manager: when breaking ordering cycle show full cycle loop

[elogind.git] / man / systemd.xml

diff --git a/man/systemd.xml b/man/systemd.xml
index 007705e4943ebaa296505c8e2195d2834be4747c..d2112b1bf02963d7d7f725f56e3fb56ff302816d 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>


@@ -88,28 +95,6 @@
                                 <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>--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>
 
                         <varlistentry>
                                 <term><option>--test</option></term>
 


@@ -127,17 +112,12 @@
                                 configuration items understood in unit
                                 definition files.</para></listitem>
                         </varlistentry>
                                 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
                         <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
                                 to generate data suitable for the
                                 D-Bus interfaces
                                 repository. Optionally the interface


@@ -146,6 +126,61 @@
                                 introspection data for all interfaces
                                 is dumped.</para></listitem>
                         </varlistentry>
                                 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>
 
                         <varlistentry>
                                 <term><option>--log-level=</option></term>
 


@@ -162,17 +197,6 @@
                                 <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>
 


@@ -202,18 +226,29 @@
                 <para>systemd provides a dependency system between
                 various entities called "units". Units encapsulate
                 various objects that are relevant for system boot-up
                 <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
                 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
 
                 <orderedlist>
                         <listitem><para>Service units, which control


@@ -256,7 +291,7 @@
                         systemd units, which later may be restored by
                         activating the saved snapshot unit. For more
                         information see
                         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
 
                         <listitem><para>Timer units are useful for
                         triggering activation of other units based on


@@ -269,7 +304,7 @@
                         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>
 


@@ -280,8 +315,37 @@
                 list you may find in
                 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 
                 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
                 <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 +360,68 @@
                 <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>


@@ -326,9 +448,12 @@
                                 --variable=systemdsystemconfdir</command>
                                 returns the path of the system
                                 configuration directory. Packages
                                 --variable=systemdsystemconfdir</command>
                                 returns the path of the system
                                 configuration directory. Packages

-                                should alter the content of these directories
-                                only with the
-                                <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                                should alter the content of these
+                                directories only with the
+                                <command>enable</command> and
+                                <command>disable</command> commands of
+                                the
+                                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>

                                 tool.</para></listitem>
                         </varlistentry>
                 </variablelist>
                                 tool.</para></listitem>
                         </varlistentry>
                 </variablelist>


@@ -347,11 +472,14 @@
                                 unit files in the directory returned
                                 by <command>pkg-config systemd
                                 --variable=systemdsessionunitdir</command>. Global
                                 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
+                                configuration is done in the directory
+                                reported by <command>pkg-config
+                                systemd

                                 --variable=systemdsessionconfdir</command>. The
                                 --variable=systemdsessionconfdir</command>. The

-                                <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+                                <command>enable</command> and
+                                <command>disable</command> commands of
+                                the
+                                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>

                                 tool can handle both global (i.e. for
                                 all users) and private (for one user)
                                 enabling/disabling of
                                 tool can handle both global (i.e. for
                                 all users) and private (for one user)
                                 enabling/disabling of


@@ -386,7 +514,7 @@
                                 when figuring out whether a service
                                 shall be enabled. Note that a service
                                 unit with a native unit configuration
                                 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>
                                 in the SysV runlevel link
                                 farm.</para></listitem>
                         </varlistentry>


@@ -656,6 +784,87 @@
                 </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>
 


@@ -720,7 +929,6 @@
                 <para>
                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                 <para>
                         <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>,
                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                         <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>,