target is
+ particularly useful to ensure that a service is shut down
+ only after all encrypted block devices are fully
+ stopped.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>getty-pre.target</filename></term>
+ <listitem>
+ <para>A special passive target unit. Users of this target
+ are expected to pull it in the boot transaction via
+ a dependency (e.g. <varname>Wants=</varname>). Order your
+ unit before this unit if you want to make use of the console
+ just before <filename>getty</filename> is started.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>local-fs-pre.target</filename></term>
+ <listitem>
+ <para>This target unit is
+ automatically ordered before
+ all local mount points marked
+ with <option>auto</option>
+ (see above). It can be used to
+ execute certain units before
+ all local mounts.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>network.target</filename></term>
+ <listitem>
+ <para>This unit is supposed to indicate when network
+ functionality is available, but it is only very weakly
+ defined what that is supposed to mean, with one exception:
+ at shutdown, a unit that is ordered after
+ <filename>network.target</filename> will be stopped before
+ the network — to whatever level it might be set up then —
+ is shut down. It is hence useful when writing service files
+ that require network access on shutdown, which should order
+ themselves after this target, but not pull it in. Also see
+ <ulink url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
+ Services After the Network is up</ulink> for more
+ information. Also see
+ <filename>network-online.target</filename> described
+ above.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>network-pre.target</filename></term>
+ <listitem>
+ <para>This passive target unit may be pulled in by services
+ that want to run before any network is set up, for example
+ for the purpose of setting up a firewall. All network
+ management software orders itself after this target, but
+ does not pull it in.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>nss-lookup.target</filename></term>
+ <listitem>
+ <para>A target that should be used as synchronization point for all host/network name
+ service lookups. Note that this is independent of UNIX user/group name lookups for which
+ <filename>nss-user-lookup.target</filename> should be used. All services for which the
+ availability of full host/network name resolution is essential should be ordered after
+ this target, but not pull it in. systemd automatically adds dependencies of type
+ <varname>After=</varname> for this target unit to all SysV init script service units
+ with an LSB header referring to the <literal>$named</literal> facility.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>nss-user-lookup.target</filename></term>
+ <listitem>
+ <para>A target that should be used as synchronization point for all regular UNIX
+ user/group name service lookups. Note that this is independent of host/network name
+ lookups for which <filename>nss-lookup.target</filename> should be used. All services
+ for which the availability of the full user/group database is essential should be
+ ordered after this target, but not pull it in. All services which provide parts of the
+ user/group database should be ordered before this target, and pull it in. Note that this
+ unit is only relevant for regular users and groups — system users and groups are
+ required to be resolvable during earliest boot already, and hence do not need any
+ special ordering against this target.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>remote-fs-pre.target</filename></term>
+ <listitem>
+ <para>This target unit is automatically ordered before all
+ mount point units (see above) and cryptsetup devices
+ marked with the <option>_netdev</option>. It can be used to run
+ certain units before remote encrypted devices and mounts are established.
+ Note that this unit is generally not part of the initial
+ transaction, unless the unit that wants to be ordered before
+ all remote mounts pulls it in via a
+ <varname>Wants=</varname> type dependency. If the unit wants
+ to be pulled in by the first remote mount showing up, it
+ should use <filename>network-online.target</filename> (see
+ above).</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>rpcbind.target</filename></term>
+ <listitem>
+ <para>The portmapper/rpcbind pulls in this target and orders
+ itself before it, to indicate its availability. systemd
+ automatically adds dependencies of type
+ <varname>After=</varname> for this target unit to all SysV
+ init script service units with an LSB header referring to
+ the <literal>$portmap</literal> facility.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><filename>time-sync.target</filename></term>
+ <listitem>
+ <para>Services responsible for synchronizing the system
+ clock from a remote source (such as NTP client
+ implementations) should pull in this target and order
+ themselves before it. All services where correct time is
+ essential should be ordered after this unit, but not pull it
+ in. systemd automatically adds dependencies of type
+ <varname>After=</varname> for this target unit to all SysV
+ init script service units with an LSB header referring to
+ the <literal>$time</literal> facility. </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
+
+ <refsect2>
+ <title>Special Slice Units</title>
+
+ <para>There are four <literal>.slice</literal> units which form the basis of the hierarchy for
+ assignment of resources for services, users, and virtual machines or containers. See
+ <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details about slice units.</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>-.slice</filename></term>
+ <listitem>
