systemd/man/systemctl.xml
2013-07-26 20:01:33 -04:00

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<?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">
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<refentry id="systemctl">
<refentryinfo>
<title>systemctl</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>systemctl</refentrytitle>
<manvolnum>1</manvolnum>
</refmeta>
<refnamediv>
<refname>systemctl</refname>
<refpurpose>Control the systemd system and service manager</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>systemctl</command>
<arg choice="opt" rep="repeat">OPTIONS</arg>
<arg choice="plain">COMMAND</arg>
<arg choice="opt" rep="repeat">NAME</arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><command>systemctl</command> may be used to
introspect and control the state of the
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
system and service manager.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>The following options are understood:</para>
<variablelist>
<varlistentry>
<term><option>-h</option></term>
<term><option>--help</option></term>
<listitem><para>Prints a short help
text and exits.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--version</option></term>
<listitem>
<para>Prints a short version string and exits.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</option></term>
<term><option>--type=</option></term>
<listitem>
<para>The argument should be a comma-separated list of unit
types such as <option>service</option> and
<option>socket</option>.
</para>
<para>If one of the arguments is a unit type, when listing
units, limit display to certain unit types. Otherwise, units
of all types will be shown.</para>
<para>As a special case, if one of the arguments is
<option>help</option>, a list of allowed values will be
printed and the program will exit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--state=</option></term>
<listitem>
<para>The argument should be a comma-separated list of unit LOAD
or SUB or ACTIVE states. When listing units, show only those
with specified LOAD or SUB or ACTIVE state.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-p</option></term>
<term><option>--property=</option></term>
<listitem>
<para>When showing unit/job/manager properties with the
<command>show</command> command, limit display to certain
properties as specified as argument. If not specified, all
set properties are shown. The argument should be a
comma-separated list of property names, such as
<literal>MainPID</literal>. If specified more than once, all
properties with the specified names are shown.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-a</option></term>
<term><option>--all</option></term>
<listitem>
<para>When listing units, show all loaded units, regardless
of their state, including inactive units. When showing
unit/job/manager properties, show all properties regardless
whether they are set or not.</para>
<para>To list all units installed on the system, use the
<command>list-unit-files</command> command instead.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--reverse</option></term>
<listitem>
<para>Show reverse dependencies between units with
<command>list-dependencies</command>, i.e. units with
dependencies of type <varname>Wants=</varname> or
<varname>Requires=</varname> on the given unit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--after</option></term>
<term><option>--before</option></term>
<listitem>
<para>Show which units are started after or before
with <command>list-dependencies</command>, respectively.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-l</option></term>
<term><option>--full</option></term>
<listitem>
<para>Do not ellipsize unit names, cgroup members, and
truncate unit descriptions in the output of
<command>list-units</command> and
<command>list-jobs</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--fail</option></term>
<listitem>
<para>If the requested operation conflicts with a pending
unfinished job, fail the command. If this is not specified,
the requested operation will replace the pending job, if
necessary. Do not confuse with
<option>--failed</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--show-types</option></term>
<listitem>
<para>When showing sockets, show the type of the socket.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--irreversible</option></term>
<listitem>
<para>Mark this transaction's jobs as irreversible. This prevents
future conflicting transactions from replacing these jobs.
