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Re: Distributing GPL software

Your questions about what makes a work "derived" from a GPLed work are
good questions.  Unfortunately, laws are not uniform on this; in the
US, there are two or three different ways to analyze whether one work
is derived from another copyrighted work, and I imagine most other
countries have their own rules (at least slightly different from the
US's) to determine this.  In the case of a shell script, the point is
likely moot because the script is its own source code.

Török Edvin writes:

> To be "safe", and not violate the GPL, which of the following should I do:
> - A link to where the original sources can be downloaded from
> - Include the sources of xpdf/xdialog
> - Host the sources of xpdf/xdialog on the company's webserver
> Should I also:
> - Write a statement in a README/COPYRIGHT file, enumerating the
> included GPL software, and their copyright
> - Contact upstream, to let them know we use their software

The GPL specifically disallows the first option for commercial
distribution unless you are the one hosting the source code (and you
provide it for at least three years after your most recent
distribution of binary files).  The easiest way to satisfy the GPL is
to include the complete source code for the GPLed works that you
distribute on the CD, which I think is your second option.

Whichever option you choose, you must include a copy of the GPL on the
CD and identify the GPLed software.  Notifying the upstream maintainer
is polite but not required by the GPL.

> P.S.:
> If I make changes to a GPL program, is it enough if I submit the
> changes upstream, or do I have to offer the patch (on the CD/on the
> web)?

Neither by itself satisfies the GPL.  The GPL requires that the
binary-code recipient (be able to) get the complete modified source

Michael Poole

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