On 31/07/2025 09:36, Thomas Wolff via Cygwin-apps wrote:
Am 30.07.2025 um 20:22 schrieb Jon Turney via Cygwin-apps:
On 28/07/2025 14:01, Matthew Sheets via Cygwin-apps wrote:
I've been poking around at what might be needed to facilitate a
portable Cygwin setup, and registry activity is one of the aspects
that would need to be addressed.
Are there any flags, options, special environment variables, etc.
that would prevent Cygwin from making any registry changes?
Cygwin FAQ 2.24 states the following:
"Cygwin doesn't store anything important in the registry anymore for
quite some time. There's no reason to save, restore or delete it."
- https://www.cygwin.com/faq.html#faq.setup.registry
After a fresh install to a clean system with a recent CygwinSetup-
x86_64.exe (June 30), registry entries like the following can be found:
[HKEY_CURRENT_USER\SOFTWARE\Cygwin\Installations]
"e022582115c10879"="\\??\\C:\\cygwin64"
[HKEY_LOCAL_MACHINE\SOFTWARE\Cygwin\Installations]
"e022582115c10879"="\\??\\C:\\cygwin64"
These are records of the "installation key", a hash of the path Cygwin
is installed in (which is, um, added to the names of internal objects
to so that multiple cygwin installations are isolated from each other,
or something like that)
This is written to the registry by the DLL, purely for informational
purposes, I think.
> [HKEY_LOCAL_MACHINE\SOFTWARE\Cygwin\setup]
"rootdir"="C:\\cygwin64"
This last registry entry is written by setup.This is only used to
store the selected installation root directory, so that setup can
default to it, next time you run it.
It may also confuse setup as I reported some months ago. With two
installations (one for testing), setup was permantly switched to
proposing the test root, even after installing for the main working
installation again.
I'd suggest to drop this registry writing (i.e. make --no-write-registry
the default). Setup should check whether it's being called from within a
cygwin installation tree and use that, or fallback to the default.
No, I don't think it's a good idea to make the typical use case worse
(user has one cygwin installation) in order to perhaps improve the edge
case (user has multiple cygwin installations).
And if adding this option does make things work the way you want (which
seems to be just an assertion at this point, since you're not actually
reporting that you tested it and it does), you could always do that?
