This had me pulling my hair out yesterday, so I thought I'd share the experience with enough key terms that the next person pulling their hair out will find it.

I was installing my CMS software on a work machine. I'll likely be doing additional development on it, and the university is the best place to do this. But that's neither here nor there. My software is designed around 'clean URLs'; which means what you see in the URL bar isn't (usually) littered with code and operating system artifacts. So for instance to post to my weblog, I go to the URL /post/weblog, not something like post.php?op=weblog.

To accomplish this, I use an Apache webserver module called 'mod_rewrite', which takes care of the nitty details of this process. Mod_rewrite is not without its faults, but that's the subject of another article. It does the job. The biggest thing it does is let you leave out the '.php', except I'm letting it do a whole lot more.

Anyway I'll cut to the chase. My software was horribly broken after installing it yesterday. It took hours to figure out why. Something else was trying to provide clean URLs and strip '.php' from places where I actually needed to have it in order for things to work. Well that's not technically correct either. It was actually executing PHP files by URL without the extension. Except that these were 'include files'. They weren't meant to be executed directly. They were meant to be included in something else, and the something else was managed by mod_rewrite. The something else was never getting called. 

This was inconceivable. Nothing in any of the system release notes said anything about some magic new clean URL ability. This was on Debian (edge). Apache, PHP, MySQL. I tried all the sites. I googled for everything I could think of. Clean URL debian. Clean url apache. '.php not needed'. mod_rewrite. strip file extension. ForceType. (ForceType also lets you execute files without providing a filename extension). I scoured the last several months of Apache release notes, to no avail.

Finally after several hours I happened upon a little gem of a snippet on an obscure website. 'Turn on Multiviews instead of ForceType'. Debian has multiviews turned on by default, but this is the first I'd heard of it. I had assumed (never do this of course) that it was yet another fancy mod_dir option or something I didn't care about.

No. Multiviews is a slick trick for Apache that takes any pathname, and if it thinks it can find a page to return, it returns it. It uses the basename of the file in the URL and if there's no file, it looks for the filename with an extension. Any extension. Then it sends the file back. So it gives you a clean URL. You type in 'index' and it will send back 'index.htm' or 'index.html' or 'index.php' or 'index.pl' or 'index.shtml'. You get the idea. You can test this on any site that has multiviews turned on by asking for 'index' and see if you actually get a page. Normally you wouldn't. 

If the URL is 'post' and there's a file in the directory called 'post.php' it will send that file back even if you don't want it to. So I'll let you research it further if multiviews is what you want. It's actually pretty cool. In my case I had to disable it.

Options -Multiviews in the .htaccess did the trick and made everything work again.