environment variables & mks toolkit - patch opportunity?

Christopher Faylor cgf-use-the-mailinglist-please@cygwin.com
Wed Jul 25 22:54:00 GMT 2012

On Wed, Jul 25, 2012 at 05:43:52PM -0500, M. Sebastian Comella wrote:
>Hi all -
>I recently lost a good chunk of my day tracking down a Cygwin issue
>ultimately caused by an installation of IBM InfoSphere. The InfoSphere
>installer surreptitiously installed MKS Toolkit, which in turn set a
>bunch of environment variables that left Cygwin in a very unhelpful
>state: attempting to start Cygwin via its usual mintty shortcut would
>appear to hang, with mintty showing "sh.exe" in its title bar and
>little else. The cause of the issue is unfortunately not very obvious
>since there is no error message or other form of reporting. If I had
>realized that MKS Toolkit was being installed I might have had a
>fighting chance, but without that info I was in the dark.
>Fortunately, fixing the issue is pretty easy and is a matter of
>removing some Windows environment variables, as noted in this
>2002-vintage thread:
>My question is this: is there an opportunity to patch something in
>Cygwin's startup "chain" to detect unsavory environment variables and
>warn users in some fashion? I'm not sure what package (or core
>process) could detect the situation and still get a warning off to the
>user before everything goes fubar. Putting a check into the installer
>may also be a viable solution, considering that the first thing I did
>was run the Cygwin installer again to see if it could "repair" things.
>I think I can take care of writing the patch, but I'd like some input
>on where it even belongs before I give it a shot.

If you can provide an exact environment variable which caused a problem
we can look into whether this is actually a problem in Cygwin, although
it seems unlikely that it is.  Cygwin is meant to read environment
variables from...  its environment.  If you set them incorrectly bad
things can happen.  Cygwin is no different than UNIX in that regard.

We're can't add special case handling for a bunch of random environment
variables because someone reported that they think they might have
caused a problem.  We need more details than that.


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