Ruby & Rails installation on a Mac

I used railstutorial.org to install the latest version of ruby and the latest version of rails on my machine.

at the end of the ins开发者_如何学JAVAtallation I checked

ruby -v ==> 1.9.2 (great)
rails -v ==> 3.0.1 (great)

this morning I opened up terminal

ruby -v
ruby 1.8.6 (2009-06-08 patchlevel 369) [universal-darwin9.0]
rails -v
Rails 1.2.6

what happened?

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My advice for people who are installing ruby is to use RVM. It makes managing your ruby versions and gem versions really simple and you can install multiple ruby versions side by side.

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You might want to read this post: http://rubylearning.com/blog/2010/12/20/how-do-i-keep-multiple-ruby-projects-separate/

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You can use Cinderalla to the whole ruby/rvm/mysql/redis/git/... stack set up properly. Cinderella installs everything in ~/Developer and fixes up your PATH as well. I had some issues with a corrupt git mirror last time I used Cinderalla though so YMMV.

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With many unix variants, you are likely to have multiple versions of Ruby--particularly if you installed Ruby 1.9 and the system already had 1.8 installed. Essentially, the 1.8 version of Ruby has a higher precedence in your PATH than the 1.9 version. The Ruby Gems command keeps the libraries separate between 1.8 and 1.9 so that the platform will be reasonably stable.

To correct the problem, you have to find where ruby 1.9 is installed. Once you do that, you'll need to override your PATH variable. Assuming 1.9 is installed in the path: /opt/ruby-1.9.2, you will need to set your PATH like this:

PATH=/opt/ruby-1.9.2/bin:$PATH
export PATH

To make the path respect what you want every time, add that to your ~/.profile file (create it if necessary). Once the path has been set, it sould be able to find the correct version of Rails again.

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I cannot say for certain because I cannot debug you OSX machine from here, however, I had a very similar occurrence. The problem was caused because I had installed ruby and then rails on my machine using sudo or from the root account. Then when I discovered rvm I installed everything in my user account. When I logged off and back in I appeared to lose everything. I was pulling out my hair. I was pissed that I was going to have to reinstall everything again... when I found the magic.

from the command line execute the command:

rvm list

you'll see that your new version of ruby is there. you'll also notice the tokens that indicate that it is just a normal version. It is not current or default. (see it yet)

Now if you run the command:

rvm use 1.9.2 --default

then every time you login/off and restart your machine your user account will default to that version of ruby and all of the gems that you installed against that version.