mirror of
https://github.com/systemd/systemd.git
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463aef23a7
Before this patch, there was no way to request all running user instances for reexecuting. However this can be useful especially during package updates otherwise user instances are never updated and keep running a potentially very old version of the binaries. Now assuming that we have enough priviledge, it's possible to request reexecution of all user instances: systemctl kill --signal=SIGRTMIN+25 "user@*.service" Note that this request is obviously asynchronous as it relies on a signal. Keeping "systemctl kill" as the only interface should be good enough to make this obvious and that's the reason why another interface, such as "systemctl --global daemon-reexec" has not been considered. PID1 already uses SIGTERM for reexecuting hence sending it SIGRTMIN+25 is a nop.
1290 lines
62 KiB
XML
1290 lines
62 KiB
XML
<?xml version='1.0'?>
|
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
|
||
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
|
||
|
||
<refentry id="systemd"
|
||
xmlns:xi="http://www.w3.org/2001/XInclude">
|
||
|
||
<refentryinfo>
|
||
<title>systemd</title>
|
||
<productname>systemd</productname>
|
||
</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>/usr/lib/systemd/systemd</command>
|
||
<arg choice="opt" rep="repeat">OPTIONS</arg>
|
||
</cmdsynopsis>
|
||
<cmdsynopsis>
|
||
<command>init</command>
|
||
<arg choice="opt" rep="repeat">OPTIONS</arg>
|
||
<arg choice="req">COMMAND</arg>
|
||
</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. Separate
|
||
instances are started for logged-in users to start their services.</para>
|
||
|
||
<para><command>systemd</command> is usually not invoked directly by the user, but is installed as the
|
||
<filename>/sbin/init</filename> symlink and started during early boot. The user manager instances are
|
||
started automatically through the
|
||
<citerefentry><refentrytitle>user@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
service.</para>
|
||
|
||
<para>For compatibility with SysV, if the binary is called as <command>init</command> and is not the
|
||
first process on the machine (PID 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
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||
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>Concepts</title>
|
||
|
||
<para>systemd provides a dependency system between various
|
||
entities called "units" of 11 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
|
||
files, 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, an operation
|
||
timed out, or after too many restarts). 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>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.
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||
<varname>Requires=</varname> and <varname>Conflicts=</varname>) as
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||
well as ordering dependencies (<varname>After=</varname> and
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||
<varname>Before=</varname>). NB: ordering and requirement
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||
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,
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||
they will be started in parallel. It is a common pattern that both
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||
requirement and ordering dependencies are placed between two
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||
units. Also note that the majority of dependencies are implicitly
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||
created and maintained by systemd. In most cases, it should be
|
||
unnecessary to declare additional dependencies manually, however
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||
it is possible to do this.</para>
|
||
|
||
<para>Application programs and units (via dependencies) may
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||
request state changes of units. In systemd, these requests are
|
||
encapsulated as 'jobs' and maintained in a job queue. Jobs may
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||
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>systemd only keeps a minimal set of units loaded into memory. Specifically, the only units that are kept
|
||
loaded into memory are those for which at least one of the following conditions is true:</para>
|
||
|
||
<orderedlist>
|
||
<listitem><para>It is in an active, activating, deactivating or failed state (i.e. in any unit state except for <literal>inactive</literal>)</para></listitem>
|
||
<listitem><para>It has a job queued for it</para></listitem>
|
||
<listitem><para>It is a dependency of at least one other unit that is loaded into memory</para></listitem>
|
||
<listitem><para>It has some form of resource still allocated (e.g. a service unit that is inactive but for which
|
||
a process is still lingering that ignored the request to be terminated)</para></listitem>
|
||
<listitem><para>It has been pinned into memory programmatically by a D-Bus call</para></listitem>
|
||
</orderedlist>
|
||
|
||
<para>systemd will automatically and implicitly load units from disk — if they are not loaded yet — as soon as
|
||
operations are requested for them. Thus, in many respects, the fact whether a unit is loaded or not is invisible to
|
||
clients. Use <command>systemctl list-units --all</command> to comprehensively list all units currently loaded. Any
|
||
unit for which none of the conditions above applies is promptly unloaded. Note that when a unit is unloaded from
|
||
memory its accounting data is flushed out too. However, this data is generally not lost, as a journal log record
|
||
is generated declaring the consumed resources whenever a unit shuts down.</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/cgroup-v1/cgroups.txt">cgroups.txt</ulink>
|
||
for more information about control groups, or short "cgroups").
