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diff --git a/man/systemd.xml b/man/systemd.xml index d020582b53..80591dc732 100644 --- a/man/systemd.xml +++ b/man/systemd.xml @@ -1,6 +1,6 @@ <?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"> + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. @@ -22,1269 +22,1075 @@ --> <refentry id="systemd" - xmlns:xi="http://www.w3.org/2001/XInclude"> - - <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> - <manvolnum>1</manvolnum> - </refmeta> - - <refnamediv> - <refname>systemd</refname> - <refname>init</refname> - <refpurpose>systemd system and service manager</refpurpose> - </refnamediv> - - <refsynopsisdiv> - <cmdsynopsis> - <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command> - </cmdsynopsis> - <cmdsynopsis> - <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command> - </cmdsynopsis> - </refsynopsisdiv> - - <refsect1> - <title>Description</title> - - <para>systemd is a system and service manager for - Linux operating systems. When run as first process on - boot (as PID 1), it acts as init system that brings - up and maintains userspace services.</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> - - <para>When run as a system instance, systemd interprets the - configuration file <filename>system.conf</filename> and the - files in <filename>system.conf.d</filename> directories; when - run as a user instance, systemd interprets the configuration - file <filename>user.conf</filename> and the files in - <filename>user.conf.d</filename> directories. See - <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> - for more information.</para> - </refsect1> - - <refsect1> - <title>Options</title> - - <para>The following options are understood:</para> - - <variablelist> - <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>--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>--user</option></term> - - <listitem><para>For <option>--system</option>, - tell systemd to run a - system instance, even if the process ID is - not 1, i.e. systemd is not run as init process. - <option>--user</option> does the opposite, - running a user instance even if the process - ID is 1. - 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. Note - that it is not supported booting and - maintaining a full system with systemd - running in <option>--system</option> - mode, but PID not 1. In practice, - passing <option>--system</option> explicitly is - only useful in conjunction with - <option>--test</option>.</para></listitem> - </varlistentry> - <varlistentry> - <term><option>--dump-core</option></term> - - <listitem><para>Dump core on - crash. This switch has no effect when - run as user - 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 user - 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 user - 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 user - instance. Takes a boolean argument - which may be omitted which is - interpreted as - <option>true</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>journal</option>, - <option>kmsg</option>, - <option>journal-or-kmsg</option>, - <option>null</option>.</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 project='man-pages'><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-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> - <varlistentry> - <term><option>--default-standard-output=</option></term> - <term><option>--default-standard-error=</option></term> - - <listitem><para>Sets the default - output or error output for all - services and sockets, respectively. That is, controls - the default for - <option>StandardOutput=</option> - and <option>StandardError=</option> - (see - <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> - for details). Takes one of - <option>inherit</option>, - <option>null</option>, - <option>tty</option>, - <option>journal</option>, - <option>journal+console</option>, - <option>syslog</option>, - <option>syslog+console</option>, - <option>kmsg</option>, - <option>kmsg+console</option>. If the - argument is omitted - <option>--default-standard-output=</option> - defaults to <option>journal</option> - and - <option>--default-standard-error=</option> - to - <option>inherit</option>.</para></listitem> - </varlistentry> - - <xi:include href="standard-options.xml" xpointer="help" /> - <xi:include href="standard-options.xml" xpointer="version" /> - </variablelist> - </refsect1> - - <refsect1> - <title>Concepts</title> - - <para>systemd provides a dependency system between - various entities called "units" of 12 different - types. Units encapsulate various objects that are - relevant for system boot-up 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, dynamically from system state or - programmatically at runtime. Units 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 "failed" - 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 start and control - daemons and the processes they consist of. For - details see - <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Socket units, which - encapsulate local IPC or network sockets in - the system, useful for socket-based - activation. For details about socket units see - <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - for details on socket-based activation and - other forms of activation, see - <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Target units are useful to - group units, or provide well-known - synchronization points during boot-up, see - <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Device units expose kernel - devices in systemd and may be used to - implement device-based activation. For details - see - <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Mount units control mount - points in the file system, for details see - <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Automount units provide - automount capabilities, for on-demand mounting - of file systems as well as parallelized - boot-up. See - <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Snapshot units can be used to - temporarily save the state of the set of - systemd units, which later may be restored by - activating the saved snapshot unit. For more - information see - <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 - timers. You may find details in - <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Swap units are very similar to - mount units and encapsulate memory swap - partitions or files of the operating - system. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Path units may be used - to activate other services when file system - objects change or are modified. See - <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Slice units may be used to - group units which manage system processes - (such as service and scope units) in a - hierarchical tree for resource management - purposes. See - <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - <listitem><para>Scope units are similar to - service units, but manage foreign processes - instead of starting them as well. See - <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> - - </orderedlist> - - <para>Units are named as their configuration - files. Some units have special semantics. A detailed - list is available 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 request 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 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 - <filename>graphical.target</filename> (for - fully-featured boots into the UI) or - <filename>multi-user.target</filename> (for limited - console-only boots for use in embedded or server - environments, or similar; a subset of - graphical.target). However, it is at the discretion of - the administrator to configure it as an alias to any - other target unit. See - <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="https://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>/sys/fs/cgroup/systemd/</filename>), or in tools - such as - <citerefentry project='man-pages'><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 hostname 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 - Design Document</ulink>.</para> - - <para>Note that some but not all interfaces provided - by systemd are covered by the <ulink - url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface - Stability Promise</ulink>.</para> - - <para>Units may be generated dynamically at boot and - system manager reload time, for example based on other - configuration files or parameters passed on the kernel - command line. For details see the <ulink - url="http://www.freedesktop.org/wiki/Software/systemd/Generators">Generators - Specification</ulink>.</para> - - <para>Systems which invoke systemd in a container - or initrd environment should implement the - <ulink - url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container - Interface</ulink> or <ulink - url="http://www.freedesktop.org/wiki/Software/systemd/InitrdInterface">initrd - Interface</ulink> specifications, respectively.</para> - </refsect1> - - <refsect1> - <title>Directories</title> - - <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/lib/systemd/system</filename> - and - <filename>/usr/lib/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 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. Full list of directories is provided in - <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. - </para></listitem> - </varlistentry> - </variablelist> - - <variablelist> - <varlistentry> - <term>User unit directories</term> - - <listitem><para>Similar rules apply - for the user 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=systemduserunitdir</command>. Global - configuration is done in the directory - reported by <command>pkg-config - systemd - --variable=systemduserconfdir</command>. The - <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 - units. Full list of directories is provided in - <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. - </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 cannot be started by activating it - in the SysV runlevel link - farm.</para></listitem> - </varlistentry> - </variablelist> - </refsect1> - - <refsect1> - <title>Signals</title> - - <variablelist> - <varlistentry> - <term><constant>SIGTERM</constant></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 user managers will - start the - <filename>exit.target</filename> unit - when this signal is received. This is - mostly equivalent to - <command>systemctl --user start - exit.target</command>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGINT</constant></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>. If this - signal is received more often than 7 - times per 2s an immediate reboot is - triggered. Note that pressing - Ctrl-Alt-Del on the console will - trigger this signal. Hence, if a - reboot is hanging pressing - Ctrl-Alt-Del more than 7 times in 2s - is a relatively safe way to trigger an - immediate reboot.</para> - - <para>systemd user managers - treat this signal the same way as - <constant>SIGTERM</constant>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGWINCH</constant></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 user - managers.