The jobs can still be cancelled using the <command>cancel</command>
command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--ignore-dependencies</option></term>
<listitem>
<para>When enqueuing a new job, ignore all its dependencies
and execute it immediately. If passed, no required units of
the unit passed will be pulled in, and no ordering
dependencies will be honored. This is mostly a debugging and
rescue tool for the administrator and should not be used by
applications.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-i</option></term>
<term><option>--ignore-inhibitors</option></term>
<listitem>
<para>When system shutdown or a sleep state is requested,
ignore inhibitor locks. Applications can establish inhibitor
locks to avoid that certain important operations (such as CD
burning or suchlike) are interrupted by system shutdown or a
sleep state. Any user may take these locks and privileged
users may override these locks. If any locks are taken,
shutdown and sleep state requests will normally fail
(regardless if privileged or not) and a list of active locks
is printed. However, if <option>--ignore-inhibitors</option>
is specified, the locks are ignored and not printed, and the
operation attempted anyway, possibly requiring additional
privileges.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-q</option></term>
<term><option>--quiet</option></term>
<listitem>
<para>Suppress output to standard output in
<command>snapshot</command>,
<command>is-active</command>,
<command>is-failed</command>,
<command>enable</command> and
<command>disable</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-block</option></term>
<listitem>
<para>Do not synchronously wait for the requested operation
to finish. If this is not specified, the job will be
verified, enqueued and <command>systemctl</command> will
wait until it is completed. By passing this argument, it is
only verified and enqueued.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-legend</option></term>
<listitem>
<para>Do not print a legend, i.e. the column headers and
the footer with hints.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-pager</option></term>
<listitem>
<para>Do not pipe output into a pager.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--system</option></term>
<listitem>
<para>Talk to the systemd system manager. (Default)</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--user</option></term>
<listitem>
<para>Talk to the systemd manager of the calling
user.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-wall</option></term>
<listitem>
<para>Do not send wall message before halt, power-off,
reboot.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--global</option></term>
<listitem>
<para>When used with <command>enable</command> and
<command>disable</command>, operate on the global user
configuration directory, thus enabling or disabling a unit
file globally for all future logins of all users.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-reload</option></term>
<listitem>
<para>When used with <command>enable</command> and
<command>disable</command>, do not implicitly reload daemon
configuration after executing the changes.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--no-ask-password</option></term>
<listitem>
<para>When used with <command>start</command> and related
commands, disables asking for passwords. Background services
may require input of a password or passphrase string, for
example to unlock system hard disks or cryptographic
certificates. Unless this option is specified and the
command is invoked from a terminal,
<command>systemctl</command> will query the user on the
terminal for the necessary secrets. Use this option to
switch this behavior off. In this case, the password must be
supplied by some other means (for example graphical password
agents) or the service might fail. This also disables
querying the user for authentication for privileged
operations.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--kill-who=</option></term>
<listitem>
<para>When used with <command>kill</command>, choose which
processes to kill. Must be one of <option>main</option>,
<option>control</option> or <option>all</option> to select
whether to kill only the main process of the unit, the
control process or all processes of the unit. If omitted,
defaults to <option>all</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s</option></term>
<term><option>--signal=</option></term>
<listitem>
<para>When used with <command>kill</command>, choose which
signal to send to selected processes. Must be one of the
well known signal specifiers such as <constant>SIGTERM</constant>, <constant>SIGINT</constant> or
<constant>SIGSTOP</constant>. If omitted, defaults to
<option>SIGTERM</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-f</option></term>
<term><option>--force</option></term>
<listitem>
<para>When used with <command>enable</command>, overwrite
any existing conflicting symlinks.</para>
<para>When used with <command>halt</command>,
<command>poweroff</command>, <command>reboot</command> or
<command>kexec</command>, execute the selected operation
without shutting down all units. However, all processes will
be killed forcibly and all file systems are unmounted or
remounted read-only. This is hence a drastic but relatively
safe option to request an immediate reboot. If
<option>--force</option> is specified twice for these
operations, they will be executed immediately without
terminating any processes or umounting any file
systems. Warning: specifying <option>--force</option> twice
with any of these operations might result in data
loss.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--root=</option></term>
<listitem>
<para>When used with
<command>enable</command>/<command>disable</command>/<command>is-enabled</command>
(and related commands), use alternative root path when
looking for unit files.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--runtime</option></term>
<listitem>
<para>When used with <command>enable</command>,
<command>disable</command>, <command>is-enabled</command>
(and related commands), make changes only temporarily, so
that they are lost on the next reboot. This will have the
effect that changes are not made in subdirectories of
<filename>/etc</filename> but in <filename>/run</filename>,
with identical immediate effects, however, since the latter
is lost on reboot, the changes are lost too.</para>
<para>Similar, when used with
<command>set-property</command>, make changes only
temporarily, so that they are lost on the next
reboot.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-H</option></term>
<term><option>--host</option></term>
<listitem>
<para>Execute operation remotely. Specify a hostname, or
username and hostname separated by <literal>@</literal>, to connect to. This
will use SSH to talk to the remote systemd
instance.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-P</option></term>
<term><option>--privileged</option></term>
<listitem>
<para>Acquire privileges via PolicyKit before executing the
operation.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-n</option></term>
<term><option>--lines=</option></term>
<listitem>
<para>When used with <command>status</command>, controls the
number of journal lines to show, counting from the most
recent ones. Takes a positive integer argument. Defaults to
10.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-o</option></term>
<term><option>--output=</option></term>
<listitem>
<para>When used with <command>status</command>, controls the
formatting of the journal entries that are shown. For the
available choices, see
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
Defaults to <literal>short</literal>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>--plain</option></term>
<listitem>
<para>When used with <command>list-dependencies</command>,
the output is printed as a list instead of a tree.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Commands</title>
<para>The following commands are understood:</para>
<variablelist>
<varlistentry>
<term><command>list-units</command></term>
<listitem>
<para>List known units (subject to limitations specified
with <option>-t</option>).</para>
<para>This is the default command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>list-sockets</command></term>
<listitem>
<para>List socket units ordered by the listening address. Produces output
similar to
<programlisting>
LISTEN UNIT ACTIVATES
/dev/initctl systemd-initctl.socket systemd-initctl.service
...
