gnu readline licensing?

Robert Kern robert.kern at
Tue Apr 20 14:38:26 EDT 2010

On 4/20/10 1:09 PM, Brendan Miller wrote:
> Python provides a GNU readline interface... since readline is a GPLv3
> library, doesn't that make python subject to the GPL? I'm confused
> because I thought python had a more BSD style license.

The PSF License is more BSD-styled, yes. The readline module can also be 
built against the API-compatible, BSD-licensed libedit library. Python's 
source distribution (even the readline module source) does not have to 
be subject to the GPL, though it should be (and is) GPL-compatible.

> Also, I presume programs written with the readline interface would
> still be subject to GPL... might want to put a warning about that in
> the python library docs.

*When* someone builds a binary of the Python readline module against the 
GNU readline library, then that binary module is subject to the terms of 
the GPL. Any programs that distribute with and use that binary are also 
subject to the terms of the GPL (though it can have a non-GPL, 
GPL-compatible license like the PSF License). This only applies when 
they are combined with the GNU readline library, not before. The program 
must have a GPL-compatible license in order to be distributed that way. 
It can also be distributed independently of GNU readline under any license.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though 
it had
  an underlying truth."
   -- Umberto Eco

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