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGPWR</constant></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><constant>SIGUSR1</constant></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><constant>SIGUSR2</constant></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>systemd-analyze - dump</command>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGHUP</constant></term> - - <listitem><para>Reloads the complete - daemon configuration. This is mostly - equivalent to <command>systemctl - daemon-reload</command>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+0</constant></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><constant>SIGRTMIN+1</constant></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> - - <varlistentry> - <term><constant>SIGRTMIN+2</constant></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><constant>SIGRTMIN+3</constant></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><constant>SIGRTMIN+4</constant></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><constant>SIGRTMIN+5</constant></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> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+6</constant></term> - - <listitem><para>Reboots the machine via kexec, - starts the - <filename>kexec.target</filename> - unit. This is mostly equivalent to - <command>systemctl start - kexec.target</command>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+13</constant></term> - - <listitem><para>Immediately halts the machine.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+14</constant></term> - - <listitem><para>Immediately powers off the machine.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+15</constant></term> - - <listitem><para>Immediately reboots the machine.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+16</constant></term> - - <listitem><para>Immediately reboots the machine with kexec.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+20</constant></term> - - <listitem><para>Enables display of - status messages on the console, as - controlled via - <varname>systemd.show_status=1</varname> - on the kernel command - line.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+21</constant></term> - - <listitem><para>Disables display of - status messages on the console, as - controlled via - <varname>systemd.show_status=0</varname> - on the kernel command - line.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+22</constant></term> - <term><constant>SIGRTMIN+23</constant></term> - - <listitem><para>Sets the log level to - <literal>debug</literal> - (or <literal>info</literal> on - <constant>SIGRTMIN+23</constant>), as - controlled via - <varname>systemd.log_level=debug</varname> - (or <varname>systemd.log_level=info</varname> - on <constant>SIGRTMIN+23</constant>) on - the kernel command - line.</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+24</constant></term> - - <listitem><para>Immediately exits the - manager (only available for --user - instances).</para></listitem> - </varlistentry> - - <varlistentry> - <term><constant>SIGRTMIN+26</constant></term> - <term><constant>SIGRTMIN+27</constant></term> - <term><constant>SIGRTMIN+28</constant></term> - - <listitem><para>Sets the log level to - <literal>journal-or-kmsg</literal> (or - <literal>console</literal> on - <constant>SIGRTMIN+27</constant>, - <literal>kmsg</literal> on - <constant>SIGRTMIN+28</constant>), as - controlled via - <varname>systemd.log_target=journal-or-kmsg</varname> - (or - <varname>systemd.log_target=console</varname> - on <constant>SIGRTMIN+27</constant> or - <varname>systemd.log_target=kmsg</varname> - on <constant>SIGRTMIN+28</constant>) - on the kernel command - line.</para></listitem> - </varlistentry> - </variablelist> - </refsect1> - - <refsect1> - <title>Environment</title> - - <variablelist class='environment-variables'> - <varlistentry> - <term><varname>$SYSTEMD_LOG_LEVEL</varname></term> - <listitem><para>systemd reads the - log level from this environment - variable. This can be overridden with - <option>--log-level=</option>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>$SYSTEMD_LOG_TARGET</varname></term> - <listitem><para>systemd reads the - log target from this environment - variable. This can be overridden with - <option>--log-target=</option>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>$SYSTEMD_LOG_COLOR</varname></term> - <listitem><para>Controls whether - systemd highlights important log - messages. This can be overridden with - <option>--log-color=</option>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>$SYSTEMD_LOG_LOCATION</varname></term> - <listitem><para>Controls whether - systemd prints the code location along - with log messages. This can be - overridden 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 user - 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> - - <refsect1> - <title>Kernel Command Line</title> - - <para>When run as system instance systemd parses a - number of kernel command line - arguments<footnote><para>If run inside a Linux - container these arguments may be passed as command - line arguments to systemd itself, next to any of the - command line options listed in the Options section - above. If run outside of Linux containers, these - arguments are parsed from - <filename>/proc/cmdline</filename> - instead.</para></footnote>:</para> - - <variablelist class='kernel-commandline-options'> - <varlistentry> - <term><varname>systemd.unit=</varname></term> - <term><varname>rd.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. The - option prefixed with - <literal>rd.</literal> is honored - only in the initial RAM disk (initrd), - while the one that is not prefixed only - in the main system.</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 shell is - spawned. 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 - <constant>-1</constant>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>systemd.confirm_spawn=</varname></term> - - <listitem><para>Takes a boolean - argument. If <option>true</option>, - asks for confirmation when spawning - processes. Defaults to - <option>false</option>.