Download and compile eRuby

1. Download and unzip http://www.modruby.net/en/index.rbx/eruby/download.html
2. Go to the unzipped directory in terminal
3. type ./configure.rb
4. type make
5. type make install
6. Copy the generated eruby file to your local cgi-bin

Modify your httpd.conf settings

1. add this line to add the rhtml support:

   AddType application/x-httpd-eruby .rhtml
   Action application/x-httpd-eruby /cgi-bin/eruby

2. And modify this line so your server will look for index.rhtml pages in directories:
   DirectoryIndex index.html index.shtml index.rhtml

Running straight .rb files outside your cgi-bin folder (optional)

You can run any scripts from your cgi-bin if you properly add the #!(she bang) location to your ruby intepreter at the top of your scripts, but you can also make these scrips run outside of your cgi-bin by just adding this line to your httpd.config, just add the .rb extension to the filename:

AddHandler cgi-script .rb

I was doing this for awhile so I could execute scripts through the web but the RHTML method is better. Still, there could be applicable reasons for a person to want to do this. Just keep in mind, that when accessing Ruby scripts directly from a webpage you must at least specify a content-type (puts: “content-type: text/plain\n”) in your header or use the convenient cgi class from the Ruby standard library that does that (and a whole lot more) for you.

Improving Performance (optional)

The above is a really quick way to add Ruby support to your local webserver however, there’s one downside – it has to start up the Ruby interpreter everytime you hit an rhtml file with your browser. If you want something a little more dedicated look into the mod_ruby apache module which embeds a Ruby interpreter into Apache’s (inside your web server’s memory), to let Ruby CGI scripts execute natively, so scripts start up and run far faster. This is the equivalent as mod_php for PHP, that’s built into your MAMP setup.

Additionally, as a speed boost, you could use fast cgi to keep the eRuby interpreter instantiated, if for some reason you can’t use mod_ruby.

Helpful links:

http://www.rubycentral.com/book/web.html