I have a bunch of pages from a forum that I want to redirect, which look like this:

Redirect 301 /forum/viewtopic.php?f=3&t=16 http://www.samewebsite.com/newurl

I tried putting that (and about 15 more lines) in a .htaccess file, but none of the redirects work.

From the reading I've been doing, I think the problem might be the fact that the pages (forum threads) are specified by the variables in the URL. Is that the problem? What should I do?

Thanks!

And do you want them all to go to the same URL?

No, unfortunately they go to different URLs.

and the patterns to match for the target pages?

I'm sorry, I'm really illiterate when it comes to this server admin stuff. What do you mean by patterns to match?

There are no variables in the new URLs, if that's what you're asking. The new pages are scattered throughout different directories and have no similarities.

ex.

Redirect 301 /forum/viewtopic.php?f=3&t=16 http://www.samewebsite.com/a/new/dir/page1
Redirect 301 /forum/viewtopic.php?f=5&t=2 http://www.samewebsite.com/another/dir/filename
Redirect 301 /forum/viewtopic.php?f=1&t=99 http://www.samewebsite.com/yet/another/one

See this thread (post #6 onwards), a "smart 404" might be more in order.

Assuming that viewtopic no longer exists.

Yes, the viewtopic page no longer exists..

Skimming the thread you linked to, are you saying that the easiest solution would be to create a custom 404 page which checks the URL and, if it's one that needs to be redirected, redirect the page?

It works for me on modtalk.co.uk.

It's also a more "server friendly" solution than several lines of htaccess directives that have to be checked on every request.