|
||
systemd uses this to effectively keep track of processes. Control
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||
group information is maintained in the kernel, and is accessible
|
||
via the file system hierarchy (beneath
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||
<filename>/sys/fs/cgroup/systemd/</filename>), or in tools such as
|
||
<citerefentry project='man-pages'><refentrytitle>systemd-cgls</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
or
|
||
<citerefentry project='man-pages'><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
||
(<command>ps xawf -eo pid,user,cgroup,args</command> is
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||
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
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||
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>Note that transactions are generated independently of a unit's
|
||
state at runtime, hence, for example, if a start job is requested on an
|
||
already started unit, it will still generate a transaction and wake up any
|
||
inactive dependencies (and cause propagation of other jobs as per the
|
||
defined relationships). This is because the enqueued job is at the time of
|
||
execution compared to the target unit's state and is marked successful and
|
||
complete when both satisfy. However, this job also pulls in other
|
||
dependencies due to the defined relationships and thus leads to, in our
|
||
example, start jobs for any of those inactive units getting queued as
|
||
well.</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="https://systemd.io/PORTABILITY_AND_STABILITY/">Interface Portability and 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
|
||
<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
|
||
|
||
<para>The D-Bus API of <command>systemd</command> is described in
|
||
<citerefentry><refentrytitle>org.freedesktop.systemd1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>org.freedesktop.LogControl1</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para>
|
||
|
||
<para>Systems which invoke systemd in a container or initrd environment should implement the <ulink
|
||
url="https://systemd.io/CONTAINER_INTERFACE">Container Interface</ulink> or
|
||
<ulink url="https://systemd.io/INITRD_INTERFACE/">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
|
||
--job-mode=replace-irreversibly</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 ctrl-alt-del.target --job-mode=replace-irreversibly</command>. If
|
||
this signal is received more than 7 times per 2s, an immediate reboot is triggered. Note
|
||
that pressing
|
||
<keycombo><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Del</keycap></keycombo> on the
|
||
console will trigger this signal. Hence, if a reboot is hanging, pressing
|
||
<keycombo><keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Del</keycap></keycombo> more than
|
||
7 times in 2 seconds 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 isolate
|
||
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
|
||
--job-mode=replace-irreversibly</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
|
||
--job-mode=replace-irreversibly</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
|
||
--job-mode=replace-irreversibly</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
|
||
--job-mode=replace-irreversibly</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>
|
||
|
||
<listitem><para>Sets the service manager's log level to <literal>debug</literal>, in a fashion equivalent to
|
||
<varname>systemd.log_level=debug</varname> on the kernel command line.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>SIGRTMIN+23</constant></term>
|
||
|
||
<listitem><para>Restores the log level to its configured value. The configured value is derived from – in order
|
||
of priority – the value specified with <varname>systemd.log-level=</varname> on the kernel command line, or the
|
||
value specified with <option>LogLevel=</option> in the configuration file, or the built-in default of
|
||
<literal>info</literal>.</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+25</constant></term>
|
||
|
||
<listitem><para>Upon receiving this signal the systemd manager will reexecute itself. This
|
||
is mostly equivalent to <command>systemctl daemon-reexec</command> except that it will be
|
||
done asynchronously.</para>
|
||
|
||
<para>The systemd system manager treats this signal the same way as
|
||
<constant>SIGTERM</constant>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>SIGRTMIN+26</constant></term>
|
||
|
||
<listitem><para>Restores the log target to its configured value. The configured value is derived from – in
|
||
order of priority – the value specified with <varname>systemd.log-target=</varname> on the kernel command line,
|
||
or the value specified with <option>LogTarget=</option> in the configuration file, or the built-in
|
||
default.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><constant>SIGRTMIN+27</constant></term>
|
||
<term><constant>SIGRTMIN+28</constant></term>
|
||
|
||
<listitem><para>Sets the log target to <literal>console</literal> on <constant>SIGRTMIN+27</constant> (or
