that has terminated (either because it has been killed by a
signal or because it has called
exit()) and whose
parentprocess has not yet received notification of its termination
consumes no other resources. This entry is retained to hold
the child's exit status until the parent process wants to
retrieve it. The parent can also be notified asynchronously
via a signal of the child's termination.
Zombie processes can be seen in "ps" listings occasionally
(with a status "Z" in some versions).
(1997-10-08)