Ruby Information

Use the ri command to access Ruby documentation which is installed locally on your system.

Instructions

Use ri [options] <whatever> to look up information about Ruby classes, modules, and methods.

• Combine with head to fast check documentation before displaying full content.
• Combine with wc to count relevant items when searching for multiple entries.
• Combine with grep to filter results based on keywords.

Consider to add quote to queries with special characters to avoid shell interpretation issues. e.g. ri 'String#blank?'

Scenarios

Direct Lookup

Check specific Ruby classes or methods accurately.

ri Array#push

Search method

Check for methods is implemetned in a class or module and get a count of results.

ri '.find' | wc -l

Use grep to filter results.

ri '.find' | grep 'Enumerable'

Note: Use wc and grep to ensure the output is concise and relevant.

List Names

Get a list of all classes and modules under a specific namespace.

ri --list 'MyModule::Application'

Preview Documentation

Preview the first few lines of documentation for a method or class.

ri 'String#upcase' | head -n 10

Explore Options

Explore various options available with the ri command.

ri --help

Documentation

You can get README and other documentation if bundled with gems.

ri rspec:README.md

To list all available documentation files for a gem:

ri rspec:

Append the : after the gem name to see all documentation files associated with that gem.

Building Documentation

You can use rdoc to generate and view documentation for your own Ruby projects.

rdoc --format=ri --output=ri_doc .

View the generated documentation using ri:

ri -d ./ri_doc 'MyClass'

References

For more information, refer to the official Ruby documentation: https://ruby.github.io/rdoc/index.html