|
||
<literal>kmsg</literal> on <constant>SIGRTMIN+28</constant>), in a fashion equivalent to
|
||
<varname>systemd.log_target=console</varname> (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>
|
||
|
||
<para>The environment block for the system manager is initially set by the kernel. (In particular,
|
||
<literal>key=value</literal> assignments on the kernel command line are returned into environment
|
||
variables for PID 1). For the user manager, the system manager sets the environment as described in the
|
||
"Environment Variables in Spawned Processes" section of
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
|
||
<varname>DefaultEnvironment=</varname> setting in the system manager applies to all services including
|
||
<filename>user@.service</filename>. Additional entries may be configured (as for any other service)
|
||
through the <varname>Environment=</varname> and <varname>EnvironmentFile=</varname> settings for
|
||
<filename>user@.service</filename> (see
|
||
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>). Also,
|
||
additional environment variables may be set through the <varname>ManagerEnvironment=</varname> setting in
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry><refentrytitle>systemd-user.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para>
|
||
|
||
<para>Some of the variables understood by <command>systemd</command>:</para>
|
||
|
||
<variablelist class='environment-variables'>
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_LEVEL</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-level-body" />
|
||
|
||
<para>This can be overridden with <option>--log-level=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_COLOR</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-color-body" />
|
||
|
||
<para>This can be overridden with <option>--log-color=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_TIME</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-time-body" />
|
||
|
||
<para>This can be overridden with <option>--log-time=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_LOCATION</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-location-body" />
|
||
|
||
<para>This can be overridden with <option>--log-location=</option>.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_TID</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-tid-body" /></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>$SYSTEMD_LOG_TARGET</varname></term>
|
||
<listitem><xi:include href="common-variables.xml" xpointer="log-target-body" />
|
||
|
||
<para>This can be overridden with <option>--log-target=</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>$SYSTEMD_UNIT_PATH</varname></term>
|
||
<term><varname>$SYSTEMD_GENERATOR_PATH</varname></term>
|
||
<term><varname>$SYSTEMD_ENVIRONMENT_GENERATOR_PATH</varname></term>
|
||
|
||
<listitem><para>Controls where systemd looks for unit files and
|
||
generators.</para>
|
||
<para>These variables may contain a list of paths, separated by colons
|
||
(<literal>:</literal>). When set, if the list ends with an empty
|
||
component (<literal>...:</literal>), this list is prepended to the
|
||
usual set of paths. Otherwise, the specified list replaces the usual
|
||
set of paths.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<xi:include href="common-variables.xml" xpointer="pager"/>
|
||
<xi:include href="common-variables.xml" xpointer="less"/>
|
||
<xi:include href="common-variables.xml" xpointer="lesscharset"/>
|
||
<xi:include href="common-variables.xml" xpointer="lesssecure"/>
|
||
<xi:include href="common-variables.xml" xpointer="colors"/>
|
||
<xi:include href="common-variables.xml" xpointer="urlify"/>
|
||
|
||
<varlistentry>
|
||
<term><varname>$LISTEN_PID</varname></term>
|
||
<term><varname>$LISTEN_FDS</varname></term>
|
||
<term><varname>$LISTEN_FDNAMES</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>
|
||
|
||
<para>For further environment variables understood by systemd and its various components, see <ulink
|
||
url="https://systemd.io/ENVIRONMENT">Known Environment Variables</ulink>.</para>
|
||
</refsect1>
|
||
|
||
<refsect1>
|
||
<title>Kernel Command Line</title>
|
||
|
||
<para>When run as the system instance systemd parses a number of options listed below. They can be
|
||
specified as 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>, or through the
|
||
<literal>SystemdOptions</literal> EFI variable (on EFI systems). The kernel command line has higher
|
||
priority. Following variables are understood:</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 or enables the option if specified
|
||
without an argument. If enabled, the systemd manager (PID 1) dumps core when
|
||
it crashes. Otherwise, no core dump is created. Defaults to enabled.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.crash_chvt</varname></term>
|
||
|
||
<listitem><para>Takes a positive integer, or a boolean argument. Can be also specified without an
|
||
argument, with the same effect as a positive boolean. If a positive integer (in the range 1–63) is
|
||
specified, the system manager (PID 1) will activate the specified virtual terminal when it crashes.
