man/systemd.kill.xml

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   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 killed. One of
  65         <option>control-group</option>, <option>mixed</option>, <option>process</option>,
  66         <option>none</option>.</para>
  67
  68         <para>If set to <option>control-group</option>, all remaining processes in the control group of this
  69         unit will be killed on unit stop (for services: after the stop command is executed, as configured
  70         with <varname>ExecStop=</varname>). If set to <option>mixed</option>, the
  71         <constant>SIGTERM</constant> signal (see below) is sent to the main process while the subsequent
  72         <constant>SIGKILL</constant> signal (see below) is sent to all remaining processes of the unit's
  73         control group. If set to <option>process</option>, only the main process itself is killed (not
  74         recommended!). If set to <option>none</option>, no process is killed (strongly recommended
  75         against!). In this case, only the stop command will be executed on unit stop, but no process will be
  76         killed otherwise.  Processes remaining alive after stop are left in their control group and the
  77         control group continues to exist after stop unless empty.</para>
  78
  79         <para>Note that it is not recommended to set <varname>KillMode=</varname> to
  80         <constant>process</constant> or even <constant>none</constant>, as this allows processes to escape
  81         the service manager's lifecycle and resource management, and to remain running even while their
  82         service is considered stopped and is assumed to not consume any resources.</para>
  83
  84         <para>Processes will first be terminated via <constant>SIGTERM</constant> (unless the signal to send
  85         is changed via <varname>KillSignal=</varname> or <varname>RestartKillSignal=</varname>). Optionally,
  86         this is immediately followed by a <constant>SIGHUP</constant> (if enabled with
  87         <varname>SendSIGHUP=</varname>). If processes still remain after the main process of a unit has
  88         exited or the delay configured via the <varname>TimeoutStopSec=</varname> has passed, the termination
  89         request is repeated with the <constant>SIGKILL</constant> signal or the signal specified via
  90         <varname>FinalKillSignal=</varname> (unless this is disabled via the <varname>SendSIGKILL=</varname>
  91         option). See <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
  92         for more information.</para>
  93
  94         <para>Defaults to <option>control-group</option>.</para></listitem>
  95       </varlistentry>
  96
  97       <varlistentry>
  98         <term><varname>KillSignal=</varname></term>
  99         <listitem><para>Specifies which signal to use when stopping a service. This controls the signal that
 100         is sent as first step of shutting down a unit (see above), and is usually followed by
 101         <constant>SIGKILL</constant> (see above and below). For a list of valid signals, see
 102         <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 103         Defaults to <constant>SIGTERM</constant>.</para>
 104
 105         <para>Note that, right after sending the signal specified in this setting, systemd will always send
 106         <constant>SIGCONT</constant>, to ensure that even suspended tasks can be terminated cleanly.</para>
 107         </listitem>
 108       </varlistentry>
 109
 110       <varlistentry>
 111         <term><varname>RestartKillSignal=</varname></term>
 112         <listitem><para>Specifies which signal to use when restarting a service. The same as
 113         <varname>KillSignal=</varname> described above, with the exception that this setting is used in a
 114         restart job. Not set by default, and the value of <varname>KillSignal=</varname> is used.</para>
 115         </listitem>
 116       </varlistentry>
 117
 118       <varlistentry>
 119         <term><varname>SendSIGHUP=</varname></term>
 120         <listitem><para>Specifies whether to send
 121         <constant>SIGHUP</constant> to remaining processes immediately
 122         after sending the signal configured with
 123         <varname>KillSignal=</varname>. This is useful to indicate to
 124         shells and shell-like programs that their connection has been
 125         severed. Takes a boolean value. Defaults to "no".
 126         </para></listitem>
 127       </varlistentry>
 128
 129       <varlistentry>
 130         <term><varname>SendSIGKILL=</varname></term>
 131         <listitem><para>Specifies whether to send
 132         <constant>SIGKILL</constant> (or the signal specified by
 133         <varname>FinalKillSignal=</varname>) to remaining processes
 134         after a timeout, if the normal shutdown procedure left
 135         processes of the service around. When disabled, a
 136         <varname>KillMode=</varname> of <constant>control-group</constant>
 137         or <constant>mixed</constant> service will not restart if
 138         processes from prior services exist within the control group.
 139         Takes a boolean value. Defaults to "yes".
 140         </para></listitem>
 141       </varlistentry>
 142
 143       <varlistentry>
 144         <term><varname>FinalKillSignal=</varname></term>
 145         <listitem><para>Specifies which signal to send to remaining
 146         processes after a timeout if <varname>SendSIGKILL=</varname>
 147         is enabled. The signal configured here should be one that is
 148         not typically caught and processed by services (<constant>SIGTERM</constant>
 149         is not suitable). Developers can find it useful to use this to
 150         generate a coredump to troubleshoot why a service did not
 151         terminate upon receiving the initial <constant>SIGTERM</constant>
 152         signal. This can be achieved by configuring <varname>LimitCORE=</varname>
 153         and setting <varname>FinalKillSignal=</varname> to either
 154         <constant>SIGQUIT</constant> or <constant>SIGABRT</constant>.
 155         Defaults to <constant>SIGKILL</constant>.
 156         </para></listitem>
 157       </varlistentry>
 158
 159       <varlistentry>
 160         <term><varname>WatchdogSignal=</varname></term>
 161         <listitem><para>Specifies which signal to use to terminate the
 162         service when the watchdog timeout expires (enabled through
 163         <varname>WatchdogSec=</varname>). Defaults to <constant>SIGABRT</constant>.
 164         </para></listitem>
 165       </varlistentry>
 166
 167     </variablelist>
 168   </refsect1>
 169
 170   <refsect1>
 171       <title>See Also</title>
 172       <para>
 173         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 174         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 175         <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 176         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 177         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 178         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 179         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 180         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 181         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 182         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 183         <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
 184         <citerefentry project='man-pages'><refentrytitle>signal</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 185       </para>
 186   </refsect1>
 187
 188 </refentry>