are mostly equivalent when invoked from normal login sessions. See
<citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for more information.</para>
+
+ <para>When run as system instance, systemd interprets
+ the configuration file
+ <filename>system.conf</filename>, otherwise
+ <filename>session.conf</filename>. See
+ <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for more information.</para>
</refsect1>
<refsect1>
<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>
configuration items understood in unit
definition files.</para></listitem>
</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 at install time
+ mostly useful at install time
to generate data suitable for the
D-Bus interfaces
repository. Optionally the interface
introspection data for all interfaces
is dumped.</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>--system</option></term>
+ <term><option>--session</option></term>
+
+ <listitem><para>Tell systemd to run a
+ system instance (resp. session
+ instance), even if the process ID is
+ not 1 (resp. is 1), i.e. systemd is not
+ (resp. is) run as init process.
+ Normally it should not be necessary to
+ pass these options, as systemd
+ automatically detects the mode it is
+ started in. These options are hence of
+ little use except for
+ debugging.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>--dump-core</option></term>
+
+ <listitem><para>Dump core on crash. This switch has no effect when run as session instance.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>--crash-shell</option></term>
+
+ <listitem><para>Run shell on crash. This switch has no effect when run as session instance.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>--confirm-spawn</option></term>
+
+ <listitem><para>Ask for confirmation when spawning processes. This switch has no effect when run as session instance.</para></listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>--show-status</option></term>
+
+ <listitem><para>Show terse service status information while booting. This switch has no effect when run as session instance.</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-level=</option></term>
<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>
<para>systemd provides a dependency system between
various entities called "units". Units encapsulate
various objects that are relevant for system boot-up
- and maintainance. The majority of units are configured
+ and maintenance. The majority of units are configured
in unit configuration files, whose syntax and basic
set of options is described in
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
however some are created automatically from other
configuration or dynamically from system state. Units
- may be active (meaning started, bound, plugged in, ...
- depending on the unit type), or inactive (meaning
- stopped, unbound, unplugged, ...), as well is in the
- process of being activated or deactivated,
- i.e. between the two states. The following unit types
- are available:</para>
+ may be 'active' (meaning started, bound, plugged in,
+ ... depending on the unit type, see below), or
+ 'inactive' (meaning stopped, unbound, unplugged, ...),
+ as well as in the process of being activated or
+ deactivated, i.e. between the two states (these states
+ are called 'activating', 'deactivating'). A special
+ 'maintenance' state is available as well which is very
+ similar to 'inactive' and is entered when the service
+ failed in some way (process returned error code on
+ exit, or crashed, or an operation timed out). If this
+ state is entered the cause will be logged, for later
+ reference. Note that the various unit types may have a
+ number of additional substates, which are mapped to
+ the five generalized unit states described
+ here.</para>
+
+ <para>The following unit types are available:</para>
<orderedlist>
<listitem><para>Service units, which control
systemd units, which later may be restored by
activating the saved snapshot unit. For more
information see
- <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
+ <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<listitem><para>Timer units are useful for
triggering activation of other units based on
systemd. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
<listitem><para>Path units may be used
- activate other services when file system
+ to activate other services when file system
objects change or are modified. See
<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
list you may find in
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
+ <para>systemd knows various kinds of dependencies,
+ including positive and negative requirement
+ dependencies (i.e. <varname>Requires=</varname> and
+ <varname>Conflicts=</varname>) as well as ordering
+ dependencies (<varname>After=</varname> and
+ <varname>Before=</varname>). NB: ordering and
+ requirement dependencies are orthogonal. If only a
+ requirement dependency exists between two units
+ (e.g. <filename>foo.service</filename> requires
+ <filename>bar.service</filename>), but no ordering
+ dependency (e.g. <filename>foo.service</filename>
+ after <filename>bar.service</filename>) and both are
+ requested to start, they will be started in
+ parallel. It is a common pattern that both requirement
+ and ordering dependencies are placed between two
+ units. Also note that the majority of dependencies are
+ implicitly created and maintained by systemd. In most
+ cases it should be unnecessary to declare additional
+ dependencies manually, however it is possible to do
+ this.</para>
+
+ <para>Application programs and units (via
+ dependencies) may requests state changes of units. In
+ systemd, these requests are encapsulated as 'jobs' and
+ maintained in a job queue. Jobs may succeed or can
+ fail, their execution is ordered based on the ordering
+ dependencies of the units they have been scheduled
+ for.</para>
+
<para>On boot systemd activates the target unit
- <filename>default.target</filename> whose job it is to
+ <filename>default.target</filename> whose job is to
activate on-boot services and other on-boot units by
pulling them in via dependencies. Usually the unit
name is just an alias (symlink) for either
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details about these target units.</para>
- <para>Processes systemd spawns ared placed in
+ <para>Processes systemd spawns are placed in
individual Linux control groups named after the unit
which they belong to in the private systemd
hierarchy. (see <ulink
simply read as an alternative (though limited)
configuration file format. The SysV
<filename>/dev/initctl</filename> interface is
- provided, and comaptibility implementations of the
- various SysV client tools available. In addition to
- that various established Unix functionality such as
+ provided, and compatibility implementations of the
+ various SysV client tools are available. In addition to
+ that, various established Unix functionality such as
<filename>/etc/fstab</filename> or the
<filename>utmp</filename> database are
supported.</para>
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
+ file cannot be started by activating it
in the SysV runlevel link
farm.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
+ <refsect1>
+ <title>Kernel Command Line</title>
+
+ <para>When run as system instance systemd parses a few kernel command line arguments:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><varname>systemd.unit=</varname></term>
+
+ <listitem><para>Overrides the unit to
+ activate on boot. Defaults to
+ <filename>default.target</filename>. This
+ may be used to temporarily boot into a
+ different boot unit, for example
+ <filename>rescue.target</filename> or
+ <filename>emergency.service</filename>. See
+ <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for details about these
+ units.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.log_target=</varname></term>
+ <term><varname>systemd.log_level=</varname></term>
+ <term><varname>systemd.log_color=</varname></term>
+ <term><varname>systemd.log_location=</varname></term>
+
+ <listitem><para>Controls log output,
+ with the same effect as the
+ <varname>$SYSTEMD_LOG_TARGET</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>, <varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LOCATION</varname>
+ environment variables described above.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.dump_core=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ systemd dumps core when it
+ crashes. Otherwise no core dump is
+ created. Defaults to
+ <option>true</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.crash_shell=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ systemd spawns a shell when it
+ crashes. Otherwise no core dump is
+ created. Defaults to
+ <option>false</option>, for security
+ reasons, as the shell is not protected
+ by any password
+ authentication.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.crash_chvt=</varname></term>
+
+ <listitem><para>Takes an integer
+ argument. If positive systemd
+ activates the specified virtual
+ terminal when it crashes. Defaults to
+ <literal>-1</literal>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>systemd.show_status=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ shows terse service status updates on
+ the console during bootup. Defaults to
+ <option>true</option>.</para></listitem>
+ </varlistentry>
+
+ </variablelist>
+ </refsect1>
+
<refsect1>
<title>Sockets and FIFOs</title>
~ianmdlvl / elogind.git / blobdiff