Installing Wordpress μ—the multi-user version of Wordpress—is quite different from the single-user version. Most people have trouble preparing their localhost server to meet the requirements of having mod_rewrite enabled for the Apache or other Web server. Even if they manage to enable rewrite module for the server, they still get an error message saying:
Warning!Installing to http://localhost/ is not supported. Please use http://localhost.localdomain/ instead.
Here's simple step-by-step instruction to successfully install Wordpress Mu on your localhost server. For my convenience, I am assuming that you have Apache and know how to install Wordpress locally.
Download Wordpress Mu and unzip it. Rename the folder to say, wpmu. Now, transfer the folder to the WWW directory of the local server. (You can also leave the folder at any desired location and create an alias pointing to the folder.)
Read the READ ME file in Wordpress Mu folder. It will help you in completing the installation successfully.
Enable mod_rewrite by editing the httpd.conf. It can be done by accessing file in the Apache folder. Httpd.conf file will be in different locations depending on your server installation. For example, in a XAMPP server installation, it will be in C:\xampplite\apache\conf, or something similar. If you have Webmin installed, go to Webmin panel-> Webserver-> Global Configuration -> Configure Apache modules, and check the rewrite option and save.
If you don't have Webmin installed, look for this in httpd.config file.
#LoadModule rewrite_module modules/mod_rewrite.so
Remove the # at the beginning of the line to activate the rewrite module. It should look like:
LoadModule rewrite_module modules/mod_rewrite.so
Set AllowOverride directive for directory in httpd.config to All. If the AllowOverride directive is set to None in your Apache httpd.config file, then .htaccess files are ignored. Look for the following in the config file and make the change.
You might have to change AllowOverride option to All for your DocumentRoot directory. Look for it and change to All. Restart the server.
Now, if you try to load the Wordpress Mu folder by visiting http://localhost/wpmu (or http://localhost/YourWordpressMufolder), it will give the error: Installing to http://localhost/ is not supported. Please use http://localhost.localdomain/ instead. What's this? It actually means that it needs a domain in the address, like the address of websites on the Web. Wordpress Mu is asking for an address such as name.domain or wp.mu. For instance, Google.com has a name (google) and a domain (com). How to fix this?
We need to edit our hosts file so that a name.domain address redirects to http://localhost. If you are using Windows, it should be found in c:\windows\system32\drivers\etc. In case you are using Ubuntu, it will be found in the etc folder in Ubuntu File System. To edit this file in Ubuntu, open Terminal, and run the following command:
sudo gedit /etc/hosts
Insert the following line in the hosts file:
Save and close. You can replace wp.mu with anything.anything. Now http://wp.mu is just another address for http://localhost. [http://wp.mu is a domain in the real world. If you choose to use wp.mu for your Wordpress Mu installation, you won't be able to access this site from your computer.]
All set. Now you can load http://wp.mu/wpmu and install Wordpress Mu following on-screen instructions. However, it will not work with subdomain option for users' blogs. That hasn't been activated yet. Read about it at Ma.tt, the Wordpress developer's blog.