[::]:22 sshd.socket sshd.service
kobject-uevent 1 systemd-udevd-kernel.socket systemd-udevd.service
5 sockets listed.
</programlisting>
Note: because the addresses might contains spaces, this output
is not suitable for programmatic consumption.
</para>
<para>See also the options <option>--show-types</option>,
<option>--all</option>, and <option>--failed</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>start <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Start (activate) one or more units specified on the
command line.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>stop <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Stop (deactivate) one or more units specified on the
command line.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reload <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Asks all units listed on the command line to reload
their configuration. Note that this will reload the
service-specific configuration, not the unit configuration
file of systemd. If you want systemd to reload the
configuration file of a unit use the
<command>daemon-reload</command> command. In other words:
for the example case of Apache, this will reload Apache's
<filename>httpd.conf</filename> in the web server, not the
<filename>apache.service</filename> systemd unit
file.</para>
<para>This command should not be confused with the
<command>daemon-reload</command> or <command>load</command>
commands.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>restart <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Restart one or more units specified on the command
line. If the units are not running yet, they will be
started.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>try-restart <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Restart one or more units specified on the command
line if the units are running. This does nothing if units are not
running. Note that, for compatibility with Red Hat init
scripts, <command>condrestart</command> is equivalent to this
command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reload-or-restart <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Reload one or more units if they support it. If not,
restart them instead. If the units are not running yet, they
will be started.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reload-or-try-restart <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Reload one or more units if they support it. If not,
restart them instead. This does nothing if the units are not
running. Note that, for compatibility with SysV init scripts,
<command>force-reload</command> is equivalent to this
command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>isolate <replaceable>NAME</replaceable></command></term>
<listitem>
<para>Start the unit specified on the command line and its
dependencies and stop all others.</para>
<para>This is similar to changing the runlevel in a
traditional init system. The <command>isolate</command>
command will immediately stop processes that are not enabled
in the new unit, possibly including the graphical
environment or terminal you are currently using.</para>
<para>Note that this is allowed only on units where
<option>AllowIsolate=</option> is enabled. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>kill <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Send a signal to one or more processes of the
unit. Use <option>--kill-who=</option> to select which
process to kill. Use <option>--kill-mode=</option> to select
the kill mode and <option>--signal=</option> to select the
signal to send.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>is-active <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Check whether any of the specified units are active
(i.e. running). Returns an exit code 0 if at least one is
active, non-zero otherwise. Unless <option>--quiet</option>
is specified, this will also print the current unit state to
STDOUT.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>is-failed <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Check whether any of the specified units are in a "failed" state.
