eudev/man/systemd.special.xml

866 lines
48 KiB
XML

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<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>
<refentrytitle>systemd.special</refentrytitle>
<manvolnum>7</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.special</refname>
<refpurpose>Special systemd units</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>basic.target</filename>,
<filename>bluetooth.target</filename>,
<filename>ctrl-alt-del.target</filename>,
<filename>cryptsetup.target</filename>,
<filename>dbus.service</filename>,
<filename>dbus.socket</filename>,
<filename>default.target</filename>,
<filename>display-manager.service</filename>,
<filename>emergency.target</filename>,
<filename>exit.target</filename>,
<filename>final.target</filename>,
<filename>getty.target</filename>,
<filename>graphical.target</filename>,
<filename>hibernate.target</filename>,
<filename>http-daemon.target</filename>,
<filename>halt.target</filename>,
<filename>kbrequest.target</filename>,
<filename>kexec.target</filename>,
<filename>local-fs.target</filename>,
<filename>local-fs-pre.target</filename>,
<filename>mail-transfer-agent.target</filename>,
<filename>multi-user.target</filename>,
<filename>network.target</filename>,
<filename>nss-lookup.target</filename>,
<filename>nss-user-lookup.target</filename>,
<filename>poweroff.target</filename>,
<filename>printer.target</filename>,
<filename>reboot.target</filename>,
<filename>remote-fs.target</filename>,
<filename>remote-fs-pre.target</filename>,
<filename>rescue.target</filename>,
<filename>rpcbind.target</filename>,
<filename>runlevel2.target</filename>,
<filename>runlevel3.target</filename>,
<filename>runlevel4.target</filename>,
<filename>runlevel5.target</filename>,
<filename>shutdown.target</filename>,
<filename>sigpwr.target</filename>,
<filename>sleep.target</filename>,
<filename>smartcard.target</filename>,
<filename>sockets.target</filename>,
<filename>sound.target</filename>,
<filename>suspend.target</filename>,
<filename>swap.target</filename>,
<filename>sysinit.target</filename>,
<filename>syslog.socket</filename>,
<filename>syslog.target</filename>,
<filename>system-update.target</filename>,
<filename>time-sync.target</filename>,
<filename>umount.target</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A few units are treated specially by
systemd. They have special internal semantics and
cannot be renamed.</para>
</refsect1>
<refsect1>
<title>Special System Units</title>
<variablelist>
<varlistentry>
<term><filename>basic.target</filename></term>
<listitem>
<para>A special target unit
covering early boot-up.</para>
<para>systemd automatically
adds dependencies of the types
Requires and After for this
target unit to all SysV
service units configured for
runlevel 1 to 5.</para>
<para>Usually this should pull-in
all sockets, mount points,
swap devices and other basic
initialization necessary for
the general purpose
daemons. Most normal daemons
should have dependencies of
type After and Requires on
this unit.</para>
</listitem>
</varlistentry>
<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>
</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 system bus. 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
<literal>Type=dbus</literal>
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>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with a LSB header
referring to the
<literal>$x-display-manager</literal>
facility, for compatibility
with Debian.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>emergency.target</filename></term>
<listitem>
<para>A special target unit
that starts an emergency
shell on the main
console. This unit is supposed
to be used with the kernel
command line option
<varname>systemd.unit=</varname>
and has otherwise little use.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>final.target</filename></term>
<listitem>
<para>A special target unit
that is used during the
shutdown logic and may be used
to pull in late services after
all normal services are
already terminated and all
mounts unmounted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>getty.target</filename></term>
<listitem>
<para>A special target unit
that pulls in all local TTY
<filename>getty</filename> instances.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>graphical.target</filename></term>
<listitem>
<para>A special target unit
for setting up a graphical
login screen. This pulls in
<filename>multi-user.target</filename>.</para>
<para>Units that are needed
for graphical login shall add
Wants dependencies for their
unit to this unit (or
<filename>multi-user.target</filename>)
during installation.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>hibernate.target</filename></term>
<listitem>
<para>A special target unit
for hibernating the
system. This pulls in
<filename>sleep.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>http-daemon.target</filename></term>
<listitem>
<para>A target for pulling in
an HTTP server if there is
any.</para>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with a LSB header
referring to the
<literal>$httpd</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>halt.target</filename></term>
<listitem>
<para>A special target unit
for shutting down and halting the system.</para>
<para>Applications wanting to
halt the system should start
this unit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>kbrequest.target</filename></term>
<listitem>
<para>systemd starts this
target whenever Alt+ArrowUp is
pressed on the console. This
is a good candidate to be
aliased (symlinked) to
<filename>rescue.target</filename>.</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 with kexec should start
this unit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>local-fs.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to all mount units that
refer to local mount points
for this target unit. In
addition, systemd adds
dependencies of type Wants to
this target unit for those
mounts listed in
<filename>/etc/fstab</filename>
that have the
<option>auto</option> and
<option>comment=systemd.mount</option>
mount options set.</para>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$local_fs</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>local-fs-pre.target</filename></term>
<listitem>
<para>This target unit is
automatically ordered before
all local mount points marked
with <option>auto</option>
(see above). It can be used to
execute certain units before
all local mounts.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>mail-transfer-agent.target</filename></term>
<listitem>
<para>The mail transfer agent
(MTA) service. Usually this
should pull-in all units
necessary for
sending/receiving mails on the
local host.</para>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$mail-transfer-agent</literal>
or
<literal>$mail-transport-agent</literal>
facilities, for compatibility
with Debian.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>multi-user.target</filename></term>
<listitem>
<para>A special target unit
for setting up a multi-user
