NAME
rruubbyy - Interpreted object-oriented scripting language
SYNOPSIS
rruubbyy [--ccooppyyrriigghhtt] [--vveerrssiioonn] [-SSaaccddllnnppsswwvvyy] [-00[octal]] [-CC directory]
[-FF pattern] [-II directory] [-KK c] [-TT[level]] [-ee command]
[-ii[extension]] [-rr library] [-xx[directory]] [--] [programfile]
[argument ...]
DESCRIPTION
Ruby is an interpreted scripting language for quick and easy object-ori-
ented 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.
FFEEAATTUURREESS
Ruby's features are as follows:
IInntteerrpprreettiivvee
Ruby is an interpreted language, so you don't have to recompile
programs written in Ruby to execute them.
VVaarriiaabblleess hhaavvee nnoo ttyyppee ((ddyynnaammiicc ttyyppiinngg))
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.
NNoo ddeeccllaarraattiioonn nneeeeddeedd
You can use variables in your Ruby programs without any declara-
tions. Variable names denote their scope, local, global,
instance, etc.
SSiimmppllee ssyynnttaaxx
Ruby has a simple syntax influenced slightly from Eiffel.
NNoo uusseerr-lleevveell mmeemmoorryy mmaannaaggeemmeenntt
Ruby has automatic memory management. Objects no longer refer-
enced from anywhere are automatically collected by the garbage
collector built into the interpreter.
EEvveerryytthhiinngg iiss aann oobbjjeecctt
Ruby is the purely object-oriented language, and was so since its
creation. Even such basic data as integers are seen as objects.
CCllaassss,, iinnhheerriittaannccee,, aanndd mmeetthhooddss
Of course, as an object-oriented language, Ruby has such basic
features like classes, inheritance, and methods.
SSiinngglleettoonn mmeetthhooddss
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 meth-
ods, if you want to.
MMiixx-iinn bbyy mmoodduulleess
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'.
IItteerraattoorrss
Ruby has iterators for loop abstraction.
CClloossuurreess
In Ruby, you can objectify the procedure.
TTeexxtt pprroocceessssiinngg aanndd rreegguullaarr eexxpprreessssiioonn
Ruby has a bunch of text processing features like in Perl.
BBiiggnnuummss
With built-in bignums, you can for example calculate facto-
rial(400).
EExxcceeppttiioonn hhaannddlliinngg
As in Java(tm).
DDiirreecctt aacccceessss ttoo tthhee OOSS
Ruby can use most UNIX system calls, often used in system pro-
gramming.
DDyynnaammiicc llooaaddiinngg
On most UNIX systems, you can load object files into the Ruby
interpreter on-the-fly.
OOPPTTIIOONNSS
Ruby interpreter accepts following command-line options (switches). They
are quite similar to those of perl(1).
--ccooppyyrriigghhtt Prints the copyright notice.
--vveerrssiioonn Prints the version of Ruby interpreter.
-00[octal] (The digit ``zero''.) Specifies the input record separa-
tor ($/) as an octal number. If no digit is given, the
null character is taken as the separator. Other switches
may follow the digits. -0000 turns Ruby into paragraph
mode. -00777777 makes Ruby read whole file at once as a sin-
gle string since there is no legal character with that
value.
-CC directory Causes Ruby to switch to the directory.
-FF pattern Specifies input field separator ($;).
-II directory Used to tell Ruby where to load the library scripts.
Directory path will be added to the load-path variable
($:).
-KK kcode Specifies KANJI (Japanese) encoding.
-SS 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 $*
-TT[level] Turns on taint checks at the specified level (default 1).
-aa Turns on auto-split mode when used with -nn or -pp. In
auto-split mode, Ruby executes
$F = $.split
at beginning of each loop.
-cc 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.
-dd
--ddeebbuugg Turns on debug mode. $DEBUG will be set to true.
-ee command Specifies script from command-line while telling Ruby not
to search the rest of arguments for a script file name.
-hh
--hheellpp Prints a summary of the options.
-ii extension Specifies in-place-edit mode. The extension, if speci-
fied, is added to old file name to make a backup copy.
For example:
% echo matz > /tmp/junk
% cat /tmp/junk
matz
% ruby -p -i.bak -e '$.upcase!' /tmp/junk
% cat /tmp/junk
MATZ
% cat /tmp/junk.bak
matz
-ll (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!.
-nn Causes Ruby to assume the following loop around your
script, which makes it iterate over file name arguments
somewhat like sseedd -nn or aawwkk.
while gets
...
end
-pp 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
-rr library Causes Ruby to load the library using require. It is use-
ful when using -nn or -pp.
-ss 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 path-
name, so you need the -SS 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).
-vv
--vveerrbboossee 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.
-ww Enables verbose mode without printing version message at
the beginning. It sets the $VERBOSE variable to true.
-xx[directory] Tells Ruby that the script is embedded in a message.
Leading garbage will be discarded until the first that
starts with ``#!'' and contains the string, ``ruby''. Any
meaningful switches on that line will applied. The end of
script must be specified with either EOF, ^D (control-D),
^Z (control-Z), or reserved word END. If the direc-
tory name is specified, Ruby will switch to that directory
before executing script.
-yy
--yyyyddeebbuugg Turns on compiler debug mode. Ruby will print a bunch of
internal state messages during compiling scripts. You
don't have to specify this switch, unless you are going to
debug the Ruby interpreter.
ENVIRONMENT RUBYLIB A colon-separated list of directories that are appended
to Ruby's library load path ($:).
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 -SS 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.
RUBYLIBPREFIX This variable is obsolete.
AUTHORS Ruby is designed and implemented by Yukihiro Matsumoto .
UNIX December 31, 2002 UNIX