rbenv is the best solution to to pick a ruby version for your specific environment.
However, even if rbenv has been installed successfully, the “Terminal” in Aptana Studio cannot stop choose the system default ruby version.
Because aptana terminal does not load ~/.bash_profile
Fix
My Environments
- Mac OS X Mountain Lion
- Aptana Studio 3
- rbenv 0.4.0
Aptana terminal load the .aptanarc instead of .bashrc when start up. You can insert a path configurations for rbenv on it like this
$ echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.aptanarc $ echo 'eval "$(rbenv init -)"' >> ~/.aptanarc
Enjoy, rubymongers!
ashphy coding 
Do you know what happens if using ZSH? Given that the shell is bash.
I found an article, but it doesn’t work on my aptana.
The simplest way is to put $ /bin/zsh on your terminal.