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From: Jerry McAllister <jerrymc@clunix.cl.msu.edu>
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To: friar_josh@tcbug.org (Josh Paetzel)
Date: Mon, 2 Aug 2004 10:48:52 -0400 (EDT)
In-Reply-To: <200408011829.58952.friar_josh@tcbug.org> from "Josh Paetzel" at
	Aug 01, 2004 06:29:58 PM
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cc: questions@freebsd.org
Subject: Re: Way OT programming question
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> 
> I've been muddling through some of the source files for FreeBSD 
> 5.2.1-RELEASE, and I've noticed that a large number of .c files 
> in /usr/src have something similar to below in them:
> 
> #ifndef lint
> #if 0
> static char sccsid[] = "@(#)cat.c       8.2 (Berkeley) 4/27/95";
> #endif
> #endif /* not lint */
> #include <sys/cdefs.h>
> __FBSDID("$FreeBSD: src/bin/cat/cat.c,v 1.29 2003/04/30 17:40:28 
> obrien Exp $");
> 
> 1) Isn't 'if 0' always negative?

In a boolean usage like above, yes.   Anyway, FALSE usually gets
defined to be 0.   So, the above piece of code is disabled - sort
of commented out, so to speak.

> 2) What is the __FBSDID line doing?

Looks like it sets or checks some version information.  Guess I could 
look it up, but then, so could you.

////jerry

> 
> -- 
> Thanks,
> 
> Josh Paetzel
> _______________________________________________