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Old 11-23-2012, 09:32 AM   #1
Registered: Feb 2008
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rsync without copying files when the only difference is the time time

How to ask rsync not to copy files from A to B when the only difference is
in the creation time and probably permission ?

I have this problem when I used scp rather than rsync to copies files.
Later when I tried to rsync -av --delete, it seems I have to redo what scp has done just
because the time stamp is different ! Imagine I spend hours to scp
the huge across different platforms.

Old 11-23-2012, 09:42 AM   #2
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well you can use the --checksum option but that involves.... well... a checksum being calculated for each file. by default rsync will copy on different times and sizes, the only other thing to go on is the contents of the file itself, which would most easily be a checksum.

Actually though, maybe you want this, for a looser perspective...

Normally rsync will skip any files that are already the same length and have the same time-stamp. With
the --size-only option files will be skipped if they have the same size, regardless of timestamp. This
is useful when starting to use rsync after using another mirroring system which may not preserve
timestamps exactly.
Be very aware of the danger that you're opening yourself up to there though.

Last edited by acid_kewpie; 11-23-2012 at 09:47 AM.
Old 12-01-2012, 08:15 PM   #3
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Thanks for the reply. I created the thread because I was waiting for the rsync process to be completed. However, it seems the second round of

rsync -rltgoDv --delete --modify-window=1

is rather quick. I guess the rsync first works out checksum and decides to skip the copying the content but update only the time stamps /permission etc ?


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