From: Paul Brannan <pbrannan@...>
Date: 2001-06-23T05:36:49+09:00
Subject: [ruby-talk:16781] Re: socket bug

> Thanks, that helped a lot.  This seems to do the trick:
> trap("CHLD", "SIG_IGN")

Note that this is disallowed by POSIX.  SIGCHLD is the signal that causes
the parent to clean up children that have terminated.  Ignoring SIGCHLD
could, on some systems, cause a bunch of zombie processes (since they
won't get cleaned up).  From the Linux man page for signal(2):

    According to POSIX (B.3.3.1.3) you must not set the action
    for SIGCHLD to SIG_IGN.  Here the BSD and SYSV  behaviours
    differ,  causing  BSD  software  that  sets the action for
    SIGCHLD to SIG_IGN to fail on Linux.

Susv2 does specify that no children are to become zombies when SIGCHLD is
ignored, but it's best not to depend on the behaviour of ignoring SIGCHLD.

Paul