|
||
Defaults to disabled, meaning that no such switch is attempted. If set to enabled, the virtual
|
||
terminal the kernel messages are written to is used instead.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.crash_shell</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or enables the option if specified
|
||
without an argument. If enabled, the system manager (PID 1) spawns a shell
|
||
when it crashes, after a 10s delay. Otherwise, no shell is spawned. Defaults
|
||
to disabled, for security reasons, as the shell is not protected by password
|
||
authentication.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.crash_reboot</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or enables the option if specified
|
||
without an argument. If enabled, the system manager (PID 1) will reboot the
|
||
machine automatically when it crashes, after a 10s delay. Otherwise, the
|
||
system will hang indefinitely. Defaults to disabled, in order to avoid a
|
||
reboot loop. If combined with <varname>systemd.crash_shell</varname>, the
|
||
system is rebooted after the shell exits.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.confirm_spawn</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or a path to the virtual console
|
||
where the confirmation messages should be emitted. Can be also specified
|
||
without an argument, with the same effect as a positive boolean. If enabled,
|
||
the system manager (PID 1) asks for confirmation when spawning processes
|
||
using <option>/dev/console</option>. If a path or a console name (such as
|
||
<literal>ttyS0</literal>) is provided, the virtual console pointed to by this
|
||
path or described by the give name will be used instead. Defaults to disabled.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.service_watchdogs=</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument. If disabled, all service runtime
|
||
watchdogs (<option>WatchdogSec=</option>) and emergency actions (e.g.
|
||
<option>OnFailure=</option> or <option>StartLimitAction=</option>) are
|
||
ignored by the system manager (PID 1); see
|
||
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
Defaults to enabled, i.e. watchdogs and failure actions are processed
|
||
normally. The hardware watchdog is not affected by this
|
||
option.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.show_status</varname></term>
|
||
|
||
<listitem><para>Takes a boolean argument or the constants <constant>error</constant> and
|
||
<constant>auto</constant>. Can be also specified without an argument, with the same effect as a
|
||
positive boolean. If enabled, the systemd manager (PID 1) shows terse service status updates on the
|
||
console during bootup. With <constant>error</constant>, only messages about failures are shown, but
|
||
boot is otherwise quiet. <constant>auto</constant> behaves like <option>false</option> until there is
|
||
a significant delay in boot. Defaults to enabled, unless <option>quiet</option> is passed as kernel
|
||
command line option, in which case it defaults to <constant>error</constant>. If specified overrides
|
||
the system manager configuration file option <option>ShowStatus=</option>, see
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.status_unit_format=</varname></term>
|
||
|
||
<listitem><para>Takes <option>name</option>, <option>description</option> or
|
||
<option>combined</option> as the value. If <option>name</option>, the system manager will use unit
|
||
names in status messages. If <option>combined</option>, the system manager will use unit names and
|
||
description in status messages. When specified, overrides the system manager configuration file
|
||
option <option>StatusUnitFormat=</option>, see
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.log_color</varname></term>
|
||
<term><varname>systemd.log_level=</varname></term>
|
||
<term><varname>systemd.log_location</varname></term>
|
||
<term><varname>systemd.log_target=</varname></term>
|
||
<term><varname>systemd.log_time</varname></term>
|
||
<term><varname>systemd.log_tid</varname></term>
|
||
|
||
<listitem><para>Controls log output, with the same effect as the
|
||
<varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>,
|
||
<varname>$SYSTEMD_LOG_LOCATION</varname>, <varname>$SYSTEMD_LOG_TARGET</varname>,
|
||
<varname>$SYSTEMD_LOG_TIME</varname>, and <varname>$SYSTEMD_LOG_TID</varname> environment variables
|
||
described above. <varname>systemd.log_color</varname>, <varname>systemd.log_location</varname>,
|
||
<varname>systemd.log_time</varname>, and <varname>systemd.log_tid=</varname> can be specified without
|
||
an argument, with the same effect as a positive boolean.</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 and sockets. 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>kmsg</option>,
|
||
<option>kmsg+console</option>. If the argument is omitted
|
||
<varname>systemd.default-standard-output=</varname> defaults to <option>journal</option> and
|
||
<varname>systemd.default-standard-error=</varname> to <option>inherit</option>.</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>systemd.machine_id=</varname></term>
|
||
|
||
<listitem><para>Takes a 32 character hex value to be
|
||
used for setting the machine-id. Intended mostly for
|
||
