command-line calls of GPL'd executables

Paul Cody Johnston pcj at
Sun Jul 15 07:39:28 UTC 2001

* phil hunt (philh at wrote:
> Consider this situation:
> Alice writes a program, aprog, which she licenses under the GPL.

First of all, don't assume my answer is correct, I've just begun to
get involved in these discussions, but it's something I think is

> Bob writes another program, which invokes the aprog executable,
> using the POSIX system() call. Does Bob's program have to be
> released under a GPL-compatible license?

I don't think so.  This is not considered linking which I believe is
the criterion.

> (Assume for the sake of argument that there is no other program
> that does the same as aprog).
> What if aprog is, instead, licensed under the BSDL with advertising
> clause. Can be GPL his program?

Same thing I think.  In my opinion, sharing state between applications
does not complicate licensing issues.  If that were the case, then
every piece of software the uses TCP/IP or http could be considered
"the same program", and what a mess that would be.

Sharing code is another matter.  If the application shares
instructions, then the license is an issue.

But like most things when I open my trap prematurely, I'm wrong.


> --
> #===== Philip Hunt == philh at ======#
>     Herbivore: effort-free public key encryption. See:
> <>

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