Returns an exit code 0 if at least one has failed, non-zero
otherwise. Unless <option>--quiet</option> is specified, this
will also print the current unit state to
STDOUT.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>status [<replaceable>NAME</replaceable>...|<replaceable>PID</replaceable>...]</command></term>
<listitem>
<para>Show terse runtime status information about one or
more units, followed by most recent log data from the
journal. If no units are specified, show all units (subject
to limitations specified with <option>-t</option>). If a PID
is passed, show information about the unit the process
belongs to.</para>
<para>This function is intended to generate human-readable
output. If you are looking for computer-parsable output, use
<command>show</command> instead.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>show [<replaceable>NAME</replaceable>...|<replaceable>JOB</replaceable>...]</command></term>
<listitem>
<para>Show properties of one or more units, jobs, or the
manager itself. If no argument is specified properties of
the manager will be shown. If a unit name is specified
properties of the unit is shown, and if a job id is
specified properties of the job is shown. By default, empty
properties are suppressed. Use <option>--all</option> to
show those too. To select specific properties to show use
<option>--property=</option>. This command is intended to be
used whenever computer-parsable output is required. Use
<command>status</command> if you are looking for formatted
human-readable output.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>set-property <replaceable>NAME</replaceable> <replaceable>ASSIGNMENT</replaceable>...</command></term>
<listitem>
<para>Set the specified unit properties at runtime where
this is supported. This allows changing configuration
parameter properties such as resource management controls at
runtime. Not all properties may be changed at runtime, but
many resource management settings (primarily those in
<citerefentry><refentrytitle>systemd.cgroup</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
may. The changes are applied instantly, and stored on disk
for future boots, unless <option>--runtime</option> is
passed, in which case the settings only apply until the next
reboot. The syntax of the property assignment follows
closely the syntax of assignments in unit files.</para>
<para>Example: <command>systemctl set-property foobar.service CPUShares=777</command></para>
<para>Note that this command allows changing multiple
properties at the same time, which is preferable over
setting them individually. Like unit file configuration
settings, assigning the empty list to list parameters will
reset the list.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>help <replaceable>NAME</replaceable>...|<replaceable>PID</replaceable>...</command></term>
<listitem>
<para>Show manual pages for one or more units, if
available. If a PID is given, the manual pages for the unit
the process belongs to are shown.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reset-failed [<replaceable>NAME</replaceable>...]</command></term>
<listitem>
<para>Reset the <literal>failed</literal> state of the
specified units, or if no unit name is passed, reset the state of all
units. When a unit fails in some way (i.e. process exiting
with non-zero error code, terminating abnormally or timing
out), it will automatically enter the
<literal>failed</literal> state and its exit code and status
is recorded for introspection by the administrator until the
service is restarted or reset with this command.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>list-unit-files</command></term>
<listitem>
<para>List installed unit files.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>enable <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Enable one or more unit files or unit file instances,
as specified on the command line. This will create a number
of symlinks as encoded in the <literal>[Install]</literal>
sections of the unit files. After the symlinks have been
created, the systemd configuration is reloaded (in a way that
is equivalent to <command>daemon-reload</command>) to ensure
the changes are taken into account immediately. Note that
this does <emphasis>not</emphasis> have the effect of also
starting any of the units being enabled. If this
is desired, a separate <command>start</command> command must
be invoked for the unit. Also note that in case of instance
enablement, symlinks named the same as instances are created in
the install location, however they all point to the same
template unit file.</para>
<para>This command will print the actions executed. This
output may be suppressed by passing <option>--quiet</option>.
</para>
<para>Note that this operation creates only the suggested
symlinks for the units. While this command is the
recommended way to manipulate the unit configuration
directory, the administrator is free to make additional
changes manually by placing or removing symlinks in the
directory. This is particularly useful to create
configurations that deviate from the suggested default
installation. In this case, the administrator must make sure
to invoke <command>daemon-reload</command> manually as
necessary to ensure the changes are taken into account.
</para>
<para>Enabling units should not be confused with starting
(activating) units, as done by the <command>start</command>
command. Enabling and starting units is orthogonal: units
may be enabled without being started and started without
being enabled. Enabling simply hooks the unit into various
suggested places (for example, so that the unit is
automatically started on boot or when a particular kind of
hardware is plugged in). Starting actually spawns the daemon
process (in case of service units), or binds the socket (in
case of socket units), and so on.</para>
<para>Depending on whether <option>--system</option>,
<option>--user</option> or <option>--global</option> is
specified, this enables the unit for the system, for the
calling user only or for all future logins of all
users. Note that in the last case, no systemd daemon
configuration is reloaded.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>disable <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Disables one or more units. This removes all symlinks
to the specified unit files from the unit configuration
directory, and hence undoes the changes made by
<command>enable</command>. Note however that this removes
all symlinks to the unit files (i.e. including manual
additions), not just those actually created by
<command>enable</command>. This call implicitly reloads the
systemd daemon configuration after completing the disabling
of the units. Note that this command does not implicitly
stop the units that are being disabled. If this is desired,
an additional <command>stop</command> command should be
executed afterwards.</para>
<para>This command will print the actions executed. This
output may be suppressed by passing <option>--quiet</option>.
