man/systemd.kill.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="systemd.kill">
   7   <refentryinfo>
   8     <title>systemd.kill</title>
   9     <productname>systemd</productname>
  10   </refentryinfo>
  11
  12   <refmeta>
  13     <refentrytitle>systemd.kill</refentrytitle>
  14     <manvolnum>5</manvolnum>
  15   </refmeta>
  16
  17   <refnamediv>
  18     <refname>systemd.kill</refname>
  19     <refpurpose>Process killing procedure
  20     configuration</refpurpose>
  21   </refnamediv>
  22
  23   <refsynopsisdiv>
  24     <para><filename><replaceable>service</replaceable>.service</filename>,
  25     <filename><replaceable>socket</replaceable>.socket</filename>,
  26     <filename><replaceable>mount</replaceable>.mount</filename>,
  27     <filename><replaceable>swap</replaceable>.swap</filename>,
  28     <filename><replaceable>scope</replaceable>.scope</filename></para>
  29   </refsynopsisdiv>
  30
  31   <refsect1>
  32     <title>Description</title>
  33
  34     <para>Unit configuration files for services, sockets, mount
  35     points, swap devices and scopes share a subset of configuration
  36     options which define the killing procedure of processes belonging
  37     to the unit.</para>
  38
  39     <para>This man page lists the configuration options shared by
  40     these five unit types. See
  41     <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  42     for the common options shared by all unit configuration files, and
  43     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  44     <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  45     <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  46     <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  47     and
  48     <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
  49     for more information on the configuration file options specific to
  50     each unit type.</para>
  51
  52     <para>The kill procedure configuration options are configured in
  53     the [Service], [Socket], [Mount] or [Swap] section, depending on
  54     the unit type.</para>
  55   </refsect1>
  56
  57   <refsect1>
  58     <title>Options</title>
  59
  60     <variablelist class='unit-directives'>
  61
  62       <varlistentry>
  63         <term><varname>KillMode=</varname></term>
  64         <listitem><para>Specifies how processes of this unit shall be
  65         killed. One of
  66         <option>control-group</option>,
  67         <option>process</option>,
  68         <option>mixed</option>,
  69         <option>none</option>.</para>
  70
  71         <para>If set to <option>control-group</option>, all remaining
  72         processes in the control group of this unit will be killed on
  73         unit stop (for services: after the stop command is executed,
  74         as configured with <varname>ExecStop=</varname>). If set to
  75         <option>process</option>, only the main process itself is
  76         killed. If set to <option>mixed</option>, the
  77         <constant>SIGTERM</constant> signal (see below) is sent to the
  78         main process while the subsequent <constant>SIGKILL</constant>
  79         signal (see below) is sent to all remaining processes of the
  80         unit's control group. If set to <option>none</option>, no
  81         process is killed. In this case, only the stop command will be
  82         executed on unit stop, but no process be killed otherwise.
  83         Processes remaining alive after stop are left in their control
  84         group and the control group continues to exist after stop
  85         unless it is empty.</para>
  86
  87         <para>Processes will first be terminated via <constant>SIGTERM</constant> (unless the signal to send
  88         is changed via <varname>KillSignal=</varname>). Optionally, this is immediately followed by a
  89         <constant>SIGHUP</constant> (if enabled with <varname>SendSIGHUP=</varname>). If processes still
  90         remain after the main process of a unit has exited or the delay configured via the
  91         <varname>TimeoutStopSec=</varname> has passed, the termination request is repeated with the
  92         <constant>SIGKILL</constant> signal or the signal specified via <varname>FinalKillSignal=</varname>
  93         (unless this is disabled via the <varname>SendSIGKILL=</varname> option). See
  94         <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry> for more
  95         information.</para>
  96
  97         <para>Defaults to <option>control-group</option>.</para></listitem>
  98       </varlistentry>
  99
 100       <varlistentry>
 101         <term><varname>KillSignal=</varname></term>
 102         <listitem><para>Specifies which signal to use when killing a
 103         service. This controls the signal that is sent as first step
 104         of shutting down a unit (see above), and is usually followed
 105         by <constant>SIGKILL</constant> (see above and below). For a
 106         list of valid signals, see
 107         <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 108         Defaults to <constant>SIGTERM</constant>. </para>
 109
 110         <para>Note that, right after sending the signal specified in
 111         this setting, systemd will always send
 112         <constant>SIGCONT</constant>, to ensure that even suspended
 113         tasks can be terminated cleanly.</para>
 114         </listitem>
 115       </varlistentry>
 116
 117       <varlistentry>
 118         <term><varname>SendSIGHUP=</varname></term>
 119         <listitem><para>Specifies whether to send
 120         <constant>SIGHUP</constant> to remaining processes immediately
 121         after sending the signal configured with
 122         <varname>KillSignal=</varname>. This is useful to indicate to
 123         shells and shell-like programs that their connection has been
 124         severed. Takes a boolean value. Defaults to "no".
 125         </para></listitem>
 126       </varlistentry>
 127
 128       <varlistentry>
 129         <term><varname>SendSIGKILL=</varname></term>
 130         <listitem><para>Specifies whether to send
 131         <constant>SIGKILL</constant> (or the signal specified by
 132         <varname>FinalKillSignal=</varname>) to remaining processes
 133         after a timeout, if the normal shutdown procedure left
 134         processes of the service around. When disabled, a
 135         <varname>KillMode=</varname> of <constant>control-group</constant>
 136         or <constant>mixed</constant> service will not restart if
 137         processes from prior services exist within the control group.
 138         Takes a boolean value. Defaults to "yes".
 139         </para></listitem>
 140       </varlistentry>
 141
 142       <varlistentry>
 143         <term><varname>FinalKillSignal=</varname></term>
 144         <listitem><para>Specifies which signal to send to remaining
 145         processes after a timeout if <varname>SendSIGKILL=</varname>
 146         is enabled. The signal configured here should be one that is
 147         not typically caught and processed by services (<constant>SIGTERM</constant>
 148         is not suitable). Developers can find it useful to use this to
 149         generate a coredump to troubleshoot why a service did not
 150         terminate upon receiving the initial <constant>SIGTERM</constant>
 151         signal. This can be achieved by configuring <varname>LimitCORE=</varname>
 152         and setting <varname>FinalKillSignal=</varname> to either
 153         <constant>SIGQUIT</constant> or <constant>SIGABRT</constant>
 154         Defaults to <constant>SIGKILL</constant>.
 155         </para></listitem>
 156       </varlistentry>
 157
 158       <varlistentry>
 159         <term><varname>WatchdogSignal=</varname></term>
 160         <listitem><para>Specifies which signal to use to terminate the
 161         service when the watchdog timeout expires (enabled through
 162         <varname>WatchdogSec=</varname>). Defaults to <constant>SIGABRT</constant>.
 163         </para></listitem>
 164       </varlistentry>
 165
 166     </variablelist>
 167   </refsect1>
 168
 169   <refsect1>
 170       <title>See Also</title>
 171       <para>
 172         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 173         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 174         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 175         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 176         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 177         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 178         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 179         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 180         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 181         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 182         <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 183         <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 184       </para>
 185   </refsect1>
 186
 187 </refentry>