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>systemd.show_status=</varname></term> - - <listitem><para>Takes a boolean - argument or the constant - <constant>auto</constant>. If - <option>true</option>, shows terse - service status updates on the console - during bootup. - <constant>auto</constant> behaves like - <option>false</option> until a service - fails or there is a significant delay - in boot. Defaults to - <option>true</option>, unless - <option>quiet</option> is passed as - kernel command line option in which - case it defaults to - <constant>auto</constant>.</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.default_standard_output=</varname></term> - <term><varname>systemd.default_standard_error=</varname></term> - <listitem><para>Controls default - standard output and error output for - services, with the same effect as the - <option>--default-standard-output=</option> - and <option>--default-standard-error=</option> - command line arguments described - above, respectively.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>systemd.setenv=</varname></term> - - <listitem><para>Takes a string - argument in the form VARIABLE=VALUE. - May be used to set default environment - variables to add to forked child processes. - May be used more than once to set multiple - variables.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>quiet</varname></term> - - <listitem><para>Turn off - status output at boot, much like - <varname>systemd.show_status=false</varname> - would. Note that this option is also - read by the kernel itself and disables - kernel log output. Passing this option - hence turns off the usual output from - both the system manager and the kernel. - </para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>debug</varname></term> - - <listitem><para>Turn on debugging - output. This is equivalent to - <varname>systemd.log_level=debug</varname>. - Note that this option is also read by - the kernel itself and enables kernel - debug output. Passing this option - hence turns on the debug output from - both the system manager and the - kernel.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>emergency</varname></term> - <term><varname>-b</varname></term> - - <listitem><para>Boot into emergency - mode. This is equivalent to - <varname>systemd.unit=emergency.target</varname> - and provided for compatibility reasons - and to be easier to - type.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>rescue</varname></term> - <term><varname>single</varname></term> - <term><varname>s</varname></term> - <term><varname>S</varname></term> - <term><varname>1</varname></term> - - <listitem><para>Boot into rescue - mode. This is equivalent to - <varname>systemd.unit=rescue.target</varname> - and provided for compatibility reasons - and to be easier to - type.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>2</varname></term> - <term><varname>3</varname></term> - <term><varname>4</varname></term> - <term><varname>5</varname></term> - - <listitem><para>Boot into the - specified legacy SysV runlevel. These - are equivalent to - <varname>systemd.unit=runlevel2.target</varname>, - <varname>systemd.unit=runlevel3.target</varname>, - <varname>systemd.unit=runlevel4.target</varname>, - and <varname>systemd.unit=runlevel5.target</varname>, respectively, - and provided for compatibility reasons - and to be easier to - type.</para></listitem> - </varlistentry> - - <varlistentry> - <term><varname>locale.LANG=</varname></term> - <term><varname>locale.LANGUAGE=</varname></term> - <term><varname>locale.LC_CTYPE=</varname></term> - <term><varname>locale.LC_NUMERIC=</varname></term> - <term><varname>locale.LC_TIME=</varname></term> - <term><varname>locale.LC_COLLATE=</varname></term> - <term><varname>locale.LC_MONETARY=</varname></term> - <term><varname>locale.LC_MESSAGES=</varname></term> - <term><varname>locale.LC_PAPER=</varname></term> - <term><varname>locale.LC_NAME=</varname></term> - <term><varname>locale.LC_ADDRESS=</varname></term> - <term><varname>locale.LC_TELEPHONE=</varname></term> - <term><varname>locale.LC_MEASUREMENT=</varname></term> - <term><varname>locale.LC_IDENTIFICATION=</varname></term> - - <listitem><para>Set the system locale - to use. This overrides the settings in - <filename>/etc/locale.conf</filename>. For - more information see - <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> - and - <citerefentry><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>. - </para></listitem> - </varlistentry> - </variablelist> - - <para>For other kernel command line parameters - understood by components of the core OS, please refer - to - <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> - </refsect1> - - <refsect1> - <title>Sockets and FIFOs</title> - - <variablelist> - <varlistentry> - <term><filename>/run/systemd/notify</filename></term> - - <listitem><para>Daemon status - notification socket. This is an - <constant>AF_UNIX</constant> datagram socket 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>/run/systemd/shutdownd</filename></term> - - <listitem><para>Used internally by the - <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry> - tool to implement delayed - shutdowns. This is an <constant>AF_UNIX</constant> datagram - socket.</para></listitem> - </varlistentry> - - <varlistentry> - <term><filename>/run/systemd/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 - <constant>AF_UNIX</constant> stream socket. 