jruby(1) Interpreted object-oriented scripting language


[--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 ... ]


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.


Ruby interpreter accepts following command-line options (switches). They are quite similar to those of perl(1).

Prints the copyright notice.

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.

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).

Turns on auto-split mode when used with -n or -p In auto-split mode, Ruby executes
$F = $_.split
at beginning of each loop.

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.

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.

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

(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!

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

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"'

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

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).

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.

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.

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.