Linking restrictions and shared libraries

John Cowan cowan at
Mon Mar 12 12:19:49 UTC 2001

Dr. David Gilbert scripsit:

> What I am unclear of is shared libraries; is there something actually
> copied into the result as part of the linking stage?  If I was to rewrite
> a header for a GPL library so that I didn't make use of the GPLd header
> could I then shared link it into a commercial app?

The FSF says no, but nobody knows for sure: when the GPL was written,
shared libraries were unheard-of.

> Can I write a commercial app which is not linked with a GPL library but
> opens it with dlopen at run time?

Arguably this does create a derived work, at least in memory, thus
violating the GPL.  (It is settled that the copy of a program
that you make in loading it from disk to memory *is* a copy, and
must be explicitly or implicitly licensed by the copyright owner.)

John Cowan                                   cowan at
One art/there is/no less/no more/All things/to do/with sparks/galore
	--Douglas Hofstadter

More information about the License-discuss mailing list