</para>
<para>This command honors <option>--system</option>,
<option>--user</option>, <option>--global</option> in a
similar way as <command>enable</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>is-enabled <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Checks whether any of the specified unit files are
enabled (as with <command>enable</command>). Returns an exit
code of 0 if at least one is enabled, non-zero
otherwise. Prints the current enable status. To suppress
this output, use <option>--quiet</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reenable <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Reenable one or more unit files, as specified on the
command line. This is a combination of
<command>disable</command> and <command>enable</command> and
is useful to reset the symlinks a unit is enabled with to
the defaults configured in the <literal>[Install]</literal>
section of the unit file.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>preset <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Reset one or more unit files, as specified on the
command line, to the defaults configured in the preset
policy files. This has the same effect as
<command>disable</command> or <command>enable</command>,
depending how the unit is listed in the preset files. For
more information on the preset policy format, see
<citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
For more information on the concept of presets, please
consult the
<ulink url="http://freedesktop.org/wiki/Software/systemd/Preset">Preset</ulink>
document.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>mask <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Mask one or more unit files, as specified on the
command line. This will link these units to
<filename>/dev/null</filename>, making it impossible to
start them. This is a stronger version of
<command>disable</command>, since it prohibits all kinds of
activation of the unit, including manual activation. Use
this option with care.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>unmask <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Unmask one or more unit files, as specified on the
command line. This will undo the effect of
<command>mask</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>link <replaceable>FILENAME</replaceable>...</command></term>
<listitem>
<para>Link a unit file that is not in the unit file search
paths into the unit file search path. This requires an
absolute path to a unit file. The effect of this can be
undone with <command>disable</command>. The effect of this
command is that a unit file is available for
<command>start</command> and other commands although it
is not installed directly in the unit search path.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>get-default</command></term>
<listitem>
<para>Get the default target specified
via <filename>default.target</filename> link.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>set-default <replaceable>NAME</replaceable></command></term>
<listitem>
<para>Set the default target to boot into. Command links
<filename>default.target</filename> to the given unit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>list-jobs</command></term>
<listitem>
<para>List jobs that are in progress.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>cancel <replaceable>JOB</replaceable>...</command></term>
<listitem>
<para>Cancel one or more jobs specified on the command line
by their numeric job IDs. If no job ID is specified, cancel
all pending jobs.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>list-dependencies <replaceable>NAME</replaceable></command></term>
<listitem>
<para>Shows required and wanted units of the specified
unit. If no unit is specified,
<filename>default.target</filename> is implied. Target units
are recursively expanded. When <option>--all</option> is
passed, all other units are recursively expanded as
well.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>snapshot [<replaceable>NAME</replaceable>]</command></term>
<listitem>
<para>Create a snapshot. If a snapshot name is specified,
the new snapshot will be named after it. If none is
specified, an automatic snapshot name is generated. In either
case, the snapshot name used is printed to STDOUT, unless
<option>--quiet</option> is specified.</para>
<para>A snapshot refers to a saved state of the systemd
manager. It is implemented itself as a unit that is
generated dynamically with this command and has dependencies
on all units active at the time. At a later time, the user
may return to this state by using the
<command>isolate</command> command on the snapshot unit.
</para>
<para>Snapshots are only useful for saving and restoring
which units are running or are stopped, they do not
save/restore any other state. Snapshots are dynamic and lost
on reboot.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>delete <replaceable>NAME</replaceable>...</command></term>
<listitem>
<para>Remove a snapshot previously created with
<command>snapshot</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>daemon-reload</command></term>
<listitem>
<para>Reload systemd manager configuration. This will reload
all unit files and recreate the entire dependency
tree. While the daemon is reloaded, all sockets systemd
listens on on behalf of user configuration will stay
accessible.</para> <para>This command should not be confused
with the <command>load</command> or
<command>reload</command> commands.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>daemon-reexec</command></term>
<listitem>
<para>Reexecute the systemd manager. This will serialize the
manager state, reexecute the process and deserialize the
state again. This command is of little use except for
debugging and package upgrades. Sometimes it might be
helpful as a heavy-weight <command>daemon-reload</command>.