+ <para>The root slice is the root of the slice hierarchy. It usually does not contain
+ units directly, but may be used to set defaults for the whole tree.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>system.slice</filename></term>
+ <listitem>
+ <para>By default, all system services started by
+ <command>systemd</command> are found in this slice.</para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>user.slice</filename></term>
+ <listitem>
+ <para>By default, all user processes and services started on
+ behalf of the user, including the per-user systemd instance
+ are found in this slice. This is pulled in by
+ <filename>systemd-logind.service</filename></para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>machine.slice</filename></term>
+ <listitem>
+ <para>By default, all virtual machines and containers
+ registered with <command>systemd-machined</command> are
+ found in this slice. This is pulled in by
+ <filename>systemd-machined.service</filename></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
- <title>Special Slice Units</title>
-
- <para>There are four <literal>.slice</literal> units which form the basis of the hierarchy for assignment of
- resources for services, users, and virtual machines or containers. See
- <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>7</manvolnum></citerefentry> for details about slice
- units.</para>
-
- <variablelist>
- <varlistentry>
- <term><filename>-.slice</filename></term>
- <listitem>
- <para>The root slice is the root of the slice hierarchy. It usually does not contain units directly, but may
- be used to set defaults for the whole tree.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>system.slice</filename></term>
- <listitem>
- <para>By default, all system services started by
- <command>systemd</command> are found in this slice.</para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>user.slice</filename></term>
- <listitem>
- <para>By default, all user processes and services started on
- behalf of the user, including the per-user systemd instance
- are found in this slice. This is pulled in by
- <filename>systemd-logind.service</filename></para>
- </listitem>
- </varlistentry>
-
- <varlistentry>
- <term><filename>machine.slice</filename></term>
- <listitem>
- <para>By default, all virtual machines and containers
- registered with <command>systemd-machined</command> are
- found in this slice. This is pulled in by
- <filename>systemd-machined.service</filename></para>
- </listitem>
- </varlistentry>
- </variablelist>
+ <title>Units managed by the user's service manager</title>
+
+ <refsect2>
+ <title>Special User Units</title>
+
+ <para>When systemd runs as a user instance, the following special
+ units are available, which have similar definitions as their
+ system counterparts:
+ <filename>exit.target</filename>,
+ <filename>default.target</filename>,
+ <filename>shutdown.target</filename>,
+ <filename>sockets.target</filename>,
+ <filename>timers.target</filename>,
+ <filename>paths.target</filename>,
+ <filename>bluetooth.target</filename>,
+ <filename>printer.target</filename>,
+ <filename>smartcard.target</filename>,
+ <filename>sound.target</filename>.</para>
+ </refsect2>
+
+ <refsect2>
+ <title>Special Passive User Units</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><filename>graphical-session.target</filename></term>
+ <listitem>
+ <para>This target is active whenever any graphical session is running. It is used to
+ stop user services which only apply to a graphical (X, Wayland, etc.) session when the
+ session is terminated. Such services should have
+ <literal>PartOf=graphical-session.target</literal> in their <literal>[Unit]</literal>
+ section. A target for a particular session (e. g.
+ <filename>gnome-session.target</filename>) starts and stops
+ <literal>graphical-session.target</literal> with
+ <literal>BindsTo=graphical-session.target</literal>.</para>
+
+ <para>Which services are started by a session target is determined by the
+ <literal>Wants=</literal> and <literal>Requires=</literal> dependencies. For services
+ that can be enabled independently, symlinks in <literal>.wants/</literal> and
+ <literal>.requires/</literal> should be used, see
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ Those symlinks should either be shipped in packages, or should be added dynamically
+ after installation, for example using <literal>systemctl add-wants</literal>, see
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+ </para>
+
+ <example>
+ <title>Nautilus as part of a GNOME session</title>
+
+ <para><literal>gnome-session.target</literal> pulls in Nautilus as top-level service:</para>
+
+ <programlisting>[Unit]
+ Description=User systemd services for GNOME graphical session
+ Wants=nautilus.service
+ BindsTo=graphical-session.target</programlisting>
+
+ <para><literal>nautilus.service</literal> gets stopped when the session stops:</para>
+
+ <programlisting>[Unit]
+ Description=Render the desktop icons with Nautilus
+ PartOf=graphical-session.target
+
+ [Service]
+ …</programlisting>
+ </example>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><filename>graphical-session-pre.target</filename></term>
+ <listitem>
+ <para>This target contains services which set up the environment or global configuration
+ of a graphical session, such as SSH/GPG agents (which need to export an environment
+ variable into all desktop processes) or migration of obsolete d-conf keys after an OS
+ upgrade (which needs to happen before starting any process that might use them). This
+ target must be started before starting a graphical session like
+ <filename>gnome-session.target</filename>.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
projects / thirdparty / systemd.git / blobdiff