gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (11/30/84)
I couldn't find the original message about using signal 0 to determine whether a child process has terminated without doing a wait for it. Since then, friends have researched the issue, with the following result: signal 0 NOT SUPPORTED on 6th Edition UNIX, 7th Edition UNIX, nor 4.1BSD signal 0 SUPPORTED on UNIX System III, UNIX System V, Research Version 8, and 4.2BSD
rml@hpfcls.UUCP (rml) (12/16/84)
> I couldn't find the original message about using signal 0 to determine > whether a child process has terminated without doing a wait for it. > Since then, friends have researched the issue, with the following result: > > signal 0 NOT SUPPORTED on 6th Edition UNIX, 7th Edition UNIX, > nor 4.1BSD > > signal 0 SUPPORTED on UNIX System III, UNIX System V, Research > Version 8, and 4.2BSD Using signal 0 to determine whether a child process has terminated assumes that, when sending a signal to a zombie process, kill(2) returns an error. This is true in 4.2BSD, but not in System III or V (I have no idea about Research Version 8). Bob Lenk {hplabs, ihnp4}!hpfcla!rml