NAME

       irb — Interactive Ruby Shell

SYNOPSIS

       irb  [--version]  [-dfm]  [-I  directory]  [-r  library] [--[no]inspect] [--[no]readline] [--prompt mode]
           [--prompt-mode     mode]     [--inf-ruby-mode]     [--simple-prompt]     [--noprompt]      [--tracer]
           [--back-trace-limit n] [--irb_debug n] [--] [program_file] [argument ...]

DESCRIPTION

       irb is the REPL(read-eval-print loop) environment for Ruby programs.

OPTIONS

       --version      Prints the version of irb.

       -E external[:internal]
       --encoding external[:internal]
                      Same  as  `ruby  -E' .  Specifies the default value(s) for external encodings and internal
                      encoding. Values should be separated with colon (:).

                      You can omit the one for internal encodings, then  the  value  (Encoding.default_internal)
                      will be nil.

       -I path        Same as `ruby -I' .  Specifies $LOAD_PATH directory

       -U             Same    as    `ruby   -U'   .    Sets   the   default   value   for   internal   encodings
                      (Encoding.default_internal) to UTF-8.

       -d             Same as `ruby -d' .  Sets $DEBUG to true.

       -f             Suppresses read of ~/.irbrc.

       -h
       --help         Prints a summary of the options.

       -m             Bc mode (load mathn, fraction or matrix are available)

       -r library     Same as `ruby -r'.  Causes irb to load the library using require.

       --inspect      Uses `inspect' for output (default except for bc mode)

       --noinspect    Doesn't use inspect for output

       --readline     Uses Readline extension module.

       --noreadline   Doesn't use Readline extension module.

       --prompt mode
       --prompt-mode mode
                      Switch prompt mode. Pre-defined prompt modes are  `default',  `simple',  `xmp'  and  `inf-
                      ruby'.

       --inf-ruby-mode
                      Uses prompt appropriate for inf-ruby-mode on emacs.  Suppresses --readline.

       --simple-prompt
                      Makes prompts simple.

       --noprompt     No prompt mode.

       --tracer       Displays trace for each execution of commands.

       --back-trace-limit n
                      Displays backtrace top n and tail n.  The default value is 16.

       --irb_debug n  Sets internal debug level to n (not for popular use)

ENVIRONMENT

       IRBRC

       Also irb depends on same variables as ruby(1).

FILES

       ~/.irbrc        Personal irb initialization.

EXAMPLES

             % irb
             irb(main):001:0> 1 + 1
             2
             irb(main):002:0> def t(x)
             irb(main):003:1> x+1
             irb(main):004:1> end
             => nil
             irb(main):005:0> t(3)
             => 4
             irb(main):006:0> if t(3) == 4
             irb(main):007:1> p :ok
             irb(main):008:1> end
             :ok
             => :ok
             irb(main):009:0> quit
             %

SEE ALSO

       ruby(1).

REPORTING BUGS

       Security  vulnerabilities should be reported via an email to ⟨security@ruby-lang.org⟩.  Reported problems
       will be published after being fixed.

       And you can report other bugs and feature requests via the Ruby Issue Tracking System  (http://bugs.ruby-
       lang.org).    Do   not   report  security  vulnerabilities  via  the  system  because  it  publishes  the
       vulnerabilities immediately.

AUTHORS

       Written by Keiju ISHITSUKA.

UNIX                                            November 15, 2012                                       IRB(1)()