My program calls one function on a GPL'ed program - do I have to distribute under terms of GPL?

Question

I am working on an iPhone application and understand some difficulties in releasing a GPL application through the app store.

The license states that a program forking-and-linking to another program licensed under the GPL doesn't attach any requirements to that program. Moreover, it also says

"If the program dynamically links plug-ins, but the communication between them is limited to invoking the ‘main’ function of the plug-in with some options and waiting for it to return, that is a borderline case."

My program essentially calls a main function of a GPL'd program, and uses the output file of that function to retrieve its data. Therefore, this would be a "borderline" case as described by gnu.org.

This condition leaves the situation at an undefined point. Is there a way to circumvent the restrictions of the GNU in this case?

Free software is great, but for an iPhone application with Apple as the distributor, it simply adds hassle.

Answer 1

IANAL, but if you just call the other program (and it is still a separate executable file) and process the output, the GPL is not a problem at all. Just remember that when you distribute that GPLed program, you must comply to the GPL regarding to that program, i.e. you must offer the source code for that program etc.