RUBY(1)                                                                UNIX                                                                RUBY(1)

NAME

       ruby - Interpreted object-oriented scripting language

SYNOPSIS

       ruby  [--copyright]  [--version]  [-Sacdlnpswvy]  [-0[octal]]  [-C  directory]  [-F pattern] [-I directory] [-K c] [-T[level]] [-e command]
       [-i[extension]] [-r library] [-x[directory]] [--] [program_file] [argument ...]

DESCRIPTION

       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.

FEATURES

       Ruby's features are as follows:

       Interpretive
              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  com-
              pile time check.

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

       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 collec-
              tor built into the interpreter.

       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.

       Class, inheritance, and methods
              Of course, as an object-oriented language, Ruby has such 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 `Mix-in'.

       Iterators
              Ruby has iterators for loop abstraction.

       Closures
              In Ruby, you can objectify the procedure.

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

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

       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-fly.

OPTIONS

       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
              Causes Ruby to switch to the directory.

       -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.

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

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

       -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.

       -d

       --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 arguments for a script file name.

       -h

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

       -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
                ...
              end

       -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"'
              MATZ

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

       -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/bin/ruby -s
              # prints "true" if invoked with `-xyz' switch.
              print "true
" 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

       --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.

       -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 reserved word __END__.  If the directory name is specified, Ruby will switch to that
              directory before executing script.

       -y

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

ENVIRONMENT

       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.

              e.g.:
                RUBYLIB="$HOME/lib/ruby:$HOME/lib/rubyext"

       RUBYOPT
              Additional Ruby options.

              e.g.
                RUBYOPT="-w -Ke"

       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 variable.

       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.

AUTHORS

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

December 31, 2002                                        Ruby Programmers Reference Guide                                                  RUBY(1)