Provided by: ruby1.9.1_1.9.3.0-1ubuntu1_amd64 bug


     ruby — Interpreted object-oriented scripting language


     ruby [--copyright] [--version] [-SUacdlnpswvy] [-0[octal]] [-C directory]
          [-E external[:internal]] [-F pattern] [-I directory] [-K c] [-T[level]] [-W[level]]
          [-e command] [-i[extension]] [-r library] [-x[directory]] [-{enable|disable}-FEATURE]
          [--dump=target] [--verbose] [--] [program_file] [argument ...]


     Ruby is an interpreted scripting language for quick and easy object-oriented programming.
     It has many features to process text files and to do system management tasks (as in Perl).
     It is simple, straight-forward, and extensible.

     If you want a language for easy object-oriented programming, or you don't like the Perl
     ugliness, or you do like the concept of LISP, but don't like too many parentheses, Ruby
     might be your language of choice.


     Ruby's features are as follows:

             Ruby is an interpreted language, so you don't have to recompile programs written in
             Ruby to execute them.

     Variables have no type (dynamic typing)
             Variables in Ruby can contain data of any type.  You don't have to worry about
             variable typing.  Consequently, it has a weaker compile time check.

     No declaration needed
             You can use variables in your Ruby programs without any declarations.  Variable
             names denote their scope - global, class, instance, or local.

     Simple syntax
             Ruby has a simple syntax influenced slightly from Eiffel.

     No user-level memory management
             Ruby has automatic memory management.  Objects no longer referenced from anywhere
             are automatically collected by the garbage collector built into the interpreter.

     Everything is an object
             Ruby is a purely object-oriented language, and was so since its creation.  Even such
             basic data as integers are seen as objects.

     Class, inheritance, and methods
             Being an object-oriented language, Ruby naturally has basic features like classes,
             inheritance, and methods.

     Singleton methods
             Ruby has the ability to define methods for certain objects.  For example, you can
             define a press-button action for certain widget by defining a singleton method for
             the button.  Or, you can make up your own prototype based object system using
             singleton methods, if you want to.

     Mix-in by modules
             Ruby intentionally does not have the multiple inheritance as it is a source of
             confusion.  Instead, Ruby has the ability to share implementations across the
             inheritance tree.  This is often called a ‘Mix-in’.

             Ruby has iterators for loop abstraction.

             In Ruby, you can objectify the procedure.

     Text processing and regular expressions
             Ruby has a bunch of text processing features like in Perl.

     M17N, character set independent
             Ruby supports multilingualized programming. Easy to process texts written in many
             different natural languages and encoded in many different character encodings,
             without dependence on Unicode.

             With built-in bignums, you can for example calculate factorial(400).

     Reflection and domain specific languages
             Class is also an instance of the Class class. Definition of classes and methods is
             an expression just as 1+1 is. So your programs can even write and modify programs.
             Thus you can write your application in your own programming language on top of Ruby.

     Exception handling
             As in Java(tm).

     Direct access to the OS
             Ruby can use most UNIX system calls, often used in system programming.

     Dynamic loading
             On most UNIX systems, you can load object files into the Ruby interpreter on-the-

     Rich libraries
             Libraries called "builtin libraries" and "standard libraries" are bundled with Ruby.
             And you can obtain more libraries via the package management system called

             Moreover there are thousands of Ruby projects in Rubyforge
             ( and RAA (


     Ruby interpreter accepts following command-line options (switches).  They are quite similar
     to those of perl(1).

     --copyright    Prints the copyright notice.

     --version      Prints the version of Ruby interpreter.

     -0[octal]      (The digit “zero”.)  Specifies the input record separator ($/) as an octal
                    number. If no digit is given, the null character is taken as the separator.
                    Other switches may follow the digits.  -00 turns Ruby into paragraph mode.
                    -0777 makes Ruby read whole file at once as a single string since there is no
                    legal character with that value.

     -C directory
     -X directory   Causes Ruby to switch to the directory.

     -E external[:internal]
     --encoding external[:internal]
                    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.

     -F pattern     Specifies input field separator ($;).

     -I directory   Used to tell Ruby where to load the library scripts.  Directory path will be
                    added to the load-path variable ($:).

     -K kcode       Specifies KANJI (Japanese) encoding. The default value for script encodings
                    (__ENCODING__) and external encodings (Encoding.default_external) will be the
                    specified one. kcode can be one of

                          e       EUC-JP

                          s       Windows-31J (CP932)

                          u       UTF-8

                          n       ASCII-8BIT (BINARY)

     -S             Makes Ruby use the PATH environment variable to search for script, unless if
                    its name begins with a slash.  This is used to emulate #! on machines that
                    don't support it, in the following manner:

                          #! /usr/local/bin/ruby
                          # This line makes the next one a comment in Ruby \
                            exec /usr/local/bin/ruby -S $0 $*

     -T[level=1]    Turns on taint checks at the specified level (default 1).

     -U             Sets the default value for internal encodings (Encoding.default_internal) to

     -W[level=2]    Turns on verbose mode at the specified level, without printing version
                    message at the beginning. The level can be;

                          0       Verbose mode is "silence". It sets the $VERBOSE to nil.

                          1       Verbose mode is "medium". It sets the $VERBOSE to false.

                          2 (default) Verbose mode is "verbose". It sets the $VERBOSE to true.
                                  -W2 is same as -w

     -a             Turns on auto-split mode when used with -n or -p.  In auto-split mode, Ruby
                          $F = $_.split
                    at beginning of each loop.

