NAME

     jruby — Interpreted object-oriented scripting language

SYNOPSIS

     jruby [--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

     Jruby is a 100% pure-Java implementation of Ruby, 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.

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/local/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/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 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 specify this switch,
                    unless you are going to debug the Ruby interpreter.