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RedHat 9 (Linux i386) - man page for ruby (redhat section 1)

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

       ruby - Interpreted object-oriented scripting language

       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 ] ...

       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.

       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 compile 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 collector 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 sin-
	      gleton methods, if you want to.

       o 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 `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-

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

	      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 dig-
	      its.  -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.

	      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

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

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

	      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

       -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"'

       -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\n" 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 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.

       -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.

	      turns on taint checks at the specified level (default 1).

	      prints the version of Ruby interpreter.

       -w     enables verbose mode without printing version message at the beginning. It set the
	      `$VERBOSE' variable to true.

	      tells Ruby that the script is embedded in a message. Leading garbage will be dis-
	      carded 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

       -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.

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

2001-12-25				     ruby 1.6					  RUBY(1)

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