Strange behaviour from jobs -p in a subshell

[Christopher Jefferson]

Consider the following script. While the 3 sleeps are running, both jobs 
-p and $(jobs -p) will print 3 PIDs. Once the 3 children are finished, 
jobs -p will continue to print the 3 PIDs of the done Children, but 
$(jobs -p) will only print 1 PID. $(jobs -p) always seems to print at 
most 1 PID of a done child.


#!/usr/bin/bash

(sleep 2 ) &
(sleep 2 ) &
(sleep 2 ) &

while /bin/true
do
     echo A
     echo $(jobs -p)
     echo B
     jobs -p
     echo C
     sleep 1
done