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Looking for Software with this feature
tomos:
Dopus also does a reasonably advanced sync - and could be used as IainB suggests with xplorer2
but I dont know if sync or backup is what is required @ednja ?
MilesAhead:
"Size" could be a potentially unreliable comparison, so I would recommend using "Content" instead.
What could be useful, therefore, would be to verify whether files in the source directory with identical name/extension to files in the target directory were actually identical in content (~size), and only overwrite/copy (one way or the other) if the content were different and perhaps depending on the date. I would use a file checksum comparison between the two.
-IainB (July 03, 2015, 04:33 AM)
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I think there are likely duplicate file finders that would get rid of the unwanted sources by doing a hash if the sizes matched. I just don't know the names of any. The "keep both" case is kind of a pain. I haven't looked at dupe file utilities to see exactly what features are available.
TaoPhoenix:
I'm wondering why file size matters, because wouldn't the date be off by even a few seconds if it's two different copies of a file? Even in a high speed automated "log.txt" or something updated and then aggressively backed up, do any of the options above change context if it doesn't need to know the file size (or maybe checksum, because for ex someone opens a text file and then say MS Word adds a line break it's now different.)
IainB:
"Size" could be a potentially unreliable comparison, so I would recommend using "Content" instead.
What could be useful, therefore, would be to verify whether files in the source directory with identical name/extension to files in the target directory were actually identical in content (~size), and only overwrite/copy (one way or the other) if the content were different and perhaps depending on the date. I would use a file checksum comparison between the two.
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-IainB (July 03, 2015, 04:33 AM)
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I think there are likely duplicate file finders that would get rid of the unwanted sources by doing a hash if the sizes matched. I just don't know the names of any. The "keep both" case is kind of a pain. I haven't looked at dupe file utilities to see exactly what features are available.
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-MilesAhead (July 03, 2015, 01:00 PM)
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Yes, but I was not advocating a "keep both" policy. I can see what you mean above, but my point was purely about verification of data BEFORE the irretrievable operation of the duplicate "master" in Source being written over the same file in Target and then deleted from Source. This would be regardless of what happened to the Source master file later - e.g., if the files had identical content, then the duplicate in Target would remain untouched and the master in Source could remain untouched or simply be deleted from Source if housekeeping no longer required it to remain there.
Verification is essential:[ If the files had been identified as "identical files" in terms of filename/date/size, they still might not be identical, in fact, and so a content (checksum) comparison could verify that one way or the other.
For example, a corrupted file would give a different checksum, and if you got a different checksum in one file, then you would need to inspect both files to establish which was the uncorrupted one, and then use that as the "master".
If the presumed "identical" Source and Target files had identical content, then "moving" the Source file to the Target (per Filter #1 in the OP) would be a redundant (unnecessary) and ill-advised action, for two reasons:
* (a) efficiency, resource utilisation and workload: it would unnecessarily use computing resources (read-write) and add time to the operation for apparently no good reason whatsoever.
* (b) risk and data validation workload: if the two files have been established as being identical in content (checksum), and one is then overwritten by the other, then it would introduce the potential risk of a "bad" or corrupted write over an uncorrupted file (why would you do that?), and to avoid that would necessitate using a robust and unnecessary/inefficient (QED) write - "robust meaning "read after write" - thus using more computer resources and adding time to the process.
4wd:
I'm wondering why file size matters, because wouldn't the date be off by even a few seconds if it's two different copies of a file?-TaoPhoenix (July 03, 2015, 02:39 PM)
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Which date are you referring to?
Each file/folder has three: Created, Modified, Accessed
The Created date is the most unlikely to change so if you're just looking to match a date, name, and size, with no requirement as to contents then that is the one you'd most likely choose. However, if you're wanting to merge two backups of the same files then you'd probably go for Modified.
And as an example to your question: Sync folders by renaming files
@DyNama only wanted to match on size, date, time and extension - it all depends on the requirements.
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