ri: Ruby Interactive Reference

ri an online reference tool developed by Dave Thomas, the famous pragmatic programmer.

When you have a question about the behavior of a certain method, you can invoke ri to read the brief explanation of the method.

You can get ri from ri: Ruby Interactive

Usage Syntax

Here is simple syntax to use ri

ri [ options ] [ methodname... ]

Here is a complete list of options −

Sr.No. Command & Description



Displays version and exits.


--line-length = n

-l n

Sets the line length for the output (minimum is 30 characters).




Displays just a synopsis.


--format = name

-f name

Uses the name module (default is Plain) for output formatting. Here are the available modules −

  • Tagged − Simple tagged output
  • Plain − Default plain output

name should be specified in any of the following forms −

  • Class
  • Class::method
  • Class#method
  • Class.method
  • method.