How do I use RVM and create globally available gems?

I'm running Mac OSX 10.6.4 and have installed RVM. Its been great so far, I really love the way it lets me manage having multiple versions of rails and ruby on the same machine without headaches!

However, I don't want to have to install certain gems (such as passenger) for each setup. Is there a way to share gems between gemsets? I have a [email protected] and 1.9.2@rails3, can I have gems such as passenger, mysql, and capistrano installed once and used with all versions?

There is something called the global gemset, and it is shared between all your gemsets of a certain ruby-version. But you can't share gems between ruby-versions.

However, what you can do is create a list of gems that will be installed automatically when adding a new ruby version. That is described here. In short: edit a file called ~/.rvm/gemsets/global.gems to contain the list of gems you want to be there for each ruby-version.

Hope it helps.

With the latest RVM version (1.17.0 and newer) just type:

rvm @global do gem install passenger

or

rvm 1.9.3@global do gem install passenger if you need it only for a specific version of ruby.