eudev/man/systemd.xml

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<?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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Copyright 2010 Lennart Poettering
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<refentry id="systemd">
<refentryinfo>
<title>systemd</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</refentrytitle>
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<manvolnum>1</manvolnum>
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</refmeta>
<refnamediv>
<refname>systemd</refname>
<refpurpose>systemd System and Session Manager</refpurpose>
</refnamediv>
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<refsynopsisdiv>
<cmdsynopsis>
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<command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command>
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</cmdsynopsis>
<cmdsynopsis>
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<command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command>
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</cmdsynopsis>
</refsynopsisdiv>
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<refsect1>
<title>Description</title>
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<para>systemd is a system and session manager for
Linux operating systems. When run as first process on
boot (as PID 1) it may act as init system that brings
up and maintains userspace.</para>
<para>For compatibility with SysV if systemd is called
as <command>init</command> and a PID that is not
1 it will execute <command>telinit</command> and pass
all command line arguments unmodified. That means
<command>init</command> and <command>telinit</command>
are mostly equivalent when invoked from normal login sessions. See
<citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for more information.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
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<term><option>-h</option></term>
<term><option>--help</option></term>
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<listitem><para>Prints a short help
text and exits.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--unit=</option></term>
<listitem><para>Set default unit to
activate on startup. If not specified
defaults to
<filename>default.target</filename>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--running-as=</option></term>
<listitem><para>Tell systemd to run in
a particular mode. Argument is one of
<option>system</option>,
<option>session</option>. Normally it
should not be necessary to pass this
option, as systemd automatically
detects the mode it is started
in. This call is hence of little use
except for
debugging.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--test</option></term>
<listitem><para>Determine startup
sequence, dump it and exit. This is an
option useful for debugging
only.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--dump-configuration-items</option></term>
<listitem><para>Dump understood unit
configuration items. This outputs a
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terse but complete list of
configuration items understood in unit
definition files.</para></listitem>
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</varlistentry>
<varlistentry>
<term><option>--confirm-spawn</option></term>
<listitem><para>Ask for confirmation when spawning processes.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--introspect=</option></term>
<listitem><para>Extract D-Bus
interface introspection data. This is
mostly useful at build ot install time
to generate data suitable for the
D-Bus interfaces
repository. Optionally the interface
name for the introspection data may be
specified. If omitted the
introspection data for all interfaces
is dumped.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--log-level=</option></term>
<listitem><para>Set log level. As
argument this accepts a numerical log
level or the well-known <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
symbolic names (lowercase):
<option>emerg</option>,
<option>alert</option>,
<option>crit</option>,
<option>err</option>,
<option>warning</option>,
<option>notice</option>,
<option>info</option>,
<option>debug</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--log-target=</option></term>
<listitem><para>Set log
target. Argument must be one of
<option>console</option>,
<option>syslog</option>,
<option>kmsg</option>,
<option>syslog-or-kmsg</option>,
<option>null</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--log-color=</option></term>
<listitem><para>Highlight important
log messages. Argument is a boolean
value. If the argument is omitted it
defaults to
<option>true</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--log-location=</option></term>
<listitem><para>Include code location
in log messages. This is mostly
relevant for debugging
purposes. Argument is a boolean
value. If the argument is omitted
it defaults to
<option>true</option>.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
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<refsect1>
<title>Directories</title>
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<variablelist>
<varlistentry>
<term>System unit directories</term>
<listitem><para>The systemd system
manager reads unit configuration from
various directories. Packages that
want to install unit files shall place
them in the directory returned by
<command>pkg-config systemd
--variable=systemdsystemunitdir</command>. Other
directories checked are
<filename>/usr/local/share/systemd/system</filename>
and
<filename>/usr/share/systemd/system</filename>. User
configuration always takes
precedence. <command>pkg-config
systemd
--variable=systemdsystemconfdir</command>
returns the path of the system
configuration directory. Packages
should alter this directory only with
the
<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
tool.</para></listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term>Session unit directories</term>
<listitem><para>Similar rules apply
for the session unit
directories. However, here the <ulink
url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
Base Directory specification</ulink>
is followed to find
units. Applications should place their
unit files in the directory returned
by <command>pkg-config systemd
--variable=systemdsessionunitdir</command>. Global
configuration is done in the
directory reported by
<command>pkg-config systemd
--variable=systemdsessionconfdir</command>. The
<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
tool can handle both global (i.e. for
all users) and private (for one user)
enabling/disabling of
units.</para></listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term>SysV init scripts directory</term>
<listitem><para>The location of the
SysV init script directory varies
between distributions. If systemd
cannot find a native unit file for a
requested service it will look for a
SysV init script of the same name
(with the
<filename>.service</filename> suffix
removed).</para></listitem>
</varlistentry>
</variablelist>
<variablelist>
<varlistentry>
<term>SysV runlevel link farm directory</term>
<listitem><para>The location of the
SysV runlevel link farm directory
varies between distributions. systemd
will take the link farm into account
when figuring out whether a service
shall be enabled. Note that a service
unit with a native unit configuration
file can be started by activating it
in the SysV runlevel link
farm.</para></listitem>
</varlistentry>
</variablelist>
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</refsect1>
<refsect1>
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<title>Signals</title>
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<variablelist>
<varlistentry>
