I am currently using ubuntu 11.10. I just now installed rvm and ruby 1.9.2. When I try to install rails I get the following error
ERROR:  Loading command: install (LoadError)
    no such file to load -- zlib
ERROR:  While executing gem ... (NameError)
    uninitialized constant Gem::Commands::InstallCommand
I tried installing zlib library in many ways but I still get this error and couldn't proceed further.