Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!watmath!clyde!burl!ulysses!allegra!mit-eddie!think!harvard!caip!nike!styx!lll-crg!gymble!umcp-cs!seismo!mcvax!ukc!hrc63!nwh
From: nwh@hrc63.UUCP (Nigel Holder Marconi)
Newsgroups: net.unix-wizards
Subject: System V and SIGCLD
Message-ID: <344@hrc63.UUCP>
Date: Fri, 9-May-86 05:07:52 EDT
Article-I.D.: hrc63.344
Posted: Fri May  9 05:07:52 1986
Date-Received: Tue, 13-May-86 01:08:24 EDT
Organization: GEC Hirst Research Labs, Wembley, Middlesex.
Lines: 27


   The problem with resetng SIGCLD is that the signal is still valid since
the child process is waiting for the parent to perform a wait.  The following
implements this and of course works !



	trap(sig)

	int	sig;

	{
		int	c;

		printf("trapped SIGCLD\n");
		wait(&c);
		signal(SIGCLD, trap);	/* reset handler */
	}


   Now that brings me to wait.  4.2 at least provides two flavours of wait :
wait and wait3.  Now wait3 is new and is free to do what it wants in its own
way.   Wait however, does not requires an int pointer, it requires a pointer
to a union which happens to start with an int.  Whether this affects
programs written in Sys V flavour or not is probably well defined at the
moment, but it could change.  Just another example of a transparent
difference between flavours that is easily overlooked.