RUBY(1) 						 Ruby Programmers Reference Manual						   RUBY(1)

NAME

       ruby - Interpreted object-oriented scripting language

SYNOPSIS

       ruby   [ --version ]  [ -c ]  [ -w ]  [ -d ]  [ -l ]
	      [ -p ]  [ -n ]  [ -a ]  [ -s ]  [ -0[octal] ]
	      [ -Kc ]  [ -ecommand ]  [ -Fpattern ]
	      [ -i[extension] ]  [ -Idir ] [ -rlibrary ]
	      [ -S ]  [ -v ]  [ -x[directory] ]  [ -Cdirectory ]
	      [ -y] [ -- ] [ programfile ]  [ argument ] ...

PREFACE

       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 much parentheses, Ruby may be the language of your choice.

DESCRIPTION

       Ruby's features are as follows:

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

       o 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 com-
	      pile time check.

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

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

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

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

       o Class, inheritance, methods
	      Of course, as an object-oriented language, Ruby has such basic features like classes, inheritance, and methods.

       o 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.

       o 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 `Mix-in'.

       o Iterators
	      Ruby has iterators for loop abstraction.

       o Closures
	      In Ruby, you can objectify the procedure.

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

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

       o Exception handling
	      As in Java(tm).

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

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

COMMAND LINE OPTIONS

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

       -0[octal]
	      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.

       -a     turns on auto-split mode when used with -n or -p. In auto-split mode, Ruby executes
		  $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 output.

       --copyright
	      prints the copyright notice.

       -d --debug
	      turns on debug mode. $DEBUG will set true.

       -e command
	      specifies script from command-line while telling Ruby to not search argv for script filenames.

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

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

       -i extension
	      specifies in-place-edit mode. The extension, if specified, is added to old filename to make a backup copy.  example:
		  % echo matz > /tmp/junk
		  % cat /tmp/junk
		  matz
		  % ruby -p -i.bak -e '$_.upcase!' /tmp/junk
		  % cat /tmp/junk
		  MATZ
		  % cat /tmp/junk.bak
		  matz

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

       -Kkcode
	      specifies KANJI (Japanese) encoding.

       -l     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 filename arguments somewhat like sed -n or
	      awk.
		  while gets
		    ...
		  end

       -p     acts mostly same as -n switch, but print the value of variable $_ at the each end of the loop.  example:
		  % echo matz | ruby -p -e '$_.tr! "a-z", "A-Z"'
		  MATZ

       -r library
	      causes Ruby to load the library using require. It is useful with switches -n or -p.

       -s     enables some switch parsing for switches after script name but before any filename arguments (or before a --). Any switches found
	      there are removed from ARGV and set the corresponding variable in the script.  example:
		  #! /usr/local/bin/ruby -s
		  # prints "true" if invoked with `-xyz' switch.
		  print "true
" if $xyz

       -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 $*
	      On some systems $0 does not always contain the full pathname, so you need -S switch to tell Ruby to search for the script if neces-
	      sary.  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.

       -v --verbose
	      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.

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

       --version
	      prints the version of Ruby interpreter.

       -w     enables verbose mode without printing version message at the beginning. It set 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 reserved word __END__.If the directory name is specified, Ruby will switch to that directory
	      before executing script.

       -C directory
	      causes Ruby to switch to the directory.

       -y --yydebug
	      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.

AUTHOR

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

2001-12-25							     ruby 1.6								   RUBY(1)