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RUBY(1) 			 Ruby Programmers Reference Guide			  RUBY(1)

     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 (like 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 vari-
	     able 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 sin-
	     gleton methods, if you want to.

     Mix-in by modules
	     Ruby intentionally does not have the multiple inheritance as it is a source of con-
	     fusion.  Instead, Ruby has the ability to share implementations across the inheri-
	     tance 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, with-
	     out 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 on GitHub

     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.

		    Specify the default external or internal character encoding

     -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 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 the 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 '$_.tr! "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 and 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 line that starts with ``#!'' and contains the
		    string, ``ruby''.  Any meaningful switches on that line will be applied.  The
		    end of the script must be specified with either EOF, ^D (control-D), ^Z
		    (control-Z), or the reserved word __END__.	If the directory name is speci-
		    fied, 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 mes-
		    sages during compilation.  Only specify this switch 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

		    Only specify this switch if you are going to debug the Ruby interpreter.

     --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

     http://www.ruby-lang.org	   The official web site.
     http://www.rubyforge.org	   hosting many open source ruby projects.
     http://raa.ruby-lang.org	   Ruby Application Archive.
     https://github.com/languages/Ruby Ruby projects on Github.

     Security vulnerabilities should be reported via an email to <security@ruby-lang.org>.
     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
     (http://bugs.ruby-lang.org).  Do not report security vulnerabilities via the system because
     it publishes the vulnerabilities immediately.

     Ruby is designed and implemented by Yukihiro Matsumoto <matz@netlab.jp>.

     See <http://bugs.ruby-lang.org/wiki/ruby/Contributors> for contributors to Ruby.

UNIX					 November 7, 2012				     UNIX
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