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> - </refsect1> - - <refsect1> - <title>See Also</title> - <para> - The <ulink url="http://www.freedesktop.org/wiki/Software/systemd/">systemd Homepage</ulink>, - <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, - <citerefentry><refentrytitle>journalctl</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>3</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>, - <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>, - <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>, - <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>, - <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> - </para> - </refsect1> + xmlns:xi="http://www.w3.org/2001/XInclude"> + + <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> + <manvolnum>1</manvolnum> + </refmeta> + + <refnamediv> + <refname>systemd</refname> + <refname>init</refname> + <refpurpose>systemd system and service manager</refpurpose> + </refnamediv> + + <refsynopsisdiv> + <cmdsynopsis> + <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command> + </cmdsynopsis> + <cmdsynopsis> + <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command> + </cmdsynopsis> + </refsynopsisdiv> + + <refsect1> + <title>Description</title> + + <para>systemd is a system and service manager for Linux operating + systems. When run as first process on boot (as PID 1), it acts as + init system that brings up and maintains userspace + services.</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> + + <para>When run as a system instance, systemd interprets the + configuration file <filename>system.conf</filename> and the files + in <filename>system.conf.d</filename> directories; when run as a + user instance, systemd interprets the configuration file + <filename>user.conf</filename> and the files in + <filename>user.conf.d</filename> directories. See + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for more information.</para> + </refsect1> + + <refsect1> + <title>Options</title> + + <para>The following options are understood:</para> + + <variablelist> + <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>--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>--user</option></term> + + <listitem><para>For <option>--system</option>, tell systemd to + run a system instance, even if the process ID is not 1, i.e. + systemd is not run as init process. <option>--user</option> + does the opposite, running a user instance even if the process + ID is 1. 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. Note that it is not supported booting and + maintaining a full system with systemd running in + <option>--system</option> mode, but PID not 1. In practice, + passing <option>--system</option> explicitly is only useful in + conjunction with <option>--test</option>.</para></listitem> + </varlistentry> + <varlistentry> + <term><option>--dump-core</option></term> + + <listitem><para>Dump core on crash. This switch has no effect + when run as user 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 user + 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 user + 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 user instance. + Takes a boolean argument which may be omitted which is + interpreted as <option>true</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>journal</option>, + <option>kmsg</option>, + <option>journal-or-kmsg</option>, + <option>null</option>.</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 project='man-pages'><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-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> + <varlistentry> + <term><option>--default-standard-output=</option></term> + <term><option>--default-standard-error=</option></term> + + <listitem><para>Sets the default output or error output for + all services and sockets, respectively. That is, controls the + default for <option>StandardOutput=</option> and + <option>StandardError=</option> (see + <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry> + for details). Takes one of + <option>inherit</option>, + <option>null</option>, + <option>tty</option>, + <option>journal</option>, + <option>journal+console</option>, + <option>syslog</option>, + <option>syslog+console</option>, + <option>kmsg</option>, + <option>kmsg+console</option>. If the + argument is omitted + <option>--default-standard-output=</option> defaults to + <option>journal</option> and + <option>--default-standard-error=</option> to + <option>inherit</option>.</para></listitem> + </varlistentry> + + <xi:include href="standard-options.xml" xpointer="help" /> + <xi:include href="standard-options.xml" xpointer="version" /> + </variablelist> + </refsect1> + + <refsect1> + <title>Concepts</title> + + <para>systemd provides a dependency system between various + entities called "units" of 12 different types. Units encapsulate + various objects that are relevant for system boot-up 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, + dynamically from system state or programmatically at runtime. + Units 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 + "failed" 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 start and control daemons + and the processes they consist of. For details see + <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Socket units, which encapsulate local IPC or + network sockets in the system, useful for socket-based + activation. For details about socket units see + <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + for details on socket-based activation and other forms of + activation, see + <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Target units are useful to group units, or + provide well-known synchronization points during boot-up, see + <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Device units expose kernel devices in systemd + and may be used to implement device-based activation. For + details see + <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Mount units control mount points in the file + system, for details see + <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Automount units provide automount capabilities, + for on-demand