systemd/man/systemd.special.xml

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2010-05-17 04:45:11 +08:00
<?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">
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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>emergency.service</filename></para>
<para><filename>local-fs.target</filename></para>
<para><filename>network.target</filename></para>
<para><filename>nss-lookup.target</filename></para>
<para><filename>remote-fs.target</filename></para>
<para><filename>rpcbind.target</filename></para>
<para><filename>rtc-set.target</filename></para>
<para><filename>shutdown.target</filename></para>
<para><filename>sigpwr.target</filename></para>
<para><filename>sockets.target</filename></para>
<para><filename>swap.target</filename></para>
<para><filename>syslog.target</filename></para>
<para><filename>systemd-initctl.service</filename></para>
<para><filename>systemd-initctl.socket</filename></para>
<para><filename>systemd-logger.service</filename></para>
<para><filename>systemd-logger.socket</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>emergency.service</filename></term>
<listitem>
<para>A special service 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>local-fs.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to all mount units that
refer to local mount
points. In addition, systemd
adds dependencies of type
Wants to those mounts listed
in
<filename>/etc/fstab</filename>
that have the
<literal>auto</literal> and
<literal>comment=systemd.mount</literal>
mount options set.</para>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$local_fs</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>network.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$network</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>nss-lookup.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$named</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-fs.target</filename></term>
<listitem>
<para>Similar to <filename>local-fs.target</filename>, but for remote mount points.</para>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$remote-fs</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>rpcbind.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$rpcbind</literal>
facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>rtc-set.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts with an
LSB header referring to the
<literal>$time</literal>
facility.</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 Wants dependencies
from this unit to their
service unit during
installation.</para>
<para>systemd automatically
adds dependencies of type
Conflicts to this target unit
for all SysV init scripts 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 the
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 from this
unit to 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>syslog.target</filename></term>
<listitem>
<para>systemd automatically
adds dependencies of type
After to this target unit for
all SysV init scripts 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_NAME@</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 used internally
by systemd to provide syslog
logging to started
processes.</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>.</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>local-fs.target</filename>,
<filename>remote-fs.target</filename>,
<filename>shutdown.target</filename>,
<filename>sockets.target</filename>,
<filename>swap.target</filename>.</para>
</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>