While the daemon is reexecuted, all sockets systemd listening
on behalf of user configuration will stay accessible.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>show-environment</command></term>
<listitem>
<para>Dump the systemd manager environment block. The
environment block will be dumped in straight-forward form
suitable for sourcing into a shell script. This environment
block will be passed to all processes the manager
spawns.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>set-environment <replaceable>VARIABLE=VALUE</replaceable>...</command></term>
<listitem>
<para>Set one or more systemd manager environment variables,
as specified on the command line.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>unset-environment <replaceable>VARIABLE</replaceable>...</command></term>
<listitem>
<para>Unset one or more systemd manager environment
variables. If only a variable name is specified, it will be
removed regardless of its value. If a variable and a value
are specified, the variable is only removed if it has the
specified value.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>default</command></term>
<listitem>
<para>Enter default mode. This is mostly equivalent to
<command>isolate default.target</command>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>rescue</command></term>
<listitem>
<para>Enter rescue mode. This is mostly equivalent to
<command>isolate rescue.target</command>, but also prints a
wall message to all users.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>emergency</command></term>
<listitem>
<para>Enter emergency mode. This is mostly equivalent to
<command>isolate emergency.target</command>, but also prints
a wall message to all users.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>halt</command></term>
<listitem>
<para>Shut down and halt the system. This is mostly equivalent to
<command>start halt.target --irreversible</command>, but also
prints a wall message to all users. If combined with
<option>--force</option>, shutdown of all running services is
skipped, however all processes are killed and all file
systems are unmounted or mounted read-only, immediately
followed by the system halt. If <option>--force</option> is
specified twice, the operation is immediately executed
without terminating any processes or unmounting any file
systems. This may result in data loss.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>poweroff</command></term>
<listitem>
<para>Shut down and power-off the system. This is mostly
equivalent to <command>start poweroff.target --irreversible</command>,
but also prints a wall message to all users. If combined with
<option>--force</option>, shutdown of all running services is
skipped, however all processes are killed and all file
systems are unmounted or mounted read-only, immediately
followed by the powering off. If <option>--force</option> is
specified twice, the operation is immediately executed
without terminating any processes or unmounting any file
systems. This may result in data loss.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>reboot</command></term>
<listitem>
<para>Shut down and reboot the system. This is mostly
equivalent to <command>start reboot.target --irreversible</command>,
but also prints a wall message to all users. If combined with
<option>--force</option>, shutdown of all running services is
skipped, however all processes are killed and all file
systems are unmounted or mounted read-only, immediately
followed by the reboot. If <option>--force</option> is
specified twice, the operation is immediately executed
without terminating any processes or unmounting any file
systems. This may result in data loss.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>kexec</command></term>
<listitem>
<para>Shut down and reboot the system via kexec. This is
mostly equivalent to <command>start kexec.target --irreversible</command>,
but also prints a wall message to all users. If combined
with <option>--force</option>, shutdown of all running
services is skipped, however all processes are killed and
all file systems are unmounted or mounted read-only,
immediately followed by the reboot.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>exit</command></term>
<listitem>
<para>Ask the systemd manager to quit. This is only
supported for user service managers (i.e. in conjunction
with the <option>--user</option> option) and will fail
otherwise.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>suspend</command></term>
<listitem>
<para>Suspend the system. This will trigger activation of
the special <filename>suspend.target</filename> target.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>hibernate</command></term>
<listitem>
<para>Hibernate the system. This will trigger activation of
the special <filename>hibernate.target</filename> target.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>hybrid-sleep</command></term>
<listitem>
<para>Hibernate and suspend the system. This will trigger
activation of the special
<filename>hybrid-sleep.target</filename> target.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><command>switch-root <replaceable>ROOT</replaceable> [<replaceable>INIT</replaceable>]</command></term>
<listitem>
<para>Switches to a different root directory and executes a
new system manager process below it. This is intended for
usage in initial RAM disks ("initrd"), and will transition
from the initrd's system manager process (a.k.a "init"
process) to the main system manager process. This call takes two
arguments: the directory that is to become the new root directory, and
the path to the new system manager binary below it to
execute as PID 1. If the latter is omitted or the empty
string, a systemd binary will automatically be searched for
and used as init. If the system manager path is omitted or
equal to the empty string, the state of the initrd's system
manager process is passed to the main system manager, which
allows later introspection of the state of the services
involved in the initrd boot.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit status</title>
<para>On success, 0 is returned, a non-zero failure
code otherwise.</para>
</refsect1>
<refsect1>
<title>Environment</title>
<variablelist class='environment-variables'>
<varlistentry>
<term><varname>$SYSTEMD_PAGER</varname></term>
<listitem>
<para>Pager to use when <option>--no-pager</option> is not
given; overrides <varname>$PAGER</varname>. Setting this to
an empty string or the value <literal>cat</literal> is
equivalent to passing
<option>--no-pager</option>.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.cgroup</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>