Provided by: ruby2.5_2.5.5-4ubuntu2_amd64 bug


     ri — Ruby API reference front end


     ri [-ahilTv] [-d DIRNAME] [-f FORMAT] [-w WIDTH] [--[no-]pager] [--server[=PORT]]
        [--[no-]list-doc-dirs] [--no-standard-docs] [--[no-]{system|site|gems|home}]
        [--[no-]profile] [--dump=CACHE] [name ...]


     ri is a command-line front end for the Ruby API reference.  You can search and read the API
     reference for classes and methods with ri.

     ri is a part of Ruby.

     name can be:

           Class | Module | Module::Class

           Class::method | Class#method | Class.method | method

           gem_name: | gem_name:README | gem_name:History

     All class names may be abbreviated to their minimum unambiguous form.  If a name is
     ambiguous, all valid options will be listed.

     A ‘.’ matches either class or instance methods, while #method matches only instance and
     ::method matches only class methods.

     README and other files may be displayed by prefixing them with the gem name they're
     contained in.  If the gem name is followed by a ‘:’ all files in the gem will be shown.  The
     file name extension may be omitted where it is unambiguous.

     For example:

           ri Fil
           ri File
           ri zip
           ri rdoc:README

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

           ri 'Array.[]'
           ri compact\!

     To see the default directories ri will search, run:

           ri --list-doc-dirs

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

     ri options may be set in the RI environment variable.

     The ri pager can be set with the RI_PAGER environment variable or the PAGER environment


                    In interactive mode you can repeatedly look up methods with autocomplete.

     --[no-]all     Show all documentation for a class or module.

     --[no-]list    List classes ri knows about.

     --[no-]pager   Send output to a pager, rather than directly to stdout.

     -T             Synonym for --no-pager.

     -w WIDTH
     --width=WIDTH  Set the width of the output.

                    Run RDoc server on the given port.  The default port is 8214.

     -f FORMAT
                    Use the selected formatter.  The default formatter is bs for paged output and
                    ansi otherwise.  Valid formatters are: ansi, bs, markdown, rdoc.

     --help         Show help and exit.

     --version      Output version information and exit.

     Data source options:

                    List the directories from which ri will source documentation on stdout and

     -d DIRNAME
                    List of directories from which to source documentation in addition to the
                    standard directories.  May be repeated.

                    Do not include documentation from the Ruby standard library, site_lib,
                    installed gems, or ~/.rdoc.  Use with --doc-dir.

     --[no-]system  Include documentation from Ruby's standard library.  Defaults to true.

     --[no-]site    Include documentation from libraries installed in site_lib.  Defaults to

     --[no-]gems    Include documentation from RubyGems.  Defaults to true.

     --[no-]home    Include documentation stored in ~/.rdoc.  Defaults to true.

     Debug options:

                    Run with the Ruby profiler.

     --dump=CACHE   Dump data from an ri cache or data file.


     RI           Options to prepend to those specified on the command-line.

     PAGER        Pager program to use for displaying.

     HOMEPATH     Path to the user's home directory.


     ~/.rdoc      Path for ri data in the user's home directory.


     ruby(1), rdoc(1), gem(1)


     ·   Security vulnerabilities should be reported via an email to
         Reported problems will be published after being fixed.

     ·   Other bugs and feature requests can be reported via the Ruby Issue Tracking System
         (  Do not report security vulnerabilities via this system
         because it publishes the vulnerabilities immediately.


     Written by Dave Thomas <>.