recommendations for 3rd party distributors?

Christopher Faylor
Mon Feb 14 21:37:00 GMT 2005

On Mon, Feb 14, 2005 at 09:54:41AM -0500, Dick Repasky wrote:
>Every so often a query surfaces about cygwin dll version compatibility.
>What would be useful is a set of recommendations that can be used by 3rd 
>party distributors of the cygwin dll to minimize the chance of version 
>collisions with installed instances of cygwin and with other 3rd party 
>software that is distributed with cygwin dlls.  Everyone should benefit 
>from a set of recommendations: cygwin users will have fewer problems,
>3rd party distributors will have fewer problems, and cygwin mailing list 
>subscribers will have less mail.
>After searching the mailing list archives and finding Igor Pechtchanski's 
>post (, reading the 
>source code, tinkering and testing, I've come up with a list.  I ask 
>readers of the cygwin mailing list for comments and suggestions.  Are 
>there errors in the list that I do not see?  Do you have suggestions for 
>improving the list?
>The recommendations are:
>  1) Use a distinctly named shared memory area in the cygwin dll.
>  2) Use a distinctly named registry key for storing cygwin file system
>     mount points.
>  3) Identify the origin of the cygwin dll in the cygwin dll.

Your archive searching couldn't have been too comprehensive if you think
we want to get into ways of doing this.

There are no recommendations for changing the cygwin dll.

>These changes work under the conditions that I have tested them.
>Comments?  Suggestions?

You haven't done much testing if you think those will work.  You seem to
have missed command line interactions.

If you are a 3rd party distributor, you should check for existing
installations of the dll.  If the existing version of cygwin DLL is the
same or newer than the one you want to use, then notify the user that
there is already a version on the system and that you will not be
installing a new version.

Otherwise, install your version in a standard location so that it will
survive being upgraded if a user decides to upgrade.

And, of course, unless this is a distribution which is internal to your
organization, remember to offer the user the source code to whatever
application you're providing to them.

I work for a company which distributes cygwin in the way that I've
outlined and, to the best of my knowledge, we have not had any problems
with this technique.


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