If you're using Subversion during development (and you really should be using some kind of version control system), you can wire it up so that your development site will be updated automatically every time you commit a file. And it's easy!

Well, it's really easy if your subversion server and development web server is the same. If it's not, it's still possible, but outside of the scope of this article. You'll also want to be familiar with the command line, shell scripting and Subversion before attempting this stuff.

The first thing is to make sure your development server is a Subversion working copy, or in other words, that you can go into the dev site folder and run "svn update" to update the site. So if you've been using "svn export" or something painful like FTP, you may need to replace the dev site with a folder created using "svn checkout".

Okay, once you can update the dev site using Subversion, all you need to do is edit or create a file called "post-commit" inside the subversion repository, inside the "hooks" folder. If you look in that folder, there will probably be a bunch of example files like "post-commit.tmpl". These are examples of what you can do. Create the post-commit file by copying over the example, like "cp post-commit.tmpl post-commit", then edit this post-commit file.

Inside that file, there will be some example code like:

/usr/lib/subversion/hook-scripts/commit-email.pl "$REPOS" "$REV" commit-watchers@example.org

You'll want to remove or comment out this line and stick in your own scripting. You can put any commands in here that you want to run after each commit. For example, to update your dev site, you might have something like this:

cd /var/www/path/to/website
svn update >> /path/to/logfile

That's it!

If you run into problems and you used the logfile like in the example, you can have a look in there are see if there are any error messages. I often have problems with permissions, so you may want to change the permissions in the dev folder (eg. chmod 770 -R *).

This works really well when more than one person is working on a set of files. Instead of 7000 files like "file.html.backup_jesse_19-01-2008" you can just commit and see the changes instantly. It might seem annoying to have to commit files every time you make a change, but it's the same if not easier than uploading files over FTP every time.