execute: optionally ignore return status of invoked commands

[elogind.git] / man / systemd.xml

diff --git a/man/systemd.xml b/man/systemd.xml
index 007705e4943ebaa296505c8e2195d2834be4747c..0798f231b93e84df1413924c677d26da20e12ffc 100644 (file)
--- a/man/systemd.xml
+++ b/man/systemd.xml
@@ -73,6 +73,13 @@
                 are mostly equivalent when invoked from normal login sessions. See
                 <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                 for more information.</para>
                 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>
         </refsect1>
 
         <refsect1>


@@ -88,6 +95,37 @@
                                 <listitem><para>Prints a short help
                                 text and exits.</para></listitem>
                         </varlistentry>
                                 <listitem><para>Prints a short help
                                 text and exits.</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
+                                terse but complete list of
+                                configuration items understood in unit
+                                definition files.</para></listitem>
+                        </varlistentry>
+                        <varlistentry>
+                                <term><option>--introspect=</option></term>
+
+                                <listitem><para>Extract D-Bus
+                                interface introspection data. This is
+                                mostly useful at 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>--unit=</option></term>
 
                         <varlistentry>
                                 <term><option>--unit=</option></term>
 


@@ -111,40 +149,35 @@
                                 debugging.</para></listitem>
                         </varlistentry>
                         <varlistentry>
                                 debugging.</para></listitem>
                         </varlistentry>
                         <varlistentry>

-                                <term><option>--test</option></term>
+                                <term><option>--dump-core</option></term>

 
 

-                                <listitem><para>Determine startup
-                                sequence, dump it and exit. This is an
-                                option useful for debugging
-                                only.</para></listitem>
+                                <listitem><para>Dump core on crash. This switch has no effect when run as session instance.</para></listitem>

                         </varlistentry>
                         <varlistentry>
                         </varlistentry>
                         <varlistentry>

-                                <term><option>--dump-configuration-items</option></term>
+                                <term><option>--crash-shell</option></term>

 
 

-                                <listitem><para>Dump understood unit
-                                configuration items. This outputs a
-                                terse but complete list of
-                                configuration items understood in unit
-                                definition files.</para></listitem>
+                                <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>
 
                         </varlistentry>
                         <varlistentry>
                                 <term><option>--confirm-spawn</option></term>
 

-                                <listitem><para>Ask for confirmation when spawning processes.</para></listitem>
+                                <listitem><para>Ask for confirmation when spawning processes. This switch has no effect when run as session instance.</para></listitem>

                         </varlistentry>
                         <varlistentry>
                         </varlistentry>
                         <varlistentry>

-                                <term><option>--introspect=</option></term>
+                                <term><option>--show-status</option></term>

 
 

-                                <listitem><para>Extract D-Bus
-                                interface introspection data. This is
-                                mostly useful at build at 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>
+                                <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>
                         </varlistentry>
                         <varlistentry>
                                 <term><option>--log-level=</option></term>


@@ -162,17 +195,6 @@
                                 <option>info</option>,
                                 <option>debug</option>.</para></listitem>
                         </varlistentry>
                                 <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>
 
                         <varlistentry>
                                 <term><option>--log-color=</option></term>
 


@@ -210,7 +232,7 @@
                 configuration or dynamically from system state. Units
                 may be active (meaning started, bound, plugged in, ...
                 depending on the unit type), or inactive (meaning
                 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
+                stopped, unbound, unplugged, ...), as well as in the

                 process of being activated or deactivated,
                 i.e. between the two states. The following unit types
                 are available:</para>
                 process of being activated or deactivated,
                 i.e. between the two states. The following unit types
                 are available:</para>


@@ -269,7 +291,7 @@
                         systemd. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 
                         <listitem><para>Path units may be used
                         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>
 
                         objects change or are modified. See
                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem>
 


@@ -281,7 +303,7 @@
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 
                 <para>On boot systemd activates the target unit
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</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
                 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


@@ -296,10 +318,68 @@
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                 for details about these target units.</para>
 
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                 for details about these target units.</para>
 

+                <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
+                url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink>
+                for more information about control groups, or short
+                "cgroups"). systemd uses this to effectively keep
+                track of processes. Control group information is
+                maintained in the kernel, and is accessible via the
+                file system hierarchy (beneath
+                <filename>/cgroup/systemd/</filename>), or in tools
+                such as
+                <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                (<command>ps xawf -eo pid,user,cgroup,args</command>
+                is particularly useful to list all processes and the
+                systemd units they belong to.).</para>
+
+                <para>systemd is compatible with the SysV init system
+                to a large degree: SysV init scripts are supported and
+                simply read as an alternative (though limited)
+                configuration file format. The SysV
+                <filename>/dev/initctl</filename> interface is
+                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>
+
+                <para>systemd has a minimal transaction system: if a
+                unit is requested to start up or shut down it will add
+                it and all its dependencies to a temporary
+                transaction. Then, it will verify if the transaction
+                is consistent (i.e. whether the ordering of all units
+                is cycle-free). If it is not, systemd will try to fix
+                it up, and removes non-essential jobs from the
+                transaction that might remove the loop. Also, systemd
+                tries to suppress non-essential jobs in the
+                transaction that would stop a running service. Finally
+                it is checked whether the jobs of the transaction
+                contradict jobs that have already been queued, and
+                optionally the transaction is aborted then. If all
+                worked out and the transaction is consistent and
+                minimized in its impact it is merged with all already
+                outstanding jobs and added to the run
+                queue. Effectively this means that before executing a
+                requested operation, systemd will verify that it makes
+                sense, fixing it if possible, and only failing if it
+                really cannot work.</para>
+
+                <para>Systemd contains native implementations of
+                various tasks that need to be executed as part of the
+                boot process. For example, it sets the host name or
+                configures the loopback network device. It also sets
+                up and mounts various API file systems, such as
+                <filename>/sys</filename> or
+                <filename>/proc</filename>.</para>
+

                 <para>For more information about the concepts and
                 ideas behind systemd please refer to the <ulink
                 url="http://0pointer.de/blog/projects/systemd.html">Original
                 <para>For more information about the concepts and
                 ideas behind systemd please refer to the <ulink
                 url="http://0pointer.de/blog/projects/systemd.html">Original

-                Announcement Document</ulink>.</para>
+                Design Document</ulink>.</para>

         </refsect1>
 
         <refsect1>
         </refsect1>
 
         <refsect1>


@@ -656,6 +736,87 @@
                 </variablelist>
         </refsect1>
 
                 </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>
 
         <refsect1>
                 <title>Sockets and FIFOs</title>