Linux is using signal(SIGCHLD, SIG_IGN) which allows us to do nothing
  at all. This does not seem to be a POSIX standard. Does BSD happen to
  have this feature?

The default behavior for SIGCHLD is to discard the signal (says 'man 7
signal' on NetBSD 1.6.1).  So that call looks redundant.  Does
explicitly asking to ignore SIGCHLD mean that the process fully exits
without the parent wait()ing, and avoids the zombie state?  That
sounds, at first blush, like a POSIX violation.

        Greg Troxel <gdt_at_ir.bbn.com>