Detecting running processes... this one's portable

[Brandon Allbery]

Expires:

Quoted from <212 at amc.UUCP> ["Re: csh-script to run a job after an existing job terminates"], by stan at amc.UUCP (Stan Tazuma)...
+---------------
| In article <515 at cubsvax.UUCP> peters at cubsvax.UUCP (Peter S. Shenkin) writes:
| >DESCRIPTION:
| >after:	a procedure that waits until a particular running process terminates, 
| >	then initiates a new process.  This runs under csh, but should be
| >	easily translatable to bsh or ksh.
| >
| I think it's a useful tool, but there are simpler ways to do it (at
| least under a BSD Unix (which includes the Ultrix you're using)).
| Here's a program I came up with a while back.  It's called waitp.
| It has the same args. as "after".
| ------------waitp.c------------
| For AT&T Unix versions, getpgrp() doesn't behave in the above way (waitp.c).
| The AT&T ps command can be used to look at a specific process, though
| using a different ps argument than above.
+---------------

I have another method; it works everywhere except that under System V it
doesn't work to see if a process has exited and should be waited upon (this
doesn't apply to an ``after'' program anyway):

--------
#! /bin/sh
while kill -0 ${1-?}; do
	sleep ${2-60}
done
--------

The C version is just as trivial.  Note that kill -0 isn't documented in V7 or
System III... then again, V7 didn't have getpgrp() that I saw, so neither
method will work.

++Brandon
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