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<term>SIGTERM</term>
<listitem><para>Upon receiving this
signal the systemd system manager
serializes its state, reexecutes
itself and deserializes the saved
state again. This is mostly equivalent
to <command>systemctl
daemon-reexec</command>.</para>
<para>systemd session managers will
start the
<filename>exit.target</filename> unit
when this signal is received. This is
mostly equivalent to
<command>systemctl --session start
exit.target</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGINT</term>
<listitem><para>Upon receiving this
signal the systemd system manager will
start the
<filename>ctrl-alt-del.target</filename> unit. This
is mostly equivalent to
<command>systemctl start
ctl-alt-del.target</command>.</para>
<para>systemd session managers
treat this signal the same way as
SIGTERM.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGWINCH</term>
<listitem><para>When this signal is
received the systemd system manager
will start the
<filename>kbrequest.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
kbrequest.target</command>.</para>
<para>This signal is ignored by
systemd session
managers.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGPWR</term>
<listitem><para>When this signal is
received the systemd manager
will start the
<filename>sigpwr.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
sigpwr.target</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGUSR1</term>
<listitem><para>When this signal is
received the systemd manager will try
to reconnect to the D-Bus
bus.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGUSR2</term>
<listitem><para>When this signal is
received the systemd manager will log
its complete state in human readable
form. The data logged is the same as
printed by <command>systemctl
dump</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGHUP</term>
<listitem><para>Reloads the complete
daemon configuration. This is mostly
equivalent to <command>systemctl
daemon-reload</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGRTMIN+0</term>
<listitem><para>Enters default mode, starts the
<filename>default.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
default.target</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGRTMIN+1</term>
<listitem><para>Enters rescue mode,
starts the
<filename>rescue.target</filename>
unit. This is mostly equivalent to
<command>systemctl isolate
rescue.target</command>.</para></listitem>
</varlistentry>
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<varlistentry>
<term>SIGRTMIN+2</term>
<listitem><para>Enters emergency mode,
starts the
<filename>emergency.service</filename>
unit. This is mostly equivalent to
<command>systemctl isolate
emergency.service</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGRTMIN+3</term>
<listitem><para>Halts the machine,
starts the
<filename>halt.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
halt.target</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGRTMIN+4</term>
<listitem><para>Powers off the machine,
starts the
<filename>poweroff.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
poweroff.target</command>.</para></listitem>
</varlistentry>
<varlistentry>
<term>SIGRTMIN+5</term>
<listitem><para>Reboots the machine,
starts the
<filename>reboot.target</filename>
unit. This is mostly equivalent to
<command>systemctl start
reboot.target</command>.</para></listitem>
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</varlistentry>
</variablelist>
</refsect1>
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<refsect1>
<title>Environment</title>
<variablelist>
<varlistentry>
<term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
<listitem><para>systemd reads the
log level from this environment
variable. This can be overriden with
<option>--log-level=</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_LOG_TARGET</varname></term>
<listitem><para>systemd reads the
log target from this environment
variable. This can be overriden with
<option>--log-target=</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_LOG_COLOR</varname></term>
<listitem><para>Controls whether
systemd highlights important log
messages. This can be overriden with
<option>--log-color=</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_LOG_LOCATION</varname></term>
<listitem><para>Controls whether
systemd prints the code location along
with log messages. This can be
overriden with
<option>--log-location=</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$XDG_CONFIG_HOME</varname></term>
<term><varname>$XDG_CONFIG_DIRS</varname></term>
<term><varname>$XDG_DATA_HOME</varname></term>
<term><varname>$XDG_DATA_DIRS</varname></term>
<listitem><para>The systemd session
manager uses these variables in
accordance to the <ulink
url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG
Base Directory specification</ulink>
to find its configuration.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_UNIT_PATH</varname></term>
<listitem><para>Controls where systemd
looks for unit
files.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term>
<listitem><para>Controls where systemd
looks for SysV init scripts.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term>
<listitem><para>Controls where systemd
looks for SysV init script runlevel link
farms.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$LISTEN_PID</varname></term>
<term><varname>$LISTEN_FDS</varname></term>
<listitem><para>Set by systemd for
supervised processes during
socket-based activation. See
<citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information.
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>$NOTIFY_SOCKET</varname></term>
<listitem><para>Set by systemd for
supervised processes for status and
start-up completion notification. See
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information.
</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
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<refsect1>
<title>Sockets and FIFOs</title>
<variablelist>
<varlistentry>
<term><filename>@/org/freedesktop/systemd1/notify</filename></term>
<listitem><para>Daemon status
notification socket. This is an AF_UNIX
datagram socket in the Linux abstract
namespace, and is used to implement
the daemon notification logic as
implemented by
<citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
</varlistentry>
<varlistentry>
<term><filename>@/org/freedesktop/systemd1/logger</filename></term>
<listitem><para>Used internally by the
<filename>systemd-logger.service</filename>
unit to connect STDOUT and/or STDERR
of spawned processes to
<citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
or the kernel log buffer. This is an
AF_UNIX stream socket in the Linux
abstract namespace.</para></listitem>
</varlistentry>
<varlistentry>
<term><filename>@/org/freedesktop/systemd1/private</filename></term>
<listitem><para>Used internally as
communication channel between
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
and the systemd process. This is an
AF_UNIX stream socket in the Linux
abstract namespace. This interface is
private to systemd and should not be
used in external
projects.</para></listitem>
</varlistentry>
<varlistentry>
<term><filename>/dev/initctl</filename></term>
<listitem><para>Limited compatibility
support for the SysV client interface,
as implemented by the
<filename>systemd-initctl.service</filename>
unit. This is a named pipe in the file
system. This interface is obsolete and
should not be used in new
applications.</para></listitem>
</varlistentry>
</variablelist>
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</refsect1>
<refsect1>
<title>See Also</title>
<para>
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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</para>
</refsect1>
</refentry>