<filename>shutdown.target</filename>,
<filename>sigpwr.target</filename>,
<filename>sleep.target</filename>,
+ <filename>slices.target</filename>,
<filename>smartcard.target</filename>,
<filename>sockets.target</filename>,
<filename>sound.target</filename>,
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
+ <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
<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
+ pressed on the console. Usually, this should be aliased
(symlinked) to <filename>reboot.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>default.target</filename></term>
<listitem>
- <para>The default unit systemd starts at bootup. Usually
+ <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>
<varlistentry>
<term><filename>display-manager.service</filename></term>
<listitem>
- <para>The display manager service. Usually this should be
+ <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>
<term><filename>emergency.target</filename></term>
<listitem>
- <para>A special target unit that starts an emergency shell
- on the main console. This unit is supposed to be used with
- the kernel command line option
- <varname>systemd.unit=</varname> and has otherwise little
- use.
- </para>
+ <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 also works in containers and is
- equivalent to <filename>poweroff.target</filename> on
- non-container systems.</para>
+ user service manager. It is equivalent to
+ <filename>poweroff.target</filename> on non-container
+ systems, and also works in containers.</para>
- <para>Applications wanting to terminate the user service
- manager should start this unit. If systemd receives
+ <para>systemd will start this unit when it receives a
+ request to shut down over D-Bus or a
<constant>SIGTERM</constant> or <constant>SIGINT</constant>
- when running as user service daemon, it will start this
- unit.</para>
+ signal when running as user service daemon.</para>
- <para>Normally, this pulls in
- <filename>shutdown.target</filename> which in turn should be
- conflicted by all units that want to be shut down on user
- service manager exit.</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>
<varlistentry>
<term><filename>rescue.target</filename></term>
<listitem>
- <para>A special target unit for setting up the base system
- and a rescue shell.</para>
+ <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.</para>
- <para><filename>runlevel1.target</filename> is an alias for
- this target unit, for compatibility with SysV.</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>
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>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>
+
+ <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
+ units (see
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) that shall be active after boot.</para>
<varlistentry>
<term><filename>umount.target</filename></term>
<listitem>
- <para>A special target unit that umounts all mount and
+ <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
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 --
+ 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
projects / thirdparty / systemd.git / blobdiff