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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>

<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>halt.target</filename>,

<filename>hibernate.target</filename>,

<filename>hybrid-sleep.target</filename>,

<filename>initrd-fs.target</filename>,

<filename>kbrequest.target</filename>,

<filename>kexec.target</filename>,

<filename>local-fs.target</filename>,

<filename>local-fs-pre.target</filename>,

<filename>multi-user.target</filename>,

<filename>network.target</filename>,

<filename>nss-lookup.target</filename>,

<filename>nss-user-lookup.target</filename>,

<filename>paths.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>initrd-root-fs.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>system-update.target</filename>,

<filename>time-sync.target</filename>,

<filename>timers.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 basic boot-up.</para>

<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>Usually this should

pull-in all mount points, swap

devices, sockets, timers, and

path units and other basic

initialization necessary for

general purpose

daemons.</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>

<para>This may be used to pull

in Bluetooth management

daemons dynamically when

Bluetooth hardware is

found.</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 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 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>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 start

this unit.</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 fround in

<filename>/etc/fstab</filename>

that have the

<option>auto</option> and

<option>x-initrd.mount</option>

mount options set.

</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><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>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>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-uer.target</varname>

in the unit's

<literal>[Install]</literal>

section.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>network.target</filename></term>

<listitem>

<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>

<para>This unit is supposed to

indicate when the network is

"up", but it is only very

loosely defined what that is

supposed to mean. Also see <ulink

url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running

Services After the Network is

up</ulink> for more

information.</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

<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. </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 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>

<para>This may be used to pull

in printer management

daemons dynamically when

printer hardware is

found.</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

<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>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>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>rpcbind.target</filename></term>

<listitem>

<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>$portmap</literal>

facility.</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>multi-user.target</filename>

(for runlevel 2) or

<filename>graphical.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>

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>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 printer management

daemons dynamically when

smartcard hardware is

found.</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>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 printer

hardware is found.</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>

</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="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog

Interface</ulink>

document.</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

<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>

<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 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>,

<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>