# phpman > man > irb(1)

> **TLDR:** Interactive Ruby shell.
>
- Start the interactive shell:
  `irb`

*Source: tldr-pages*

---

[IRB(1)](https://www.chedong.com/phpMan.php/man/IRB/1/markdown)                 Ruby Programmer's Reference Guide                [IRB(1)](https://www.chedong.com/phpMan.php/man/IRB/1/markdown)

## NAME
     **irb** — Interactive Ruby Shell

## SYNOPSIS
     **irb** [**--version**] [**-dfUw**] [**-I** _directory_] [**-r** _library_] [**-E** _external_[:_internal_]] [**-W**[_level_]]
         [**--**[no]inspect] [**--**[no]multiline] [**--**[no]singleline] [**--**[no]echo] [**--**[no]colorize]
         [**--**[no]verbose] [**--prompt** _mode_] [**--prompt-mode** _mode_] [**--inf-ruby-mode**] [**--simple-prompt**]
         [**--noprompt**] [**--tracer**] [**--back-trace-limit** _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
     **--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

### -U
                    (Encoding.default_internal) to UTF-8.

### -d

### -f

### -w

### -W

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

### -r

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

     **--noinspect**    Doesn't use inspect for output

     **--multiline**    Uses multiline editor module.

     **--nomultiline**  Doesn't use multiline editor module.

     **--singleline**   Uses singleline editor module.

### --nosingleline
                    Doesn't use singleline editor module.

     **--echo**         Show result(default).

     **--noecho**       Don't show result.

     **--colorize**     Use colorization.

     **--nocolorize**   Don't use colorization.

     **--verbose**      Show details.

     **--noverbose**    Don't show details.

     **--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 --multiline and
                    --singleline.

### --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.

## ENVIRONMENT
     IRBRC

     Also **irb** depends on same variables as [ruby(1)](https://www.chedong.com/phpMan.php/man/ruby/1/markdown).

## 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**
           => :t
           irb(main):005:0> [**t(3)](https://www.chedong.com/phpMan.php/man/t/3/markdown)**
           => 4
           irb(main):006:0> **if** [**t(3)](https://www.chedong.com/phpMan.php/man/t/3/markdown)** **==** **4**
           irb(main):007:1> **p** **:ok**
           irb(main):008:1> **end**
           :ok
           => :ok
           irb(main):009:0> **quit**
           %

## SEE ALSO
     [ruby(1)](https://www.chedong.com/phpMan.php/man/ruby/1/markdown).

## REPORTING BUGS
     ••   Security vulnerabilities should be reported via an email to <_security@ruby-lang.org_>.  Re‐
         ported problems will be published after being fixed.

     ••   Other bugs and feature requests can be reported via the Ruby Issue Tracking System
         (**<https://bugs.ruby-lang.org/>**). Do not report security vulnerabilities via this system be‐
         cause it publishes the vulnerabilities immediately.

## AUTHORS
     Written by Keiju ISHITSUKA.

UNIX                            August 11, 2019                           UNIX