mounting of file systems as well as parallelized + boot-up. See + <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Snapshot units can be used to temporarily save + the state of the set of systemd units, which later may be + restored by activating the saved snapshot unit. For more + information see + <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 timers. You may find details in + <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Swap units are very similar to mount units and + encapsulate memory swap partitions or files of the operating + system. They are described in + <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Path units may be used to activate other + services when file system objects change or are modified. See + <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Slice units may be used to group units which + manage system processes (such as service and scope units) in a + hierarchical tree for resource management purposes. See + <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + <listitem><para>Scope units are similar to service units, but + manage foreign processes instead of starting them as well. See + <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> + + </orderedlist> + + <para>Units are named as their configuration files. Some units + have special semantics. A detailed list is available 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 + request 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 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 <filename>graphical.target</filename> (for fully-featured + boots into the UI) or <filename>multi-user.target</filename> (for + limited console-only boots for use in embedded or server + environments, or similar; a subset of graphical.target). However, + it is at the discretion of the administrator to configure it as an + alias to any other target unit. See + <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="https://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>/sys/fs/cgroup/systemd/</filename>), or in tools such as + <citerefentry project='man-pages'><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 hostname 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 Design Document</ulink>.</para> + + <para>Note that some but not all interfaces provided + by systemd are covered by the + <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface + Stability Promise</ulink>.</para> + + <para>Units may be generated dynamically at boot and system + manager reload time, for example based on other configuration + files or parameters passed on the kernel command line. For details + see the + <ulink url="http://www.freedesktop.org/wiki/Software/systemd/Generators">Generators Specification</ulink>.</para> + + <para>Systems which invoke systemd in a container or initrd + environment should implement the + <ulink url="http://www.freedesktop.org/wiki/Software/systemd/ContainerInterface">Container Interface</ulink> or + <ulink url="http://www.freedesktop.org/wiki/Software/systemd/InitrdInterface">initrd Interface</ulink> + specifications, respectively.</para> + </refsect1> + + <refsect1> + <title>Directories</title> + + <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/lib/systemd/system</filename> + and <filename>/usr/lib/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 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. Full list of directories is provided in + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </para></listitem> + </varlistentry> + </variablelist> + + <variablelist> + <varlistentry> + <term>User unit directories</term> + + <listitem><para>Similar rules apply for the user 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=systemduserunitdir</command>. Global configuration + is done in the directory reported by <command>pkg-config + systemd --variable=systemduserconfdir</command>. The + <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 units. Full list of + directories is provided in + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. + </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 cannot be started by activating it in the + SysV runlevel link farm.</para></listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Signals</title> + + <variablelist> + <varlistentry> + <term><constant>SIGTERM</constant></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 user managers will start the + <filename>exit.target</filename> unit when this signal is + received. This is mostly equivalent to <command>systemctl + --user start exit.target</command>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGINT</constant></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>. If this signal is received more + often than 7 times per 2s an immediate reboot is triggered. + Note that pressing Ctrl-Alt-Del on the console will trigger + this signal. Hence, if a reboot is hanging pressing + Ctrl-Alt-Del more than 7 times in 2s is a relatively safe way + to trigger an immediate reboot.</para> + + <para>systemd user managers treat this signal the same way as + <constant>SIGTERM</constant>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGWINCH</constant></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 user + managers.