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Killing an Xterm while leaving subprocess alive...

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Old 10-21-2005
Killing an Xterm while leaving subprocess alive...
Hi,
I'm not quite understanding what I'm doing (happens often). This pseudocode works:

#!/bin/pseudoksh

function kill_parent {
when i_want_to ; do
sleep 2
kill -TERM $PPID
exit
done
}

kill_parent &
ssh remote_host sh <<-EOF
notify_kill_parent # let the bg function know it's ok to kill parent
run_command # something x-based
EOF


Now, if I start my script in an xterm:
xterm -e run_my_script
It works as expected! The xterm pops up, ssh queries me for a password, the command runs and displays, and, seconds later, the xterm is killed. This is what I want to have happen. But I'm not sure why the remote shell and my application (run_command, above) still stick around. I've been pretty sloppy with stdin/stdout so I'm surprised they don't disappear when I kill the parent (xterm).

I'm happy it works, but I'm worried about a bug creeping in later- for example, since I'm not handling stdout, am I in danger of filling a buffer that is going to make the app hang? Or something like this.

I'm looking for insight into what happens when xterm calls ssh which calls a shell which calls a command. Xterm dies but the command does not. Why?
Thanks.
-Schwage
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LEARN ABOUT NETBSD

kill

KILL(1) 						    BSD General Commands Manual 						   KILL(1)

NAME

     kill -- terminate or signal a process

SYNOPSIS

     kill [-s signal_name] pid ...
     kill -l [exit_status]
     kill -signal_name pid ...
     kill -signal_number pid ...

DESCRIPTION

     The kill utility sends a signal to the process(es) specified by the pid operand(s).

     Only the super-user may send signals to other users' processes.

     The options are as follows:

     -s signal_name
	     A symbolic signal name specifying the signal to be sent instead of the default TERM.

     -l [exit_status]
	     Display the name of the signal corresponding to exit_status.  exit_status may be the exit status of a command killed by a signal (see
	     the special sh(1) parameter '?') or a signal number.

	     If no operand is given, display the names of all the signals.

     -signal_name
	     A symbolic signal name specifying the signal to be sent instead of the default TERM.

     -signal_number
	     A non-negative decimal integer, specifying the signal to be sent instead of the default TERM.

     The following pids have special meanings:
     -1      If superuser, broadcast the signal to all processes; otherwise broadcast to all processes belonging to the user.
     0	     Broadcast the signal to all processes in the current process group belonging to the user.

     Some of the more commonly used signals:
     1	     HUP (hang up)
     2	     INT (interrupt)
     3	     QUIT (quit)
     6	     ABRT (abort)
     9	     KILL (non-catchable, non-ignorable kill)
     14      ALRM (alarm clock)
     15      TERM (software termination signal)

     kill is a built-in to csh(1); it allows job specifiers of the form ``%...'' as arguments so process id's are not as often used as kill argu-
     ments.  See csh(1) for details.

SEE ALSO

     csh(1), pgrep(1), pkill(1), ps(1), kill(2), sigaction(2), signal(7)

STANDARDS

     The kill function is expected to be IEEE Std 1003.2 (``POSIX.2'') compatible.

HISTORY

     A kill command appeared in Version 6 AT&T UNIX.

BSD
								  April 28, 1995							       BSD