Adam Sanderson's open_gem

The latest version of rubygems (1.3.2) now has an interface to add commands. Making great use of this feature, Adam Sanderson has written open_gem, a simple but amazingly useful tool.

You use it like this:

$ gem open activerecord

This opens the activerecord gem in your favourite editor (taken from either $GEM_OPEN_EDITOR or $EDITOR environment variables). If there are multiple versions of the gem installed, it will show a menu, letting you choose which version you require.

$ gem open activerecord
Open which gem?
 1. activerecord 2.1.0
 2. activerecord 2.3.2

open_gem itself is a gem, and can be installed with:

$ gem install open_gem

To get it working, you need to have $EDITOR set to something sensible:

$ export EDITOR=mate

If you’re running on OS X and use TextMate, you may have already set $EDITOR to mate -w, which let’s you use TextMate as the editor for git commit messages and much more. However, the -w flag doesn’t work with open_gem, so set the $GEM_OPEN_EDITOR variable, and open_gem will use that instead:

$ export GEM_OPEN_EDITOR=mate

You should now be good to go. If you want to see how it works, just use it on itself!

$ gem open open_gem