Re: pax and ext2fs

On 2024-05-02, Walter Alejandro Iglesias <wai@roquesor.com> wrote:
> I expect from that command no more and no less than what is explained in
> the man page:
>
> Update (and list) only those files in the destination directory
> /backup which are older (less recent inode change or file
> modification times) than files with the same name found in the source
> file tree home:
>
> $ pax -r -w -v -Y -Z home /backup
>
> While that works as explained when copying to a ffs drive, running the
> same command again and again to a ext2fs target *all* files are copied
> again, even those already updated, what suggests me that pax(1) fails to
> get ext2fs timestamps right.

I don't have a suitable filesystem handy to test, but does OpenBSD's
implementation of ext2fs support sub-second timestamps?

stat -f %Fm $filename

If not, that's a probable explanation for the difference in behaviour.
You could probably confirm by forcing timestamps with no nanosecond
components, e.g. touch -t yyyymmddhhmm.ss $filename, or copy to ext2fs
and back again.

> But this is asking to much to OpenBSD,
> right? Linux don't even support ffs. That's why I didn't put much care
> in reporting this issue or sending it to bugs@.

By reporting an issue, you're implicitly asking people to spend some
time looking at it. So, if it's worth reporting at all, it's worth putting
a bit more effort in yourself.