irb --- Interactive Ruby Shell


     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 ...]


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


     --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.

     --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

     --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'.

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

                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

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



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


     ~/.irbrc        Personal irb initialization.


       % irb
       irb(main):001:0> 1 + 1
       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
       irb(main):009:0> quit




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

     And you can report other bugs and feature requests via the Ruby Issue
     Tracking System (  Do not report security
     vulnerabilities via the system because it publishes the vulnerabilities


     Written by Keiju ISHITSUKA.


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