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Path: utzoo!watmath!clyde!cbosgd!ihnp4!mhuxn!mhuxr!ulysses!allegra!mit-eddie!godot!harvard!seismo!mcvax!boring!jack
From: jack@boring.UUCP
Newsgroups: net.unix-wizards,net.bugs.usg
Subject: Re: Shell out bug in pg (Actually: wait bug in V7 tar)
Message-ID: <6357@boring.UUCP>
Date: Fri, 15-Mar-85 08:42:36 EST
Article-I.D.: boring.6357
Posted: Fri Mar 15 08:42:36 1985
Date-Received: Sun, 17-Mar-85 00:37:19 EST
References: <12@istbt.UUCP> <562@rlgvax.UUCP> <9069@brl-tgr.ARPA> <127@hadron.UUCP>
Reply-To: jack@boring.UUCP (Jack Jansen)
Organization: CWI, Amsterdam
Lines: 23
Xref: watmath net.unix-wizards:12454 net.bugs.usg:194
Summary: 
Apparently-To: rnews@mcvax.LOCAL


Well, for the benefit of all V7 users that are still out there:
There is a bug like this in Version 7 tar.
When it has to make a new directory, it does something like

	if( fork() == 0) {
		exec("/bin/mkdir",....)
		exit();
	}
	while( wait(NULL) > 0 );	<--- GRRRRR

Now, guess what happens when you start up tar in the receiving
end of a pipe.......

(For those who don't like guessing: The shell sets up pipes so
that the front end is a child of the back end. This means that,
besides the mkdir, tar will have another child, being the first
end of the pipe. This means that the second wait will take a
*very* long time........)

-- 
	Jack Jansen, {decvax|philabs|seismo}!mcvax!jack
It's wrong to wish on space hardware.