On Wed, 2008-10-22 at 14:38 +0200, Michal Soltys wrote:
> A good while ago I asked about difference between --delete-during/delay
> and --delete-after, when per-directory files are updated (all is
> perfectly clear for me here), but during the discussion there was a hint
> made by Wayne, that the outcome can differ in more situations:
> " It is useful for things such as --delay-updates --delete-delay (to
> have all updates happen more rapidly at the end), and the option avoids
> an extra dir-scan delete pass in such a case. And for folks that don't
> have per-dir filter files being updated, it works the same as
> --delete-after (if we disregard certain backup-file cases where the
> suffix is not excluded), just more optimally. "

(It would have made my life easier if you had replied directly to that
message so I didn't have to search for it.)

> If I understand it correctly - those "backup-file cases" mean -b option
> and - accidental or deliberate - override of the protect rule added
> implicitly by rsync (as explained in the man page). But if this rule is
> overriden (effectivly allowing deletion of backuped files), then
> assuming no per-dir rules are changed, the outcome will be the same
> regardless if we use --delete-during + --delete-delay or --delete-after.

I found one case where the outcome differs. If the protect filter is
overridden and a destination file is backed up before being *updated*,
then --delete-after will delete the backup file but --delete-delay won't
(because it checks for deletions before the backup file is created in
the first place). E.g., with this sequence of commands:

mkdir src dest
touch dest/foo
echo NEWDATA >src/foo
rsync -r --delete-WHEN --filter='R *' -b src/ dest/

dest/foo~ will exist at the end if WHEN is "delay" but not if WHEN is

I can't think of any other such cases when no per-dir rules are changed,
but that doesn't mean there aren't any: an rsync run is a complex
process with numerous steps that can interact in unexpected ways.


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