Virtual Multiblog for WordPress

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Announcement: Virtual Multiblog is now on GitHub.

Greetings and salutations.

This is my second blog, which is here to serve as a repository for the really die-hard geekery that I feel just doesn’t belong in my regular blog. When I realized the need for a second blog, installing it ended up being a longer process than i anticipated, and I thought I would share the fruits of my experience.

Let me step back for a moment. I am a true hacker at heart, in the traditional sense: I love to pull things apart and take a look. To see how they work and how they might work better. I’m also an avid Mac-head, and since the rise of OS X, I’ve been learning the ins and outs of its Unix-like underbelly.

In a nutshell, my computer is highly customized.

A few years back I got a second computer — a laptop — and quickly discovered that while keeping one computer tweaked to prime operation just the way I like it is kind of fun, trying to keep two computers in such a state, and relatively synchronized, is a frustrating exercise in futility.

I also know a good bit of web coding. As I’ve been working with WordPress for a couple years now, I’ve come across a number of good plugins and expansions along the way. Beyond issues involved with installing them, (which is admittedly pretty easy, usually) over time I have to keep up with updates to these — not to mention updates to WordPress itself. From time to time I even delve into the plugin files myself and make improvements….

And I want to put in a second blog? Am I nuts??? Thinking of what a pain it would be to maintain two copies of WordPress, I started looking into the various multi-blog solutions people have come up with. Most of them involve a lot of weird modifications to several files and basically comprise major modifications to large swaths of the WordPress code that are fundamentally incompatible with the regular version.

I am a great fan of what I consider “elegant” coding, which means that the designer does his job with the simplest and most straightforward methodology possible. And I found a very elegant solution to the “multiple blog on one install” question. Allan Mertner came up with something that blew me away with its simplicity and power.

WordPress holds all of its data in a MySQL database, and there is a single file called wp-config.php that holds the database login information. Allan looked at this and realized that if you can change that one file, you can completely replace the blog. With this key realization he came up with a cunningly straightforward multi-blog system:

  1. Replace the standard wp-config.php file with a new version that calls a different configuration set depending on what directory it’s in.
  2. Set up symbolic links that serve as “virtual directories” that all point to the WordPress directory.

Using the example of this site, I have an install of WordPress in the root web directory, and a symbolic link called “nerdaphernalia” (that’s right, you’re soaking in it!) that points back to the root. The modified wp-config file points to either the default or nerdaphernalia config file, depending on which of those two directories it thinks it’s in.

So other than a happy user, where do I come in in all this? Well, I made a number of improvements. First, Allan’s system was great, but it required us to install various files in and around the core WordPress files, which for me at least defeats part of the purpose of using a multiblog system in the first place. I’m trying to make updates easier, remember? Updating WordPress generally involves deleting everything but the wp-config.php file and the wp-content folder, and then dropping in the new versions of everything else; but if there are important but non-standard files strewn about, I can’t just do that. I have to remember to go through and preserve those files, and then replace them when they’re done. Add in a few plugins that work the same way, and we have a real hassle.

So first off, I tucked all the files, except for the one modified wp-config.php, into a folder in a safe place. Next, I greatly streamlined the install process. At a minimum, the user only need edit a single configuration file, autoconfig.php. If desired, the various blogs can each have individual config files, but it’s no longer necessary.

I’ve added user-accessible functions (and the really handy VUSER constant) that can be used in themes and plugins. I’ve added the ability to customize the location of the configuration files, so the security-conscious can move them entirely out of the Web directories if they wish. Overall, we are left with a easy but powerful system for running virtually any number of blogs off a single install of WordPress.

Install instructions are included with the download. Still have questions? Check out the readme and the FAQ. (Note: Sometimes the readme will list a higher version than the download. That happens if I have a development version installed.)


Here’s what you’re really looking for: the download link.

For the truly latest and greatest, I suggest you go get it from GitHub.

Here is a local link, which probably has an older (but possibly more stable) version:
Virtual Multiblog v2.6.2

History/ Acknowledgements

For a detailed history, please see the readme file in the download.

Many of the improvements to version 2 were based upon or inspired by commenters to my blog. To them, and to everyone who has sent comments, I am grateful.

Good luck. Have fun.

752 Responses to Virtual Multiblog for WordPress

  1. Wayne says:

    My main concerns was that I setup VMB similar to the advice in this post as I wanted to plan ahead for when I add language support to my site.

    My concern is now upgrading to the latest core of WP without breaking my custom theme. Any resources you would recommend to test before upgrading?

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