Re: [Emc-developers] Spotted on Ali-Express (Via the forum)

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On Thu, Nov 05, 2015 at 07:44:41PM -0700, EBo wrote:
> Mach is one thing, but if they provide the source then are they not in 
> compliance?

On Fri, Nov 06, 2015 at 06:51:56AM -0600, Len Shelton wrote:
> Doesn't that also apply to PathPilot, then? Or is it okay to build a new 
> UI and rebrand it?

These are both cases of commercial, binary distribution.  This is
permitted under the GNU GPL version 2 as long as the requirements in
sections 2 and 3 are met.

In the case of commercial, binary distribution, merely saying "the
source code can be downloaded from linuxcnc.org" is not sufficient for
compliance.  Basically, the distributor must provide "complete
corresponding machine readable source code" for their "work based on the
Program" either by simply providing it at the same time the binary is
provided, or by offering to provide copies of the source code at cost to
anyone who requests it. (see particularly Section 3 items (a) and (b))

"Work based on the program" is not an entirely trivial concept to pin
down, but ultimately it includes whatever uses would have been
infringement under copyright law if not allowed by the GPL.

If your program cannot be built and used without doing one or more of
the following, then you probably should consider it a "Work based on [a
GPL] program":
    * Include a GPL source or header file to compile
    * Link with a library containing object code built from GPL
      files (static or dynamic linking)
    * Import a module, package, or component built from GPL
      source files (interpreted language counterpart to "linking")

If you are using a Debian system, the full text of the license is at
/usr/share/common-licenses/GPL-2.  I encourage you to read it for
yourself, it is not that long and tries to use plain language where
possible while still being a legal document.

If you plan to make a business that will copy and distribute software in
binary form, and even one piece of that software is GPL, then you should
retain a lawyer familiar with the issues surrounding the GPL and
copyright law in order to make sure you are in compliance.

Jeff