get help on what commands are available (some output truncated). : RubyGems Language Basics Ruby

$ gem help commands

GEM commands are:

 build         Build a gem from a gemspec
 ...
 specification Display gem specification (in yaml)
 uninstall     Uninstall a gem from the local repository
 unpack        Unpack an installed gem to the current directory
 update        Update the named gem (or all installed gems) in the local repository

For help on a particular command, use 'gem help COMMAND'.

Commands may be abbreviated, so long as they are unambiguous.
e.g. 'gem i rake' is short for 'gem install rake'.