ruby/ruby.1

.\"Ruby is copyrighted by Yukihiro Matsumoto <matz@netlab.jp>.
.na
.TH RUBY 1 "ruby 1.6" "2000-09-11" "Ruby Programmers Reference Guide"
.SH NAME
ruby - Interpreted object-oriented scripting language
.SH SYNOPSIS
.B ruby \c
  [ \c
.BI --version \c
 ]  [ \c
.BI -c \c
 ]  [ \c
.BI -w \c
 ]  [ \c
.BI -d \c
 ]  [ \c
.BI -l \c
 ]
       [ \c
.BI -p \c
 ]  [ \c
.BI -n \c
 ]  [ \c
.BI -a \c
 ]  [ \c
.BI -s \c
 ]  [ \c
.BI -0 "[octal]"\c
 ]
       [ \c
.BI -K "c"\c
 ]  [ \c
.BI -e "command"\c
 ]  [ \c
.BI -F "pattern"\c
 ]
       [ \c
.BI -i "[extension]"\c
 ]  [ \c
.BI -I "dir"\c
 ] [ \c
.BI -r "library"\c
 ]
       [ \c
.BI -S \c
 ]  [ \c
.BI -v \c
 ]  [ \c
.BI -x "[directory]"\c
 ]  [ \c
.BI -C "directory"\c
 ]
       [ \c
.BI -y \c
] [ \c
.BI -- \c
 ] [ programfile ]  [ argument ] ...

.SH 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.
.PP
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.
.SH DESCRIPTION
Ruby's features are as follows:
.TP
.B "\(bu Interpretive"
Ruby is an interpreted language, so you don't have to recompile
programs written in Ruby to execute them.
.TP
.B "\(bu 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.
.TP
.B "\(bu No declaration needed"
You can use variables in your Ruby programs without any declarations.
Variable names denote their scope, local, global, instance, etc.
.TP
.B "\(bu Simple syntax"
Ruby has a simple syntax influenced slightly from Eiffel.
.TP
.B "\(bu 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.
.TP
.B "\(bu 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.
.TP
.B "\(bu Class, inheritance, methods"
Of course, as an object-oriented language, Ruby has such basic
features like classes, inheritance, and methods.
.TP
.B "\(bu 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.
.TP
.B "\(bu 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'.
.TP
.B "\(bu Iterators"
Ruby has iterators for loop abstraction.
.TP
.B "\(bu Closures"
In Ruby, you can objectify the procedure.
.TP
.B "\(bu Text processing and regular expression"
Ruby has a bunch of text processing features like in Perl.
.TP
.B "\(bu Bignums"
With built-in bignums, you can for example calculate factorial(400).
.TP
.B "\(bu Exception handling"
As in Java(tm).
.TP
.B "\(bu Direct access to the OS"
Ruby can use most UNIX system calls, often used in system programming.
.TP
.B "\(bu Dynamic loading"
On most UNIX systems, you can load object files into the Ruby
interpreter on-the-fly.
.PP
.SH COMMAND LINE OPTIONS
Ruby interpreter accepts following command-line options (switches).
They are quite similar to those of Perl.
.TP
.B -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.
.TP
.B -a
turns on auto-split mode when used with -n or -p. In auto-split
mode, Ruby executes
.nf
.ne 1
\&    $F = $_.split
at beginning of each loop.
.fi
.TP
.B  -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.
.TP
.B --copyright
prints the copyright notice.
.TP
.B -d --debug
turns on debug mode. $DEBUG will set true.
.TP
.B -e command
specifies script from command-line while telling Ruby to not
search argv for script filenames.
.TP
.B -F pattern
specifies input field separator ($;).
.TP
.B -h --help
prints a summary of the options.
.TP
.B -i extension
specifies in-place-edit mode. The extension, if specified, is
added to old filename to make a backup copy.
example:
.nf
.ne 8
\&    % echo matz > /tmp/junk
\&    % cat /tmp/junk
\&    matz
\&    % ruby -p -i.bak -e '$_.upcase!' /tmp/junk
\&    % cat /tmp/junk
\&    MATZ
\&    % cat /tmp/junk.bak
\&    matz
.fi
.TP
.B -I directory
used to tell Ruby where to load the library scripts. Directory path
will be added to the load-path variable ($:').
.TP
.B -Kkcode
specifies KANJI (Japanese) encoding.
.TP
.B -l
enables automatic line-ending processing, which means to firstly set
$\e to the value of $/, and secondly chops every line read using chop!.
.TP
.B -n
causes Ruby to assume the following loop around your script,
which makes it iterate over filename arguments somewhat like
sed -n or awk.
.nf
.ne 3
\&    while gets
\&      ...
\&    end
.fi
.TP
.B -p
acts mostly same as -n switch, but print the value of variable
$_ at the each end of the loop.
example:
.nf
.ne 2
\&    % echo matz | ruby -p -e '$_.tr! "a-z", "A-Z"'
\&    MATZ
.fi
.TP
.B -r library
causes Ruby to load the library using require. It is useful
with switches -n or -p.
.TP
.B -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:
.nf
.ne 3
\&    #! /usr/local/bin/ruby -s
\&    # prints "true" if invoked with `-xyz' switch.
\&    print "true\en" if $xyz
.fi
.TP
.B -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:
.nf
.ne 2
\&    #! /usr/local/bin/ruby
\&    # This line makes the next one a comment in ruby \e
\&      exec /usr/local/bin/ruby -S $0 $*
.fi
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.
.TP
.B -v --verbose
enables verbose mode. Ruby will print its version at the beginning,
and set the variable `$VERBOSE' to true. Some methods print extra
messages if this variable is true. If this switch is given, and no
other switches are present, Ruby quits after printing its version.
.TP
.B -T[level]
turns on taint checks at the specified level (default 1).
.TP
.B --version
prints the version of Ruby interpreter.
.TP
.B -w
enables verbose mode without printing version message at the
beginning. It set the `$VERBOSE' variable to true.
.TP
.B -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.
.TP
.B -C directory
causes Ruby to switch to the directory.
.TP
.B -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.
.PP
.SH AUTHOR
 Ruby is designed and implemented by Yukihiro Matsumoto <matz@netlab.jp>.