Do you like tab completion with bash? Now you can have it with irb too! Just setup your .bashrc file with an alias so you don’t have to remember the entire command line. It’s not exactly the same as bash. You will have to hit the tab key twice. On my Ubuntu 8.10 system it works as listed below.

irb --readline -r irb/completion

To edit .bashrc:

vi ~/.bashrc

add the following alias

alias irb='irb --readline -r irb/completion'

You can also make the following changes to your ~/.irbrc file instead of an alias.

require 'irb/completion'
IRB.conf[:USE_READLINE] = true