Ruby Quicktips

Console tip: retrieve the last return value with underscore

In IRB you can retrieve the last return value from a command by using the underscore _ sign:

$ irb
>> 2*3
=> 6
>> _ + 7
=> 13
>> _
=> 13

This also works in the Rails console:

$ script/console
>> User.first
=> #<User id: 7, first_name ...
>> user = _
=> #<User id: 7, first_name ...
>> user
=> #<User id: 7, first_name ...

This is quite useful, when you forgot to assign the return value of an expression to a variable.