gem install rails ERROR: While executing gem ... (Errno::EACCES) - ruby-on-rails

Question

I somehow messed my $PATH up. (changed it) and my ruby and rails gems weren't working. What I did in efforts to fix this was to reinstall RVM. Now my ruby works fine in the Terminal.
On running gem install railsI get greeted with this:
Permission denied - /Users/emKaro/.rvm/gems/ruby-2.0.0-p247/gems/atomic-1.1.13/test/test_atomic.rb
When I try to install rails through sudo gem install rails, I get this error:
ERROR: While executing gem ... (Errno::EACCES)
I have XCode installed with Command-Line tools installed as well. Even went ahead to install GCC but get the very same error when I try to install rails.
This is the full error message
ERROR: While executing gem ... (Errno::EACCES)
Permission denied - /Users/emKaro/.rvm/gems/ruby-2.0.0-p247/gems/atomic-1.1.13/test/test_atomic.rb
emmanuels-imac:~ siaW$ sudo gem install rails
Password:
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
--with-atomic_reference-dir
--without-atomic_reference-dir
--with-atomic_reference-include
--without-atomic_reference-include=${atomic_reference-dir}/include
--with-atomic_reference-lib
--without-atomic_reference-lib=${atomic_reference-dir}/
/Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:519:in `try_link0'
from /Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:817:in `try_run'
from extconf.rb:24:in `<main>'
Gem files will remain installed in /Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.13 for inspection.
Results logged to /Users/emKaro/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.13/ext/gem_make.out
I am the admin of my computer and running Mac OS 10.8.3. I'd appreciate some help with the rails install.
EDIT:
Thanks #Christoph
The only code that helped was to actually remove the RVM folder with
sudo rm -rf ~/.rvm/
I tried only to uninstal and it didn't work. So removing the folder and then reinstalling RVM does the job.

Answer 1

Like Dave pointed out up there, there should be no need to sudo any Gem installation. You could try to reset the permissions on your RVM directory:
sudo chown -R emKaro: ~/.rvm/
and try your Gem instllation again. If that doesn't work out, you should consider removing your RVM installation and start over:
sudo rm -rf ~/.rvm/ # remove your RVM directory
There should really be no need for using sudo in any of this.

Answer 2

I'm running 10.8.5 OSX and was trying to install Rails with Ruby 1.9.3-p448 - so I don't know if it's exactly the same problem, but by looking in the mkmf.rb code where it failed, I found that the problem was that the basic CC command wasn't running. For some reason, it needed to search for the folders in /usr/local, and for some reason, /usr/local was set to 740 permissions on my install (which I had gotten from someone else so not sure what he had done prior to my getting the machine.)
So after I did chmod +x /usr/local, everything worked ok.

Answer 3

I had this problem in Ubuntu, but it was because I didn't installed the rvm with "Run command as a login shell", after the installation of rvm they told about this, and the link to look for the information to enable in ubuntu.
Here's the link:
https://rvm.io/integration/gnome-terminal
For RVM to work properly, you have to check the 'Run command as login shell' checkbox on the Title and Command tab of gnome-terminal's Edit ▸ Profile Preferences menu dialog, in case the menu is missing right click the terminal app and navigate Profiles ▸ Profile Preferences.