In this document, I'm going to use phpBB2 as an example. Everything here, should be applicable for any PHP site - or with a little rewriting of the code fragments, for anything that is processed on the server-side :)
Well - let's start with the apache setup:
converting
http://yoursite.tld/viewforum.php/f/14.html
to original url (minus the sid - see below):
http://yoursite.tld/viewforum.php?f=14&sid=0d48ecb4e79d1ksl653661d849983ec6
the rewriterule would look like this (untested - I don't have phpBB2 running as standalone - but you could test it without harming anyone):
# this handles /*.php?somevar=somedigit
RewriteRule (.*)/([A-Za-z]+)\.php/([A-Za-z]+)/([0-9]+).html$ $1/$2.php?$3=$4 [L,NC,NS]
# Then we could add rewriteurl's to handle the extra options one can add - like
# highlight and stuff - but seeing as this is for google benefit - I don't see
# the need to right now :)
The sid part is only on the forum links - not the individual topic links.
I tested it without the sid - and it works just fine. AFAIK we can safely ignore the sid (ie. when rewriting urls on the way out) - otherwise there's a fix here: http://www.phpbb.com/phpBB/viewtopic.php?t=32328&highlight=sid+cookie that will leave out the sid - only for googlebot :) which should be enough to get google to index the site.
Now for getting the url's rewritten so the browser(s) gets the correct url's.
I use a header and a footer-file to do my url-rewriting. I based this solution on source is the simpleurl scripts available for PostNuke - rewritten by me to fit this purpose.
. You could just include the header and footer file, by setting these two options in your php.ini:
auto_prepend_file="/path/to/header.php"
auto_append_file="/path/to/footer.php"
header:
call ob_start();
output whatever you want to - ie. run phpbb script as usual (if you add the header/footer to php.ini - you don't need to do anything - php will call whatever script was requested for you).
footer:
$contents = ob_get_contents();
ob_end_clean();
echo simplifyurls();
function simplify_urls(&$s) {
// stuff to add subdir prefixes
// - don't know how that works in straight phpBB2 - so it's commented out.
//$base_url = pnGetBaseURL();
//$prefix = '|"(?:'.$base_url.')?';
$prefix = '';
// (?i) means case insensitive; \w='word' character; \d=digit; (amp;)? means optional; (?:catid=)? means optional and won't capture string for backreferences
// NB. The first in array is replaced with the first out array line.
// first array should match viewforum.php?f=(1-8 digits) with or without &(with or without amp; after)sid=(alphanumeric chars until end of line).
// The second line shouldn be necessary if the first one works as planned - but only some testing will see :)
$in = array(
$prefix . 'viewforum.php\?f=((\d)(?:&(?:amp;)?sid=[0-9a-zA-Z]+?"|',
$prefix . 'viewforum.php\?f=((\d)"|',
$prefix . 'viewtopic.php\?t=((\d)"|'
);
$out = array(
'"viewforum.php/f/$1.html"',
'"viewforum.php/f/$1.html"',
'"viewtopic.php/t/$1.html"'
);
$s = preg_replace($in, $out, $s);
return $s;
}