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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>ctrl-alt-del.target</filename>,

<filename>dbus.service</filename>,

<filename>dbus.target</filename>,

<filename>default.target</filename>,

<filename>display-manager.service</filename>,

<filename>emergency.target</filename>,

<filename>exit.service</filename>,

<filename>graphical.target</filename>,

<filename>halt.target</filename>,

<filename>kbrequest.target</filename>,

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

<filename>mail-transfer-agent.target</filename>,

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

<filename>network.target</filename>,

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

<filename>poweroff.target</filename>,

<filename>reboot.target</filename>,

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

<filename>rescue.target</filename>,

<filename>rpcbind.target</filename>,

<filename>rtc-set.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>sockets.target</filename>,

<filename>swap.target</filename>,

<filename>sysinit.target</filename>,

<filename>@SPECIAL_SYSLOG_SERVICE@</filename>,

<filename>syslog.target</filename>,

<filename>systemd-initctl.service</filename>,

<filename>systemd-initctl.socket</filename>,

<filename>systemd-logger.service</filename>,

<filename>systemd-logger.socket</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>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>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>

<para>Units should generally

avoid depending on this unit

directly and instead refer to

the

<filename>dbus.target</filename>

unit instead, which pulls this

one in directly or indirectly

via socket-based activation.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>dbus.target</filename></term>

<listitem>

<para>Administrators should

ensure that this target pulls

in a service unit with the

name or alias of

<filename>dbus.service</filename>

(or a socket unit that

activates this

service).</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

overriden with the

<varname>systemd.default=</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>xdm.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.default=</varname>

and has otherwise little use.

</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>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>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>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-argent</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>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>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>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>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>rtc-set.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>runlevel2.target</filename></term>

<listitem>

<para>This is a target that is

called whever 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 whever 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 whever 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 whever 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>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>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>@SPECIAL_SYSLOG_SERVICE@</filename></term>

<listitem>

<para>A special unit for the

syslog daemon. As soon as

this service is fully started

up systemd will connect to it

and use it for logging if it

has been configured for

that.</para>

<para>Units should generally

avoid depending on this unit

directly and instead refer to

the

<filename>syslog.target</filename>

unit instead, which pulls this

one in directly or indirectly

via socket-based activation.</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>

<para>Administrators should

ensure that this target pulls

in a service unit with the

name or alias of

<filename>@SPECIAL_SYSLOG_SERVICE@</filename>

(or a socket unit that

activates this

service).</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>systemd-initctl.service</filename></term>

<listitem>

<para>This provides

compatibility with the SysV

/dev/initctl file system FIFO

for communication with the

init system.</para>

<para>This is a

socket-activated service, see

<filename>system-initctl.socket</filename>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>systemd-initctl.socket</filename></term>

<listitem>

<para>Socket activation unit

for

<filename>system-initctl.service</filename>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>systemd-logger.service</filename></term>

<listitem>

<para>This is internally used

by systemd to provide syslog

logging to the processes it

maintains.</para>

<para>This is a

socket-activated service, see

<filename>system-logger.socket</filename>.</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>systemd-logger.socket</filename></term>

<listitem>

<para>Socket activation unit

for

<filename>system-logger.service</filename>. systemd

will automatically add

dependencies of types Requires

and After to all units that

have been configured for

stdout or stderr to be

connected to syslog or the

kernel log buffer.</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 Session Units</title>

<para>When systemd runs as a service instance, the

following special units are available, which have

similar definitions as their system counterparts:

<filename>default.target</filename>,

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

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

<filename>shutdown.target</filename>,

<filename>sockets.target</filename>,

<filename>swap.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.service</filename></term>

<listitem>

<para>A special service unit

for shutting down the

session.</para>

<para>Applications wanting to

terminate the session should

start this unit. If systemd

receives SIGTERM or SIGINT

when running as session 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

session exit.</para>

</listitem>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<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>

</para>

</refsect1>

</refentry>