I’ve talked about this before. 100% duplication of content on multiple sites is bad. So why am I going to tell you how to do it? And better, why am I going to tell you how to do it without Multisite? Because as a proof-of-concept, it was interesting.
The rest of this post tells you how to do something I don’t advocate, nor will I support. If you have a better way, or improvements, please leave comments. Otherwise, you’re on your own when you do this. I will not help you do it in any way, shape, or form.
Honestly, I still think this is a pretty silly idea. Duplicating content is a terrible user experience, and I still flat-out decline to accept any work for doing this. Sharing content is one thing, but 100% duplication of sites makes no sense at all to me. Yoast also says it’s a bad idea. But, if you really are totally 100% dedicated to do this, and you absolutely are going to, damn the torpedos, then you should do this in the least computationally expensive way possible. And that would be a single install.
Now all that said, this means you’ll need to do a lot of monkey-work, so why do I call this ‘easier’? In many ways, easy is relative and this will be hard, complicated, and may I stress, entirely unnecessary. You’re going the hard way around for something that good planning and a solid understanding of the Internet totally negates. Remember the absolute rule of the Internet: Use one URL per page and never change that URL. 1
The way to make all this work, without Multisite, is by tricking your domain a little. There’s a neat trick with parking (or mirroring, depends on your host) domains, that lets you keep the other domain URL in your browser’s address bar. That’s what I do with this site, actually, halfelf.org is parked on top ipstenu.org. And with a park, the URL always stays as halfelf.org. Hey look! Two URLs, one site! Multisite has secret sauce to know “Someone’s coming to HalfElf, send ’em to site #2.” But on a single site, all my links would still be ipstenu.org and not halfelf.org.
Now how do you use this to duplicate content? You use relative URLs.
So here’s a real example. I have twofer.elftest.net set up to mirror plugins.elftest.net (which will give you a coming soon page, it’s just where I like to blow things up for tests).
In the beginning of this post, when I linked to my old post about Duplication Dilution, the URL was
http://halfelf.org/2012/duplication-dillution/ and that is what we call an absolute URL. Because I’m mapping domains, I can leave those in without worry, but if I wasn’t, I’d change that URL to
/2012/duplication-dillution/ instead. Right away this makes my URLs entirely relative, no domain name included, and I’m off to the races.
This doesn’t solve everything, though. See, WordPress really wants to use absolute URLs. There are plugins like root relative URLs, and those will help a lot. None of them back-ports your existing posts, though, so for that it’s nothing for it but to search/replace the DB and change your post content. 2 I really like those plugins because now for a new post, when I add a link and chose to link to existing content, it happily works:
And when I add an image, it too smartly handles as I want it to:
That’s the easy part of all this, though. Now you have to disable canonical URLs, so that you don’t end up with even more of the dread duplicate content penalty in WordPress.
This also stops WP from redirecting things like
http://plugins.elftest.net/?p=1 as well, however, so keep that in mind. Of course, that’s what you wanted. But they don’t address the problem of your source code. If I view source on
twofer.elftest.net, it still showed
plugins.elftest.net, and that would be a problem for images and themes. You’ll need to toss in this to your wp-config.php, which will dynamically change your URL to be whatever URL I’m visiting from, so that changes automatically. Awesome.
define('WP_HOME', 'http://' . $_SERVER['HTTP_HOST']); define('WP_SITEURL', 'http://' . $_SERVER['HTTP_HOST']); define('DOMAIN_CURRENT_SITE', $_SERVER['HTTP_HOST']);
Now I want to tell WordPress that wp-content is not in URL/wp-content/ so let’s just put this in and make it relative too!
I’m still going to have to search and replace my old post content (I used Velvet Blues for this):
But that didn’t address the problem of the source code. 90% of WP now thinks it’s all on twofer, which is what I wanted, but look at XMLRPC:
And even better, when I try to log in via twofer, it still says I’m going to plugins. Oh and it doesn’t pass through cookies, so really, I never log in to Twofer. Realistically? This isn’t a problem. I’m always going to use plugins.elftest for all this when I log in on the backend, and since the convenience of all this was meant for the front end, and it’s just pingbacks. And why is that? Honestly, I don’t know. I have a guess that since, at WordPress’ heart, the site is always plugins, the absolute URL there has to be what it is, but in so far as all that goes, I think it meets the needs of why most people want to do this.
Conclusions? You can do this. If you wanted to, you can hardcode the theme so the domain you visit the site with will dynamically change the header image, or widgets, or anything else you want. PHP is pretty cool that way and WordPress is too. But I would never do it, except as an experiment to see what I could do it at all.