network booting where the same machine-id is desired
|
||
for every boot.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.unified_cgroup_hierarchy</varname></term>
|
||
|
||
<listitem><para>When specified without an argument or with a true argument,
|
||
enables the usage of
|
||
<ulink url="https://www.kernel.org/doc/html/latest/admin-guide/cgroup-v2.html">unified cgroup hierarchy</ulink>
|
||
(a.k.a. cgroups-v2). When specified with a false argument, fall back to
|
||
hybrid or full legacy cgroup hierarchy.</para>
|
||
|
||
<para>If this option is not specified, the default behaviour is determined
|
||
during compilation (the <option>-Ddefault-hierarchy=</option> meson
|
||
option). If the kernel does not support unified cgroup hierarchy, the legacy
|
||
hierarchy will be used even if this option is specified.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
|
||
|
||
<listitem><para>Takes effect if the full unified cgroup hierarchy is not used
|
||
(see previous option). When specified without an argument or with a true
|
||
argument, disables the use of "hybrid" cgroup hierarchy (i.e. a cgroups-v2
|
||
tree used for systemd, and
|
||
<ulink url="https://www.kernel.org/doc/Documentation/cgroup-v1/">legacy
|
||
cgroup hierarchy</ulink>, a.k.a. cgroups-v1, for other controllers), and
|
||
forces a full "legacy" mode. When specified with a false argument, enables
|
||
the use of "hybrid" hierarchy.</para>
|
||
|
||
<para>If this option is not specified, the default behaviour is determined
|
||
during compilation (the <option>-Ddefault-hierarchy=</option> meson
|
||
option). If the kernel does not support unified cgroup hierarchy, the legacy
|
||
hierarchy will be used even if this option is specified.</para>
|
||
</listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>quiet</varname></term>
|
||
|
||
<listitem><para>Turn off status output at boot, much like
|
||
<varname>systemd.show_status=no</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>rd.emergency</varname></term>
|
||
<term><varname>-b</varname></term>
|
||
|
||
<listitem><para>Boot into emergency mode. This is equivalent
|
||
to <varname>systemd.unit=emergency.target</varname> or
|
||
<varname>rd.systemd.unit=emergency.target</varname>, respectively, and
|
||
provided for compatibility reasons and to be easier to type.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><varname>rescue</varname></term>
|
||
<term><varname>rd.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> or
|
||
<varname>rd.systemd.unit=rescue.target</varname>, respectively, 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 project='man-pages'><refentrytitle>locale.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
and
|
||
<citerefentry project='man-pages'><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>Options</title>
|
||
|
||
<para><command>systemd</command> is only very rarely invoked directly, since it is started early and is
|
||
already running by the time users may interact with it. Normally, tools like
|
||
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> are used to
|
||
give commands to the manager. Since <command>systemd</command> is usually not invoked directly, the
|
||
options listed below are mostly useful for debugging and special purposes.</para>
|
||
|
||
<refsect2>
|
||
<title>Introspection and debugging options</title>
|
||
|
||
<para>Those options are used for testing and introspection, and <command>systemd</command> may
|
||
be invoked with them at any time:</para>
|
||
|
||
<variablelist>
|
||
<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>--dump-bus-properties</option></term>
|
||
|
||
<listitem><para>Dump exposed bus properties. This outputs a terse but complete list of properties
|
||
exposed on D-Bus.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--test</option></term>
|
||
|
||
<listitem><para>Determine the initial start-up transaction (i.e. the list of jobs enqueued at
|
||
start-up), dump it and exit — without actually executing any of the determined jobs. This option is
|
||
useful for debugging only. Note that during regular service manager start-up additional units not
|
||
shown by this operation may be started, because hardware, socket, bus or other kinds of activation
|
||
might add additional jobs as the transaction is executed. Use <option>--system</option> to request
|
||
the initial transaction of the system service manager (this is also the implied default), combine
|
||
with <option>--user</option> to request the initial transaction of the per-user service manager
|
||
instead.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--system</option></term>
|
||
<term><option>--user</option></term>
|
||
|
||
<listitem><para>When used in conjunction with <option>--test</option>, selects whether to calculate
|
||
the initial transaction for the system instance or for a per-user instance. These options have no
|
||
effect when invoked without <option>--test</option>, as during regular
|
||
(i.e. non-<option>--test</option>) invocations the service manager will automatically detect
|
||
whether it shall operate in system or per-user mode, by checking whether the PID it is run as is 1
|
||
or not. Note that it is not supported booting and maintaining a system with the service manager
|
||
