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189 lines
9.9 KiB
XML
189 lines
9.9 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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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">
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<!-- SPDX-License-Identifier: LGPL-2.1+ -->
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<refentry id="systemd.kill">
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<refentryinfo>
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<title>systemd.kill</title>
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<productname>systemd</productname>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.kill</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.kill</refname>
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<refpurpose>Process killing procedure
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configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename><replaceable>service</replaceable>.service</filename>,
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<filename><replaceable>socket</replaceable>.socket</filename>,
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<filename><replaceable>mount</replaceable>.mount</filename>,
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<filename><replaceable>swap</replaceable>.swap</filename>,
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<filename><replaceable>scope</replaceable>.scope</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>Unit configuration files for services, sockets, mount
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points, swap devices and scopes share a subset of configuration
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options which define the killing procedure of processes belonging
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to the unit.</para>
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<para>This man page lists the configuration options shared by
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these five unit types. See
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for the common options shared by all unit configuration files, and
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more information on the configuration file options specific to
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each unit type.</para>
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<para>The kill procedure configuration options are configured in
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the [Service], [Socket], [Mount] or [Swap] section, depending on
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the unit type.</para>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<variablelist class='unit-directives'>
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<varlistentry>
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<term><varname>KillMode=</varname></term>
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<listitem><para>Specifies how processes of this unit shall be killed. One of
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<option>control-group</option>, <option>mixed</option>, <option>process</option>,
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<option>none</option>.</para>
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<para>If set to <option>control-group</option>, all remaining processes in the control group of this
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unit will be killed on unit stop (for services: after the stop command is executed, as configured
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with <varname>ExecStop=</varname>). If set to <option>mixed</option>, the
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<constant>SIGTERM</constant> signal (see below) is sent to the main process while the subsequent
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<constant>SIGKILL</constant> signal (see below) is sent to all remaining processes of the unit's
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control group. If set to <option>process</option>, only the main process itself is killed (not
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recommended!). If set to <option>none</option>, no process is killed (strongly recommended
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against!). In this case, only the stop command will be executed on unit stop, but no process will be
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killed otherwise. Processes remaining alive after stop are left in their control group and the
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control group continues to exist after stop unless empty.</para>
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<para>Note that it is not recommended to set <varname>KillMode=</varname> to
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<constant>process</constant> or even <constant>none</constant>, as this allows processes to escape
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the service manager's lifecycle and resource management, and to remain running even while their
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service is considered stopped and is assumed to not consume any resources.</para>
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<para>Processes will first be terminated via <constant>SIGTERM</constant> (unless the signal to send
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is changed via <varname>KillSignal=</varname> or <varname>RestartKillSignal=</varname>). Optionally,
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this is immediately followed by a <constant>SIGHUP</constant> (if enabled with
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<varname>SendSIGHUP=</varname>). If processes still remain after the main process of a unit has
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exited or the delay configured via the <varname>TimeoutStopSec=</varname> has passed, the termination
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request is repeated with the <constant>SIGKILL</constant> signal or the signal specified via
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<varname>FinalKillSignal=</varname> (unless this is disabled via the <varname>SendSIGKILL=</varname>
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option). See <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
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for more information.</para>
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<para>Defaults to <option>control-group</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>KillSignal=</varname></term>
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<listitem><para>Specifies which signal to use when stopping a service. This controls the signal that
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is sent as first step of shutting down a unit (see above), and is usually followed by
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<constant>SIGKILL</constant> (see above and below). For a list of valid signals, see
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<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
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Defaults to <constant>SIGTERM</constant>.</para>
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<para>Note that, right after sending the signal specified in this setting, systemd will always send
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<constant>SIGCONT</constant>, to ensure that even suspended tasks can be terminated cleanly.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>RestartKillSignal=</varname></term>
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<listitem><para>Specifies which signal to use when restarting a service. The same as
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<varname>KillSignal=</varname> described above, with the exception that this setting is used in a
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restart job. Not set by default, and the value of <varname>KillSignal=</varname> is used.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SendSIGHUP=</varname></term>
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<listitem><para>Specifies whether to send
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<constant>SIGHUP</constant> to remaining processes immediately
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after sending the signal configured with
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<varname>KillSignal=</varname>. This is useful to indicate to
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shells and shell-like programs that their connection has been
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severed. Takes a boolean value. Defaults to "no".
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>SendSIGKILL=</varname></term>
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<listitem><para>Specifies whether to send
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<constant>SIGKILL</constant> (or the signal specified by
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<varname>FinalKillSignal=</varname>) to remaining processes
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after a timeout, if the normal shutdown procedure left
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processes of the service around. When disabled, a
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<varname>KillMode=</varname> of <constant>control-group</constant>
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or <constant>mixed</constant> service will not restart if
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processes from prior services exist within the control group.
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Takes a boolean value. Defaults to "yes".
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>FinalKillSignal=</varname></term>
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<listitem><para>Specifies which signal to send to remaining
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processes after a timeout if <varname>SendSIGKILL=</varname>
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is enabled. The signal configured here should be one that is
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not typically caught and processed by services (<constant>SIGTERM</constant>
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is not suitable). Developers can find it useful to use this to
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generate a coredump to troubleshoot why a service did not
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terminate upon receiving the initial <constant>SIGTERM</constant>
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signal. This can be achieved by configuring <varname>LimitCORE=</varname>
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and setting <varname>FinalKillSignal=</varname> to either
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<constant>SIGQUIT</constant> or <constant>SIGABRT</constant>
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Defaults to <constant>SIGKILL</constant>.
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>WatchdogSignal=</varname></term>
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<listitem><para>Specifies which signal to use to terminate the
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service when the watchdog timeout expires (enabled through
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<varname>WatchdogSec=</varname>). Defaults to <constant>SIGABRT</constant>.
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</para></listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
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<citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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