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGPWR</constant></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><constant>SIGUSR1</constant></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><constant>SIGUSR2</constant></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>systemd-analyze dump</command>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGHUP</constant></term> + + <listitem><para>Reloads the complete daemon configuration. + This is mostly equivalent to <command>systemctl + daemon-reload</command>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+0</constant></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><constant>SIGRTMIN+1</constant></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> + + <varlistentry> + <term><constant>SIGRTMIN+2</constant></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><constant>SIGRTMIN+3</constant></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><constant>SIGRTMIN+4</constant></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><constant>SIGRTMIN+5</constant></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> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+6</constant></term> + + <listitem><para>Reboots the machine via kexec, starts the + <filename>kexec.target</filename> unit. This is mostly + equivalent to <command>systemctl start + kexec.target</command>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+13</constant></term> + + <listitem><para>Immediately halts the machine.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+14</constant></term> + + <listitem><para>Immediately powers off the machine.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+15</constant></term> + + <listitem><para>Immediately reboots the machine.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+16</constant></term> + + <listitem><para>Immediately reboots the machine with kexec.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+20</constant></term> + + <listitem><para>Enables display of status messages on the + console, as controlled via + <varname>systemd.show_status=1</varname> on the kernel command + line.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+21</constant></term> + + <listitem><para>Disables display of + status messages on the console, as + controlled via + <varname>systemd.show_status=0</varname> + on the kernel command + line.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+22</constant></term> + <term><constant>SIGRTMIN+23</constant></term> + + <listitem><para>Sets the log level to <literal>debug</literal> + (or <literal>info</literal> on + <constant>SIGRTMIN+23</constant>), as controlled via + <varname>systemd.log_level=debug</varname> (or + <varname>systemd.log_level=info</varname> on + <constant>SIGRTMIN+23</constant>) on the kernel command + line.</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+24</constant></term> + + <listitem><para>Immediately exits the manager (only available + for --user instances).</para></listitem> + </varlistentry> + + <varlistentry> + <term><constant>SIGRTMIN+26</constant></term> + <term><constant>SIGRTMIN+27</constant></term> + <term><constant>SIGRTMIN+28</constant></term> + + <listitem><para>Sets the log level to + <literal>journal-or-kmsg</literal> (or + <literal>console</literal> on + <constant>SIGRTMIN+27</constant>, <literal>kmsg</literal> on + <constant>SIGRTMIN+28</constant>), as controlled via + <varname>systemd.log_target=journal-or-kmsg</varname> (or + <varname>systemd.log_target=console</varname> on + <constant>SIGRTMIN+27</constant> or + <varname>systemd.log_target=kmsg</varname> on + <constant>SIGRTMIN+28</constant>) on the kernel command + line.</para></listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Environment</title> + + <variablelist class='environment-variables'> + <varlistentry> + <term><varname>$SYSTEMD_LOG_LEVEL</varname></term> + <listitem><para>systemd reads the log level from this + environment variable. This can be overridden with + <option>--log-level=</option>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>$SYSTEMD_LOG_TARGET</varname></term> + <listitem><para>systemd reads the log target from this + environment variable. This can be overridden with + <option>--log-target=</option>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>$SYSTEMD_LOG_COLOR</varname></term> + <listitem><para>Controls whether systemd highlights important + log messages. This can be overridden with + <option>--log-color=</option>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>$SYSTEMD_LOG_LOCATION</varname></term> + <listitem><para>Controls whether systemd prints the code + location along with log messages. This can be overridden 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 user 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> + + <refsect1> + <title>Kernel Command Line</title> + + <para>When run as system instance systemd parses a number of + kernel command line arguments<footnote><para>If run inside a Linux + container these arguments may be passed as command line arguments + to systemd itself, next to any of the command line options listed + in the Options section above. If run outside of Linux containers, + these arguments are parsed from <filename>/proc/cmdline</filename> + instead.</para></footnote>:</para> + + <variablelist class='kernel-commandline-options'> + <varlistentry> + <term><varname>systemd.unit=</varname></term> + <term><varname>rd.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. The option prefixed with + <literal>rd.</literal> is honored only in the initial RAM disk + (initrd), while the one that is not prefixed only in the main + system.</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 shell is spawned. 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 <constant>-1</constant>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>systemd.confirm_spawn=</varname></term> + + <listitem><para>Takes a boolean argument. If + <option>true</option>, asks for confirmation when spawning + processes. Defaults to + <option>false</option>.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>systemd.show_status=</varname></term> + + <listitem><para>Takes a boolean argument or the constant + <constant>auto</constant>. If <option>true</option>, shows + terse service status updates on the console during bootup. + <constant>auto</constant> behaves like <option>false</option> + until a service fails or there is a significant delay in boot. + Defaults to <option>true</option>, unless + <option>quiet</option> is passed as kernel command line option + in which case it defaults to + <constant>auto</constant>.