running in <option>--system</option> mode but with a PID other than 1.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<xi:include href="standard-options.xml" xpointer="help" />
|
||
<xi:include href="standard-options.xml" xpointer="version" />
|
||
</variablelist>
|
||
</refsect2>
|
||
|
||
<refsect2>
|
||
<title>Options that duplicate kernel command line settings</title>
|
||
|
||
<para>Those options correspond directly to options listed above in "Kernel Command Line". Both forms
|
||
may be used equivalently for the system manager, but it is recommended to use the forms listed above in
|
||
this context, because they are properly namespaced. When an option is specified both on the kernel
|
||
command line and as a normal command line argument, the latter has higher precedence.</para>
|
||
|
||
<para>When <command>systemd</command> is used as a user manager, the kernel command line is ignored and
|
||
only the options described below are understood. Nevertheless, <command>systemd</command> is usually
|
||
started in this mode through the
|
||
<citerefentry><refentrytitle>user@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
||
service, which is shared between all users. It may be more convenient to use configuration files to
|
||
modify settings (see
|
||
<citerefentry><refentrytitle>systemd-user.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
|
||
or environment variables. See the "Environment" section above for a discussion of how the environment
|
||
block is set.</para>
|
||
|
||
<variablelist>
|
||
<varlistentry>
|
||
<term><option>--unit=</option></term>
|
||
|
||
<listitem><para>Set default unit to activate on startup. If not specified, defaults to
|
||
<filename>default.target</filename>. See <varname>systemd.unit=</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--dump-core</option></term>
|
||
|
||
<listitem><para>Enable core dumping on crash. This switch has no effect when running as user
|
||
instance. Same as <varname>systemd.dump_core=</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--crash-vt=</option><replaceable>VT</replaceable></term>
|
||
|
||
<listitem><para>Switch to a specific virtual console (VT) on crash. This switch has no effect when
|
||
running as user instance. Same as <varname>systemd.crash_chvt=</varname> above (but not the
|
||
different spelling!).</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--crash-shell</option></term>
|
||
|
||
<listitem><para>Run a shell on crash. This switch has no effect when running as user instance. See
|
||
<varname>systemd.crash_shell=</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--crash-reboot</option></term>
|
||
|
||
<listitem><para>Automatically reboot the system on crash. This switch has no effect when running as
|
||
user instance. See <varname>systemd.crash_reboot</varname> above.</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. See <varname>systemd.confirm_spawn</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--show-status</option></term>
|
||
|
||
<listitem><para>Show terse unit status information on the console during boot-up and shutdown. See
|
||
<varname>systemd.show_status</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--log-color</option></term>
|
||
|
||
<listitem><para>Highlight important log messages. See <varname>systemd.log_color</varname> above.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--log-level=</option></term>
|
||
|
||
<listitem><para>Set log level. See <varname>systemd.log_level</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--log-location</option></term>
|
||
|
||
<listitem><para>Include code location in log messages. See <varname>systemd.log_location</varname>
|
||
above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--log-target=</option></term>
|
||
|
||
<listitem><para>Set log target. See <varname>systemd.log_target</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--log-time=</option></term>
|
||
|
||
<listitem><para>Prefix console messages with timestamp. See <varname>systemd.log_time</varname> above.
|
||
</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--machine-id=</option></term>
|
||
|
||
<listitem><para>Override the machine-id set on the hard drive. See
|
||
<varname>systemd.machine_id=</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
|
||
<varlistentry>
|
||
<term><option>--service-watchdogs</option></term>
|
||
|
||
<listitem><para>Globally enable/disable all service watchdog timeouts and emergency actions. See
|
||
<varname>systemd.service_watchdogs</varname> above.</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. See <varname>systemd.default_standard_output=</varname> and
|
||
<varname>systemd.default_standard_error=</varname> above.</para></listitem>
|
||
</varlistentry>
|
||
</variablelist>
|
||
</refsect2>
|
||
</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/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="https://www.freedesktop.org/wiki/Software/systemd/">systemd Homepage</ulink>,
|
||
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry project='man-pages'><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>org.freedesktop.systemd1</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
||
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</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>
|