I am having problems with conflicting versions of Ruby that I have installed. I had 1.8.6 and then installed 1.8.7 and it has caused problems. I get the following error when trying to run my ruby on rails app:
/usr/local/lib/ruby/1.8/i686-linux/rbconfig.rb:7: ruby lib version (1.8.6) doesn't match executable version (1.8.7) (RuntimeError)
I would like to remove 1.8.7 somehow and just use 1.8.6 but have no idea how to go about doing this.
Just change your $PATH to point to the version you want.
I install ruby from the tarball (and not from the distribuition package). This way I can have several different versions working at the same time, I have just to update the $PATH in the session that I want to use a different version.
Your easiest path and future proof too would be using rvm. Download the version of ruby you want with rvm and make it the default.
Installation: http://rvm.beginrescueend.com/rvm/install/
Making it default:
rvm 1.8.6 --default
The whole process would take not more than 15 minutes. Everything is clearly explained in this. Your environment will be set before you finish watching this podcast:
http://railscasts.com/episodes/200-rails-3-beta-and-rvm
Yes, setting the path:
export PATH=yourrubypath/bin:$PATH
should do it.
I recommend you install rvm, that way you can run different ruby versions and manage gem sets in a very easy way
The installation instructions are here. However it basically reduces to:
bash < <( curl http://rvm.beginrescueend.com/releases/rvm-install-head )
Then you can install a newer ruby from source (it will compile it!):
$ rvm install 1.9.1 ; rvm 1.9.1
$ ruby -v
ruby 1.9.1p243 (2009-07-16 revision 24175) [x86_64-linux]
$ which ruby
/home/you/.rvm/ruby-1.9.1-p243/bin/ruby
You can go back to the "system" one doing:
$ rvm system