Android - Can I install Ruby and Ruby on Rails on an Android?

this can be done

  1. Compile Ruby and Nodejs for android
  2. Install on device and configure with c/c++ ide (You can use C4droid,CCTools,Terminal IDE.... for installing the expansion modules on с/с++)
  3. Install rails ($gem install rails)

Screenshot 1 Screenshot 2 Screenshot 2 (Click image to enlarge)

The Android Scripting Environment said to plan on Ruby. Might be worth a check how far they got; at least they're tagged "JRuby" at Google Code. According to their project page:

Scripts can be run interactively in a terminal, in the background, or via Locale. Python, Perl, JRuby, Lua, BeanShell, JavaScript, Tcl, and shell are currently supported, and we're planning to add more.

But be also aware of:

SL4A is designed for developers and is alpha quality software.

An interesting article on this topic which you might want to read is Hacking Android during the holidays. It describes an (successful) attempt to setup and use SL4A to be used with a.o. Ruby.

As for ruby, you may try Termux.

With batteries included. Can you imagine a more powerful yet elegant pocket calculator than a readline-powered python console? Up-to-date versions of perl, python, ruby and node.js are all available.