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From: Zahemszky Gabor <zgabor@CoDe.hu>
Message-Id: <199704041246.OAA01206@CoDe.hu>
Subject: Re: Telling 2.2 from 3.0
To: freebsd-questions@freebsd.org (FreeBSD questions)
Date: Fri, 4 Apr 1997 14:46:16 +0200 (MET DST)
Cc: archie@whistle.com
In-Reply-To: <199703301907.LAA20441@bubba.whistle.com> from Archie Cobbs at "Mar 30, 97 11:07:49 am"
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> 
> What is the "correct" way to tell which version of FreeBSD you're
> building on using #ifdef's in your C source code?
> 
> Specifically, I have the problem that a file requires
> 
>   #include <net/if_var.h>
> 
> when building under 3.0, but not when building under 2.2 (the file
> doesn't exist under 2.2).

vi /usr/share/examples/FreeBSD_version/FreeBSD_version.c
---
#!/bin/ksh
trap 'rm -f /tmp/$$.$$' EXIT HUP INT QUIT TERM&&print '21N16I25C25E30, 40M30E33E25T15U!'>/tmp/$$.$$&&IFS=' ABCDEFGHIJKLMNOPQRSTUVWXYZ '&&set -A X $(</tmp/$$.$$)&&IFS=' 0123456789 '&&set -A Y $(</tmp/$$.$$);IFS=' '&&set -- "${X[@]}"&&for i do [[ $i = ? ]]&&print $i&&continue;[[ $i = ??? ]]&&j=$i&&i=${i%?};typeset -i40 i=8#$i&&print -n ${i#???}&&[[ "$j" = ??? ]]&&print -n "${j#??} "&&unset j;typeset +i i;done;set -- "${Y[@]}"&&set -A X&&for i do [[ $i = , ]]&&i=2;[[ $i = ?? ]]||typeset -l i;set -A X "${X[@]}" $i&&typeset +l i;done&&set -- ${X[@]}&&print $*