Re: tramp (2.5.0-pre nil/nil); Cannot write to /sudo::file in /boot partition

[Yikai Zhao]

Beside of getting the error message, the buffer will also remain in "unsaved" 
state which is annoying because emacs will then warn me when I close it.

I think this should be a fairly common use case (everyone's boot partition must 
be a FAT filesystem, right?) and it would be great to see it resolved by tramp.

Can we maybe detect this kind of error (by parsing the output of cp?) to ignore 
it? Or can we detect the destination filesystem type to drop the "-p" argument 
of cp? Or, at the very least, can we have a buffer-local option to control the 
arguments of the cp command?

On Mon, Dec 21, 2020, at 22:25, Michael Albinus wrote:
> "Yikai Zhao" <i@blahgeek.com> writes:
> 
> Hi,
> 
> > OK I think I got it:
> >
> > # sudo cp -f -p init.el /boot/init.el
> > cp: failed to preserve ownership for '/boot/init.el': Operation not 
> > permitted
> >
> > cp returned non-zero code because the FAT filesystem (/boot) does not
> > support file ownership etc (required by the -p argument). However the
> > file actually get successfully copied.
> 
> So likely, there isn't too much Tramp can do. Live with that error.
> 
> Best regards, Michael.
>