Conflicting ruby versions - ruby-on-rails

Question

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.

Answer 1

Ran into this same issue and thought I'ld share my findings. There was a 1.8.7 ruby version installed by an rpm (centos 6.3), and I compiled 1.9.3 from sources and put it in a directory /opt/upnxt/ruby. I changed my environment to:
export PATH=/opt/upnxt/ruby/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/sbin
export LD_LIBRARY_PATH=/opt/upnxt/ruby/lib64
export RUBYPATH=/opt/upnxt/ruby/bin
export RUBY_HOME=/opt/upnxt/ruby
export RUBYLIB=/opt/upnxt/ruby/lib64/ruby/1.9.1:/opt/upnxt/ruby/lib64/ruby/1.9.1/x86_64-linux
export GEM_HOME=/opt/upnxt/ruby/lib64/ruby/1.9.1
export GEM_PATH=/opt/upnxt/ruby/lib64/ruby/1.9.1:/opt/upnxt/ruby/lib64/ruby/gems/1.9.1
and then when running:
$ ruby /opt/upnxt/ruby/bin/gem environment
RubyGems Environment:
- RUBYGEMS VERSION: 1.8.23
- RUBY VERSION: 1.9.3 (2012-11-10 patchlevel 327) [x86_64-linux]
- INSTALLATION DIRECTORY: /opt/upnxt/ruby/lib64/ruby/1.9.1
- RUBY EXECUTABLE: /usr/bin/ruby
- EXECUTABLE DIRECTORY: /opt/upnxt/ruby/lib64/ruby/1.9.1/bin
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-linux
- GEM PATHS:
- /opt/upnxt/ruby/lib64/ruby/1.9.1
- /opt/upnxt/ruby/lib64/ruby/gems/1.9.1
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :benchmark => false
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- http://rubygems.org/
When running without the 'ruby' command in front, I would get:
$ /opt/upnxt/ruby/bin/gem environment
/opt/upnxt/ruby/lib64/ruby/1.9.1/x86_64-linux/rbconfig.rb:7: ruby lib version (1.9.3) doesn't match executable version (1.8.7) (RuntimeError)
from /opt/upnxt/ruby/lib64/ruby/1.9.1/rubygems.rb:31:in `require'
from /opt/upnxt/ruby/lib64/ruby/1.9.1/rubygems.rb:31
from /opt/upnxt/ruby/bin/gem:8:in `require'
from /opt/upnxt/ruby/bin/gem:8
because of the default #!/usr/bin/ruby as stated earlier. I guess that's why one should use "#!/bin/env ruby" as a shebang instead (or "#!/usr/bin/env ruby")
If someone can tell me how to change the "RUBY EXECUTABLE" from the "gem environment" output so I won't need to specify it on the commandline, I would be grateful
cheers,
Gerrit

Answer 2

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

Answer 3

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.

Answer 4

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