     -c             Causes Ruby to check the syntax of the script and exit without executing. If
                    there are no syntax errors, Ruby will print “Syntax OK” to the standard

     --debug        Turns on debug mode.  $DEBUG will be set to true.

     -e command     Specifies script from command-line while telling Ruby not to search the rest
                    of the arguments for a script file name.

     --help         Prints a summary of the options.

     -i extension   Specifies in-place-edit mode.  The extension, if specified, is added to old
                    file name to make a backup copy.  For example:

                          % echo matz > /tmp/junk
                          % cat /tmp/junk
                          % ruby -p -i.bak -e '$_.upcase!' /tmp/junk
                          % cat /tmp/junk
                          % cat /tmp/junk.bak

     -l             (The lowercase letter “ell”.)  Enables automatic line-ending processing,
                    which means to firstly set $\ to the value of $/, and secondly chops every
                    line read using chop!.

     -n             Causes Ruby to assume the following loop around your script, which makes it
                    iterate over file name arguments somewhat like sed -n or awk.

                          while gets

     -p             Acts mostly same as -n switch, but print the value of variable $_ at the each
                    end of the loop.  For example:

                          % echo matz | ruby -p -e '$! "a-z", "A-Z"'

     -r library     Causes Ruby to load the library using require.  It is useful when using -n or

     -s             Enables some switch parsing for switches after script name but before any
                    file name arguments (or before a --).  Any switches found there are removed
                    from ARGV and set the corresponding variable in the script.  For example:

                          #! /usr/local/bin/ruby -s
                          # prints "true" if invoked with `-xyz' switch.
                          print "true\n" if $xyz

                    On some systems $0 does not always contain the full pathname, so you need the
                    -S switch to tell Ruby to search for the script if necessary.  To handle
                    embedded spaces or such.  A better construct than $* would be ${1+"$@"}, but
                    it does not work if the script is being interpreted by csh(1).

     -v             Enables verbose mode.  Ruby will print its version at the beginning, and set
                    the variable $VERBOSE to true.  Some methods print extra messages if this
                    variable is true.  If this switch is given, and no other switches are
                    present, Ruby quits after printing its version.

     -w             Enables verbose mode without printing version message at the beginning.  It
                    sets the $VERBOSE variable to true.

     -x[directory]  Tells Ruby that the script is embedded in a message.  Leading garbage will be
                    discarded until the first that starts with “#!” and contains the string,
                    “ruby”.  Any meaningful switches on that line will applied.  The end of
                    script must be specified with either EOF, ^D (control-D), ^Z (control-Z), or
                    the reserved word __END__.  If the directory name is specified, Ruby will
                    switch to that directory before executing script.

     --yydebug      DO NOT USE.

                    Turns on compiler debug mode.  Ruby will print a bunch of internal state
                    messages during compiling scripts.  You don't have to specify this switch,
                    unless you are going to debug the Ruby interpreter.

                    Disables (or enables) the specified FEATURE.
                    --enable-gems      Disables (or enables) RubyGems libraries.  By default,
                                       Ruby will load the latest version of each installed gem.
                                       The Gem constant is true if RubyGems is enabled, false if

                    --enable-rubyopt   Ignores (or considers) the RUBYOPT environment variable.
                                       By default, Ruby considers the variable.

                    --enable-all       Disables (or enables) all features.

     --dump=target  DO NOT USE.

                    Prints the specified target.  target can be one of;

                          insns   disassembled instructions

                    You don't have to specify this switch, unless you are going to debug the Ruby

     --verbose      Enables verbose mode without printing version message at the beginning.  It
                    sets the $VERBOSE variable to true.  If this switch is given, and no other
                    switches are present, Ruby quits after printing its version.


     RUBYLIB         A colon-separated list of directories that are added to Ruby's library load
                     path ($:). Directories from this environment variable are searched before
                     the standard load path is searched.


     RUBYOPT         Additional Ruby options.

                           RUBYOPT="-w -Ke"

                     Note that RUBYOPT can contain only -d, -E, -I, -K, -r, -T, -U, -v, -w, -W,
                     --debug, --disable-FEATURE and --enable-FEATURE.

     RUBYPATH        A colon-separated list of directories that Ruby searches for Ruby programs
                     when the -S flag is specified.  This variable precedes the PATH environment

     RUBYSHELL       The path to the system shell command.  This environment variable is enabled
                     for only mswin32, mingw32, and OS/2 platforms.  If this variable is not
                     defined, Ruby refers to COMSPEC.

     PATH            Ruby refers to the PATH environment variable on calling Kernel#system.

     RUBYLIB_PREFIX  This variable is obsolete.

     And Ruby depends on some RubyGems related environment variables unless RubyGems is disabled.
     See the help of gem(1) as bellow.

           % gem help

SEE ALSO      The official web site.      hosting many open source ruby projects.      Ruby Application Archive.


     Security vulnerabilities should be reported via an email to ⟨⟩.
     Reported problems will be published after they've been 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 immediately.


     Ruby is designed and implemented by Yukihiro Matsumoto <>.

     See <> for contributors to Ruby.