SYSTEMD.KILL(5) systemd.kill SYSTEMD.KILL(5)
NAME
systemd.kill - Process killing procedure configuration
SYNOPSIS
service.service, socket.socket, mount.mount, swap.swap, scope.scope
DESCRIPTION
Unit configuration files for services, sockets, mount points, swap
devices and scopes share a subset of configuration options which define
the killing procedure of processes belonging to the unit.
This man page lists the configuration options shared by these five unit
types. See systemd.unit(5) for the common options shared by all unit
configuration files, and systemd.service(5), systemd.socket(5),
systemd.swap(5), systemd.mount(5) and systemd.scope(5) for more
information on the configuration file options specific to each unit
type.
The kill procedure configuration options are configured in the
[Service], [Socket], [Mount] or [Swap] section, depending on the unit
type.
OPTIONS
KillMode=
Specifies how processes of this unit shall be killed. One of
control-group, mixed, process, none.
If set to control-group, all remaining processes in the control
group of this unit will be killed on unit stop (for services: after
the stop command is executed, as configured with ExecStop=). If set
to mixed, the SIGTERM signal (see below) is sent to the main process
while the subsequent SIGKILL signal (see below) is sent to all
remaining processes of the unit's control group. If set to process,
only the main process itself is killed (not recommended!). If set to
none, no process is killed (strongly recommended against!). In this
case, only the stop command will be executed on unit stop, but no
process will be killed otherwise. Processes remaining alive after
stop are left in their control group and the control group continues
to exist after stop unless empty.
Note that it is not recommended to set KillMode= to process or even
none, as this allows processes to escape the service manager's
lifecycle and resource management, and to remain running even while
their service is considered stopped and is assumed to not consume
any resources.
Processes will first be terminated via SIGTERM (unless the signal to
send is changed via KillSignal= or RestartKillSignal=). Optionally,
this is immediately followed by a SIGHUP (if enabled with
SendSIGHUP=). If processes still remain after:
• the main process of a unit has exited (applies to KillMode=:
mixed)
• the delay configured via the TimeoutStopSec= has passed (applies
to KillMode=: control-group, mixed, process)
the termination request is repeated with the SIGKILL signal or the
signal specified via FinalKillSignal= (unless this is disabled via
the SendSIGKILL= option). See kill(2) for more information.
Defaults to control-group.
Added in version 187.
KillSignal=
Specifies which signal to use when stopping a service. This controls
the signal that is sent as first step of shutting down a unit (see
above), and is usually followed by SIGKILL (see above and below).
For a list of valid signals, see signal(7). Defaults to SIGTERM.
Note that, right after sending the signal specified in this setting,
systemd will always send SIGCONT, to ensure that even suspended
tasks can be terminated cleanly.
Added in version 187.
RestartKillSignal=
Specifies which signal to use when restarting a service. The same as
KillSignal= described above, with the exception that this setting is
used in a restart job. Not set by default, and the value of
KillSignal= is used.
Added in version 244.
SendSIGHUP=
Specifies whether to send SIGHUP to remaining processes immediately
after sending the signal configured with KillSignal=. This is useful
to indicate to shells and shell-like programs that their connection
has been severed. Takes a boolean value. Defaults to "no".
Added in version 207.
SendSIGKILL=
Specifies whether to send SIGKILL (or the signal specified by
FinalKillSignal=) to remaining processes after a timeout, if the
normal shutdown procedure left processes of the service around. When
disabled, a KillMode= of control-group or mixed service will not
restart if processes from prior services exist within the control
group. Takes a boolean value. Defaults to "yes".
Added in version 187.
FinalKillSignal=
Specifies which signal to send to remaining processes after a
timeout if SendSIGKILL= is enabled. The signal configured here
should be one that is not typically caught and processed by services
(SIGTERM is not suitable). Developers can find it useful to use this
to generate a coredump to troubleshoot why a service did not
terminate upon receiving the initial SIGTERM signal. This can be
achieved by configuring LimitCORE= and setting FinalKillSignal= to
either SIGQUIT or SIGABRT. Defaults to SIGKILL.
Added in version 240.
WatchdogSignal=
Specifies which signal to use to terminate the service when the
watchdog timeout expires (enabled through WatchdogSec=). Defaults to
SIGABRT.
Added in version 240.
SEE ALSO
systemd(1), systemctl(1), journalctl(1), systemd.unit(5),
systemd.service(5), systemd.socket(5), systemd.swap(5),
systemd.mount(5), systemd.exec(5), systemd.directives(7), kill(2),
signal(7)
systemd 257.9 SYSTEMD.KILL(5)
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