[TerryP]

more or less yeah, that's the example case I was using ephemera.

As to your example, except if one doesn't want the parent to pop a cork when the sub shell closes, something like this might be more appropriate:

ALIVE=1
command="sleep 5"       # lengthy processing program
trap 'ALIVE=0' TERM
printf "running \"$command\" ";
($command; printf " finished with exitcode=$?\n"; kill $$)&
while [ $ALIVE -gt 0 ]; do printf .; sleep 1; done
echo continue with other work when child is done

you could say, the idea of a fork built in would be to say something like, "setup the trap for me"


or to rewrite the original (fork) example with trap:

# a super simple but conceptual example

# a variable to communicate status between child/parent
ALIVE=1
trap 'ALIVE=0' TERM

if [ $? -ne 0 ]; then
    # Note: if trap ever errors out beyond syntax errors
    #     I never check the exit status of trap in my
           own scripts
    echo "$0: Unable to trap SIGTERM for ..., stopping $0"
    exit 255
else
    echo "doing processing: ... whatever"

    (do lengthy processing in child; kill $$) &

    # when the child exits, the variable becomes false (and exits the loop)
    while [ $ALIVE -gt 0 ]; do
        printf '.'; sleep 1
    done
    echo 'done processing'
fi

(this reminds me, making key bindings in ksh93 is a fun)