</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.default_standard_output=</varname></term> + <term><varname>systemd.default_standard_error=</varname></term> + <listitem><para>Controls default standard output and error + output for services, with the same effect as the + <option>--default-standard-output=</option> and + <option>--default-standard-error=</option> command line + arguments described above, respectively.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>systemd.setenv=</varname></term> + + <listitem><para>Takes a string argument in the form + VARIABLE=VALUE. May be used to set default environment + variables to add to forked child processes. May be used more + than once to set multiple variables.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>quiet</varname></term> + + <listitem><para>Turn off status output at boot, much like + <varname>systemd.show_status=false</varname> would. Note that + this option is also read by the kernel itself and disables + kernel log output. Passing this option hence turns off the + usual output from both the system manager and the kernel. + </para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>debug</varname></term> + + <listitem><para>Turn on debugging output. This is equivalent + to <varname>systemd.log_level=debug</varname>. Note that this + option is also read by the kernel itself and enables kernel + debug output. Passing this option hence turns on the debug + output from both the system manager and the + kernel.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>emergency</varname></term> + <term><varname>-b</varname></term> + + <listitem><para>Boot into emergency mode. This is equivalent + to <varname>systemd.unit=emergency.target</varname> and + provided for compatibility reasons and to be easier to + type.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>rescue</varname></term> + <term><varname>single</varname></term> + <term><varname>s</varname></term> + <term><varname>S</varname></term> + <term><varname>1</varname></term> + + <listitem><para>Boot into rescue mode. This is equivalent to + <varname>systemd.unit=rescue.target</varname> and provided for + compatibility reasons and to be easier to + type.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>2</varname></term> + <term><varname>3</varname></term> + <term><varname>4</varname></term> + <term><varname>5</varname></term> + + <listitem><para>Boot into the specified legacy SysV runlevel. + These are equivalent to + <varname>systemd.unit=runlevel2.target</varname>, + <varname>systemd.unit=runlevel3.target</varname>, + <varname>systemd.unit=runlevel4.target</varname>, and + <varname>systemd.unit=runlevel5.target</varname>, + respectively, and provided for compatibility reasons and to be + easier to type.</para></listitem> + </varlistentry> + + <varlistentry> + <term><varname>locale.LANG=</varname></term> + <term><varname>locale.LANGUAGE=</varname></term> + <term><varname>locale.LC_CTYPE=</varname></term> + <term><varname>locale.LC_NUMERIC=</varname></term> + <term><varname>locale.LC_TIME=</varname></term> + <term><varname>locale.LC_COLLATE=</varname></term> + <term><varname>locale.LC_MONETARY=</varname></term> + <term><varname>locale.LC_MESSAGES=</varname></term> + <term><varname>locale.LC_PAPER=</varname></term> + <term><varname>locale.LC_NAME=</varname></term> + <term><varname>locale.LC_ADDRESS=</varname></term> + <term><varname>locale.LC_TELEPHONE=</varname></term> + <term><varname>locale.LC_MEASUREMENT=</varname></term> + <term><varname>locale.LC_IDENTIFICATION=</varname></term> + + <listitem><para>Set the system locale to use. This overrides + the settings in <filename>/etc/locale.conf</filename>. For + more information see + <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> + and + <citerefentry><refentrytitle>locale</refentrytitle><manvolnum>7</manvolnum></citerefentry>. + </para></listitem> + </varlistentry> + </variablelist> + + <para>For other kernel command line parameters understood by + components of the core OS, please refer to + <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> + </refsect1> + + <refsect1> + <title>Sockets and FIFOs</title> + + <variablelist> + <varlistentry> + <term><filename>/run/systemd/notify</filename></term> + + <listitem><para>Daemon status notification socket. This is an + <constant>AF_UNIX</constant> datagram socket 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>/run/systemd/shutdownd</filename></term> + + <listitem><para>Used internally by the + <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry> + tool to implement delayed shutdowns. This is an + <constant>AF_UNIX</constant> datagram + socket.</para></listitem> + </varlistentry> + + <varlistentry> + <term><filename>/run/systemd/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 + <constant>AF_UNIX</constant> stream socket. 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> + </refsect1> + + <refsect1> + <title>See Also</title> + <para> + The <ulink url="http://www.freedesktop.org/wiki/Software/systemd/">systemd Homepage</ulink>, + <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>journalctl</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>3</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>, + <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>, + <citerefentry><refentrytitle>kernel-command-line</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>, + <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry> + </para> + </refsect1> </refentry> |