update with apt-cyg ?

[Hans-Bernhard Bröker]

Am 07.09.2020 um 01:00 schrieb Ulli Horlacher:

> cygstart /setup-x86_64.exe --quiet-mode

That approach is essentially guaranteed to fail you in frustrating ways, 
for two reasons:

1) (Minor) You do not want to have setup itself, much less its work and 
data directory, inside the cygwin installation.  I.e. that should never 
be '/' as the path for setup, as seen from any Cygwin shell.

2) (Major) Updating a running cygwin installation from the inside is 
highly unlikely to work correctly.  Most importantly there is almost no 
chance for it to update the core DLLs, because those will already be in 
use by the shell you're running this from, so they cannot be changed. 
I.e. if you're in a situation where using "cygstart" makes any sense, 
that's a situation setup cannot update the DLLs.

In a nutshell, and to paraphrase a certain Mr. Ford, you can have your 
special non-interactive Cygwin setup script in any language you like, as 
long as it's effectively a _Windows_ batch file.  Updating the branch 
you're currently sitting on does not work any better than sawing it through.