rsync - Mar 2005 - files' timestamp handling - bug or design decision?

Hello,

A few days ago I posted a question about handling timestamps in rsync
(Q: rsync - preserve timestamps, but not use it to define files to
update), but did not get a single response, so I thought I'd rephrase
it. Also, with a new release of rsync out, may be there is some more
time that knowledgeable people have :-) So here it goes.

I want to be able to do two things together:
-- transfer files from the source to destination only if the files'
contents is changed
-- when the files are transfered, I want to preserve original timestamp

The first item is taken care by --size-only and --checksum
The second - by --times. However, when the two are combined, the
destination gets updated whenever the files in the source are touched.

I have a directory, where some tool creates files - database exports,
for example. I want to check in these exports into a source control,
which is timestamp sensitive and I do not want to create a new version
every time the file is exported. So I have a staging area, where the
data gets exported from the database, and I want to update my source
control work area from the staging, but transfer only files, which
actually changed.

By looking at the switches available in rsync, I assumed that a
combination of --times and --checksum would do what I want, but
apparently, --times not only tells rsync to preserve timestamps on
transfer, but also to consider the files for the transfer if there is
a discrepancy in the mtime of the files.

You help is highly appreciated.

Eugene.

On Wed, Mar 30, 2005 at 09:16:03PM -0800, Eugene Kramer
wrote:
> However, when the two are combined, the destination gets updated
> whenever the files in the source are touched.
Just to be clear, the timestamp gets changed, though the file is not
transferred due to the --checksum option (the --size-only option has no
effect with --checksum).  Rsync always brings the destination in sync
with the source with whatever attributes you've told it to preserve, so
what you're trying to do won't work.

..wayne..

> I want to be able to do two things together:
> -- transfer files from the source to destination only if the files'
> contents is changed
rsync -avr

Consider: -W -x --delete --delete-excluded --log-format='%i %f'

Use --dry-run when testing for the right configuration to avoid data loose.
> -- when the files are transfered, I want to preserve original timestamp
Try -a.
> By looking at the switches available in rsync, I assumed that a
> combination of --times and --checksum would do what I want, but
> apparently, --times not only tells rsync to preserve timestamps on
> transfer, but also to consider the files for the transfer if there is
> a discrepancy in the mtime of the files.
rsync's defaults is pretty sane, and does what you want in most cases. Try
rsync -avr --dry-run
and see, if this doesn't solve your needs.