ri is a documentation viewer for Ruby.

Command line interface to ri

Output of ri --help:

ri v1.0.1 - 20041108


  ri [options]  [names...]

Display information on Ruby classes, modules, and methods.
Give the names of classes or methods to see their documentation.
Partial names may be given: if the names match more than
one entity, a list will be shown, otherwise details on
that entity will be displayed.

Nested classes and modules can be specified using the normal
Name::Name notation, and instance methods can be distinguished
from class methods using "." (or "#") instead of "::".

For example:

    ri  File
    ri  File.new
    ri  F.n
    ri  zip

Note that shell quoting may be required for method names
containing punctuation:

    ri 'Array.[]'
    ri compact\!

By default ri searches for documentation in the following


Specifying the --system, --site, --home, --gems or --doc-dir
options will limit ri to searching only the specified


     --help, -h   you're looking at it

  --classes, -c   Display the names of classes and modules we
                  know about

  --doc-dir, -d <dirname>
                  A directory to search for documentation. If not
                  specified, we search the standard rdoc/ri directories.
                  May be repeated.

       --system   Include documentation from Ruby's standard library:

         --site   Include documentation from libraries installed in site_lib:

         --home   Include documentation stored in ~/.rdoc:

         --gems   Include documentation from Rubygems:

   --format, -f <name>
                  Format to use when displaying output:
                     ansi, bs, html, plain, simple
                  Use 'bs' (backspace) with most pager programs.
                  To use ANSI, either also use the -T option, or
                  tell your pager to allow control characters
                  (for example using the -R option to less)

--list-names, -l  List all the names known to RDoc, one per line

 --no-pager, -T   Send output directly to stdout.

    --width, -w output width
                  Set the width of the output

  --version, -v   Display the version of ri

Options may also be passed in the 'RI' environment variable

See also