Ruby is copyrighted free software by Yukihiro Matsumoto <matz@netlab.jp>.
You can redistribute it and/or modify it under either the terms of the
2-clause BSDL (see the file BSDL), or the conditions below:

1. You may make and give away verbatim copies of the source form of the
   software without restriction, provided that you duplicate all of the
   original copyright notices and associated disclaimers.

2. You may modify your copy of the software in any way, provided that
   you do at least ONE of the following:

     a) place your modifications in the Public Domain or otherwise
        make them Freely Available, such as by posting said
        modifications to Usenet or an equivalent medium, or by allowing
        the author to include your modifications in the software.

     b) use the modified software only within your corporation or
        organization.

     c) rename any non-standard executables so the names do not conflict
         with standard executables, which must also be provided.

     d) make other distribution arrangements with the author.

3. You may distribute the software in object code or executable
   form, provided that you do at least ONE of the following:

     a) distribute the executables and library files of the software,
        together with instructions (in the manual page or equivalent)
        on where to get the original distribution.

     b) accompany the distribution with the machine-readable source of
        the software.

     c) give non-standard executables non-standard names, with
        instructions on where to get the original software distribution.

     d) make other distribution arrangements with the author.

4. You may modify and include the part of the software into any other
   software (possibly commercial). But some files in the distribution
   are not written by the author, so that they are not under this terms.

   They are gc.c(partly), utils.c(partly), regex.[ch], st.[ch] and some
   files under the ./missing directory. See each file for the copying
   condition.

5. The scripts and library files supplied as input to or produced as
   output from the software do not automatically fall under the
   copyright of the software, but belong to whomever generated them,
   and may be sold commercially, and may be aggregated with this
   software.

6. THIS SOFTWARE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR
   IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE. 

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1) Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.

2) Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.