system (non-graphical). This
is pulled in by
<filename>graphical.target</filename>.</para>
<para>Units that are needed
for a multi-user system shall
add Wants dependencies to
this unit for their unit during
installation.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>network.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$network</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<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. systemd
automatically adds
dependencies of type After for
this target unit to all SysV
init script service units with
an LSB header referring to the
<literal>$named</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>nss-user-lookup.target</filename></term>
<listitem>
<para>A target that should be
used as synchronization point
for all user/group name
service lookups. Note that
this is independent of
host/network name lookups for
which
<filename>nss-lookup.target</filename>
should be used. </para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>poweroff.target</filename></term>
<listitem>
<para>A special target unit
for shutting down and powering off the system.</para>
<para>Applications wanting to
power off the system should start
this unit.</para>
<para><filename>runlevel0.target</filename>
is an alias for this target
unit, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>printer.target</filename></term>
<listitem>
<para>This target is started
automatically as soon as a
printer is plugged in or
becomes available at
boot.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>reboot.target</filename></term>
<listitem>
<para>A special target unit
for shutting down and rebooting the system.</para>
<para>Applications wanting to
reboot the system should start
this unit.</para>
<para><filename>runlevel6.target</filename>
is an alias for this target
unit, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-fs.target</filename></term>
<listitem>
<para>Similar to
<filename>local-fs.target</filename>,
but for remote mount
points.</para>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$remote_fs</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-fs-pre.target</filename></term>
<listitem>
<para>This target unit is
automatically ordered before
all remote mount points marked
with <option>auto</option>
(see above). It can be used to
execute certain units before
all remote mounts.</para>
</listitem>
</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><filename>runlevel1.target</filename>
is an alias for this target
unit, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>rpcbind.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$rpcbind</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>runlevel2.target</filename></term>
<listitem>
<para>This is a target that is
called whenever the SysV
compatibility code asks for
runlevel 2. It is a good idea
to make this an alias for
(i.e. symlink to)
<filename>multi-user.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>runlevel3.target</filename></term>
<listitem>
<para>This is a target that is
called whenever the SysV
compatibility code asks for
runlevel 3. It is a good idea
to make this an alias for
(i.e. symlink to)
<filename>multi-user.target</filename>
or
<filename>graphical.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>runlevel4.target</filename></term>
<listitem>
<para>This is a target that is
called whenever the SysV
compatibility code asks for
runlevel 4. It is a good idea
to make this an alias for
(i.e. symlink to)
<filename>multi-user.target</filename>
or
<filename>graphical.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>runlevel5.target</filename></term>
<listitem>
<para>This is a target that is
called whenever the SysV
compatibility code asks for
runlevel 5. It is a good idea
to make this an alias for
(i.e. symlink to)
<filename>multi-user.target</filename>
or
<filename>graphical.target</filename>.</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 Conflicts
dependencies to this unit for
their service unit, which is
implicitly done when
<varname>DefaultDependencies=yes</varname>
is set (the default).</para>
<para>systemd automatically
adds dependencies of type
Conflicts to this target unit
for all SysV init script
service units that shall be
terminated in SysV runlevels 0
or 6.</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>
and
<filename>hibernate.target</filename>
and may be used to hook units
into the sleep state
logic.</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>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sockets.target</filename></term>
<listitem>
<para>A special target unit
that sets up all service
sockets.</para>
<para>Services that can be
socket-activated shall add
Wants dependencies to this
unit for their socket unit
during installation.</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>
</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>A special target unit
covering early boot-up scripts.</para>
<para>systemd automatically
adds dependencies of the types
Wants and After for all
SysV service units configured
for runlevels that are not 0
to 6 to this target unit.
This covers the special
boot-up runlevels some
distributions have, such as S
or b.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>syslog.socket</filename></term>
<listitem>
<para>The socket unit where
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="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
Interface</ulink>
document.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>syslog.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After for this target unit to
all SysV init script service
units with an LSB header
referring to the
<literal>$syslog</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>system-update.target</filename></term>
<listitem>
<para>A special target unit
that is used for off-line
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 the <ulink
url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System
Updates
Specification</ulink>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>time-sync.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After 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>
<varlistentry>
<term><filename>umount.target</filename></term>
<listitem>
<para>A special target unit
that umounts 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>
<refsect1>
<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>default.target</filename>,
<filename>shutdown.target</filename>,
<filename>sockets.target</filename></para>
<para>In addition the following special unit is
understood only when systemd runs as service instance:</para>
<variablelist>
<varlistentry>
<term><filename>exit.target</filename></term>
<listitem>
<para>A special service unit
for shutting down the
user service manager.</para>
<para>Applications wanting to
terminate the user service
manager should start this
unit. If systemd receives
SIGTERM or SIGINT when running
as user service daemon it will
start this unit.</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>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>