Odd shell behaviour

From: Alain G. (agrumela_at_nospamfoxboro.ca)
Date: 09/01/04 

Date: Tue, 31 Aug 2004 21:07:32 -0400

I have used the following shell sequence without any problems
on a number of application running on Solaris 5.

    #! /bin/sh

    sleep 999 & pid=$!
    myprogr-syncpid $pid &
    wait $pid

The idea is to suspend execution of the shell script until
myprog has finished its initialization.
myprog kills the sleep process using the $pid argument when
it is ready and wait unblocks.

I recently tried to use the same scheme on Solaris 8 and found
it fails occasionally (not always).
The shell does not suspend on wait and sleep lives on until the time
expires.
As far as I can tell, this fails because $! returns the pid of a sub-shell
rather
than the pid of the sleep process.

The sh man pages says that the the shell will execute a command in a
sub-shell
if the command's executable file is not an a.out type of file.
Yet when I check "which sleep" I find that it is /usr/bin/sleep and
file /usr/bin/sleep reports that it is a regular executable file for that
platform
which I believe is the same as an a.out file.

Is there anyone who can offer any explanation why this is happenning?

Thanks

AL.

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