run on shells

[utzoo!decvax!ucbvax!menlo70!sri-unix!ihnss!warren at Berkeley]

If you are running a version of unix that implements the SIGCLD
signal (#18), the problem may be that the daemon invoking the shell
explicitly ignores it.  This causes sub-processes that terminate to
vanish without a trace, never returning their process id as a result
of a wait() in their parent.  The bourne shell, unfortunately,
expects to see its children terminate and will go into a loop
calling wait with no outstanding descendants if this does not
happen.  I suspect that SIGCLD and its strange effect on wait were
not foreseen when the shell was written, and as a result the signal
is not initialized properly by it.

	Warren Montgomery
	ihnss!warren
	IH x2494