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Full Discussion: [KSH/Bash] Starting a parent process from a child process?
Top Forums Shell Programming and Scripting [KSH/Bash] Starting a parent process from a child process? Post 302408518 by bakunin on Monday 29th of March 2010 06:42:44 PM
Old 03-29-2010
Quote:
Originally Posted by alister
The death of a process, even a parent process, does not trigger the kernel to send SIGHUP to any processes.
OK, now i understand, where you come from. We misunderstood each other, because we were talking about different things. In ksh it is standard that SIGHUP is sent to any child process in background once the father process gets killed. If script A calls script B by a line like "b.sh &" B will be terminated once A is killed. (I believe this is a main difference to the BASH shell, which handles the case differently.) Using a line like "nohup b.sh &" would prevent B from being killed if A is terminated.

Yes, this behavior is not necessarily the same for processes in general, as you have correctly pointed out. In (Korn) shell programming and for processes created by the ksh this is the case though.

bakunin
 

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LEARN ABOUT ULTRIX

systemd.kill

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, process, mixed, 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 process, only the main process itself is killed. 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 none, no process is killed. In this case, only the stop command will be executed on
	   unit stop, but no process be killed otherwise. Processes remaining alive after stop are left in their control group and the control
	   group continues to exist after stop unless it is empty.

	   Processes will first be terminated via SIGTERM (unless the signal to send is changed via KillSignal=). Optionally, this is immediately
	   followed by a SIGHUP (if enabled with SendSIGHUP=). If then, after a delay (configured via the TimeoutStopSec= option), processes still
	   remain, the termination request is repeated with the SIGKILL signal (unless this is disabled via the SendSIGKILL= option). See kill(2)
	   for more information.

	   Defaults to control-group.

       KillSignal=
	   Specifies which signal to use when killing 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.

       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".

       SendSIGKILL=
	   Specifies whether to send SIGKILL to remaining processes after a timeout, if the normal shutdown procedure left processes of the
	   service around. Takes a boolean value. Defaults to "yes".

SEE ALSO

       systemd(1), systemctl(1), journalctl(8), 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 237															   SYSTEMD.KILL(5)
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