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<refentry id="systemd.special">
<refentryinfo>
<title>systemd.special</title>
<productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
</refentryinfo>
<refmeta>
</refnamediv>
<refsynopsisdiv><para>
- <!-- sort alphabetically, targets first -->
- <filename>basic.target</filename>,
+ <!-- sort alphabetically, targets first --><filename>basic.target</filename>,
<filename>bluetooth.target</filename>,
<filename>cryptsetup-pre.target</filename>,
<filename>cryptsetup.target</filename>,
<filename>halt.target</filename>,
<filename>hibernate.target</filename>,
<filename>hybrid-sleep.target</filename>,
+ <filename>suspend-then-hibernate.target</filename>,
<filename>initrd-fs.target</filename>,
<filename>initrd-root-device.target</filename>,
<filename>initrd-root-fs.target</filename>,
<filename>poweroff.target</filename>,
<filename>printer.target</filename>,
<filename>reboot.target</filename>,
+ <filename>remote-cryptsetup.target</filename>,
<filename>remote-fs-pre.target</filename>,
<filename>remote-fs.target</filename>,
<filename>rescue.target</filename>,
<filename>suspend.target</filename>,
<filename>swap.target</filename>,
<filename>sysinit.target</filename>,
- <filename>syslog.socket</filename>,
<filename>system-update.target</filename>,
+ <filename>system-update-pre.target</filename>,
<filename>time-sync.target</filename>,
<filename>timers.target</filename>,
<filename>umount.target</filename>,
- <!-- slices -->
- <filename>-.slice</filename>,
+ <!-- slices --><filename>-.slice</filename>,
<filename>system.slice</filename>,
<filename>user.slice</filename>,
<filename>machine.slice</filename>,
- <!-- the rest -->
+ <!-- the rest --><filename>-.mount</filename>,
<filename>dbus.service</filename>,
<filename>dbus.socket</filename>,
<filename>display-manager.service</filename>,
+ <filename>init.scope</filename>,
+ <filename>syslog.socket</filename>,
<filename>system-update-cleanup.service</filename>
</para></refsynopsisdiv>
<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>
</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>graphical.target</filename></term>
<listitem>
<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>
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>
<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>
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>
<para>A special target unit for shutting down and powering
off the system.</para>
- <para>Applications wanting to reboot the system should not start this unit
+ <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
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>
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.</para>
+ 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>
SysV.</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>runlevel2.target</filename></term>
<term><filename>runlevel3.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>user.slice</filename>,
- <filename>system.slice</filename>, <filename>machines.slice</filename> slice units, as well as the root
- slice unit <filename>-.slice</filename> are pulled in and ordered before this unit (see below).</para>
+ 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>
</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.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. 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>
+ <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>
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>
information. Also see
<filename>network-online.target</filename> described
above.</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>$network</literal> facility.</para>
</listitem>
</varlistentry>
<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 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>$named</literal>
- facility.</para>
+ <para>A target that should be used as synchronization point for all host/network name service lookups. Note
+ that this is independent of UNIX user/group name lookups for which <filename>nss-user-lookup.target</filename>
+ should be used. All services for which the availability of full host/network name resolution is essential
+ should be ordered after this target, but not pull it in. systemd automatically adds dependencies of type
+ <varname>After=</varname> for this target unit to all SysV init script service units with an LSB header
+ referring to the <literal>$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 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. Note that system users are always
- resolvable, and hence do not require any special ordering
- against this target.</para>
+ <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
- remote mount point units (see above). It can be used to run
- certain units before the remote mounts are established. Note
- that this unit is generally not part of the initial
+ 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
<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.</para>
+ <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 hierarchy. It
- usually does not contain units directly, but may be used to
- set defaults for the whole tree.</para>
+ <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>
<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.</para>
+ are found in this slice. This is pulled in by
+ <filename>systemd-logind.service</filename></para>
</listitem>
</varlistentry>
<listitem>
<para>By default, all virtual machines and containers
registered with <command>systemd-machined</command> are
- found in this slice.
- </para>
+ found in this slice. This is pulled in by
+ <filename>systemd-machined.service</filename></para>
</listitem>
</varlistentry>
</variablelist>
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
</para>
</refsect1>
projects / thirdparty / systemd.git / blobdiff