Tips: Update your rubygems (with special case)

The most suggested updating technique is

$ sudo gem update --system

But this technique may not work with rubygems version 1.1 and 1.2. run

$gem -v

to know your rubygems version.

For those having these two versions, install rubygems-update gem and then run update_rubygems command (as sudo if necessary)

$ sudo gem install rubygems-update
$ sudo update_rubygems

View offline documentation of installed ruby gems

From command line, just run this -

$ gem server

This will start ruby documentation server on port 8088

previously it was

$ gem_server

which is now deprecated and may not work in your system