ri
TLDR
View class documentation
$ ri [Array]
View method documentation$ ri [Array#map]
View instance method$ ri [String#split]
View class method$ ri [File.open]
List all classes$ ri -l
SYNOPSIS
ri [options] [name...]
DESCRIPTION
ri (Ruby Information) displays Ruby documentation from the command line. It reads documentation generated by RDoc and provides quick access to class and method information.
PARAMETERS
-l, --list
List classes.-f, --format name
Output format.-i, --interactive
Interactive mode.-T, --no-pager
Don't use pager.--doc-dir dir
Documentation directory.
EXAMPLES
$ # Class documentation
ri Array
ri String
# Instance method (use #)
ri Array#each
ri String#gsub
# Class method (use .)
ri File.read
ri Dir.glob
# Search for method
ri -l | grep map
# Interactive mode
ri -i
ri Array
ri String
# Instance method (use #)
ri Array#each
ri String#gsub
# Class method (use .)
ri File.read
ri Dir.glob
# Search for method
ri -l | grep map
# Interactive mode
ri -i
NOTATION
$ Class - ri Array
Class#method - Instance method (ri Array#map)
Class.method - Class method (ri File.open)
Class::Const - Constant (ri File::SEPARATOR)
Class#method - Instance method (ri Array#map)
Class.method - Class method (ri File.open)
Class::Const - Constant (ri File::SEPARATOR)
CAVEATS
Documentation must be installed. Use gem rdoc --all to generate gem docs. Part of Ruby standard library.
HISTORY
ri is part of Ruby's RDoc system, providing command-line documentation access since early Ruby versions.
