NetNews Usenet Archive 1992 #19/NN_1992_19.iso/spool/comp/unix/xenix/sco/2744

Internet Message Format | 1992-08-25 | 1.7 KB

Path: sparky!uunet!portal!cup.portal.com!compata
From: [e-mail] (David H Close)
Newsgroups: comp.unix.xenix.sco
Subject: Keep-alive watchdog for shell process
Message-ID: <[e-mail]>
Date: Wed, 26 Aug 92 02:33:15 PDT
Organization: The Portal System (TM)
Distribution: world
Lines: 24

It may not be relevant but this system is SCO Xenix 386 2.3.3 with xnx296.
My question relates to a fairly generic shell process, probably similar for
all known flavors of Unix.

Does anyone know of a way to make a shell process dependent upon the
periodic receipt of a "keep-alive" signal?  Of course, I mean through the
use of the standard set of shell commands and system utilities.  That is,
without programming except in sh, is there a way to make a shell process
die if it doesn't receive some signal at regular intervals?

A first look at TFM reveals that alarm(S) has no counterpart in (C), at
least that I can see.  If wrapped in a simple C program, alarm() would
still not work as that program would not run in the shell's process.  So,
I suspect that two cooperating but independent processes will be needed.
The extra one would receive the periodic signals, resetting its own alarm
each time.  If one failed to arrive and the alarm was triggered, the main
process would be signalled.  But I can't see any way to write this extra
process entirely in sh (or ksh for that matter).

Of course, if there isn't a way, I'd also appreciate any pointers to a
simple program that could do the job.  Thanks for your consideration.

 Dave Close - Compata - Stockton, California - [phone] ("209-install")
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