Interactive Ruby Shell

Interactive Ruby Shell
	Screenshot The screenshot session as same as the article example
Developer(s)	Keiju Ishitsuka
Stable release	0.9.6 / June 30, 2009
Repository	github.com/ruby/irb ;
Written in	Ruby
Operating system	Cross-platform
Platform	Ruby interpreter
Type	Ruby shell
License	Ruby License; BSD License
Website	www.ruby-lang.org/en/

Interactive Ruby Shell (IRB or irb) is a REPL for programming in the object-oriented scripting language Ruby. The abbreviation irb comes from the fact that the filename extension for Ruby is ".rb", although interactive Ruby files do not have an extension of ".irb". The program is launched from a command line and allows the execution of Ruby commands with immediate response, experimenting in real-time. It features command history, line editing capabilities, and job control, and is able to communicate directly as a shell script over the Internet and interact with a live server. It was developed by Keiju Ishitsuka. Program usage:

irb [ options ] [ programfile ] [ argument... ]

Example usage:

irb(main):001:0> n = 5
=> 5
irb(main):002:0> def fact(n)
irb(main):003:1>   if n <= 1
irb(main):004:2>     1
irb(main):005:2>   else
irb(main):006:2*     n * fact(n - 1)
irb(main):007:2>   end
irb(main):008:1> end
=> :fact
irb(main):009:0> fact(n)
=> 120