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I have gotten pretty used to the -c option with rsync which will compare the checksum of the files to see if there are changes instead of relying on times. Unfortunately there are a couple projects i work on where i cant use rsync because there is no SSH access to the server and must use FTP.

Is there a Mac or *nix client (that i can compile of OS X) that supports this kind of synchronization option? And bonus points if it will take an rsync style exclude file for things that shouldnt be touched.

I have tried mounting ftpfs with FUSE as well as ExpanDrive, but they are just dead slow (some times a dry run of a fairly modest project can take 30 minutes).

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up vote 1 down vote accepted

The FTP protocol is not flexible enough to do this (see this previous question). You'd need some way to have the server calculate the file's checksum and send it to the client, so the client can decide whether or not to transfer the file; and FTP doesn't have any feature like this.

If you try to do it with something like ftpfs, what'll wind up happening is that the client will download the entire file, calculate its checksum, and use that to decide whether or not to transfer the file ... again.

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Im not necessarily concerned with the fact of double downloads, more with if the files are different between source/target then only overwrite those files. As i noted I have tried ftpfs+rsync but its unbearably slow. I suppose that is because of the double download and checksum time but it seems like it should be faster... – prodigitalson Feb 22 '13 at 2:53
I'm not sure how efficient ftpfs is; it might be a bit faster to write a script to FTP down the entire directory, then use rsync -c --dry-run to figure out which files need to be updated, then FTP just those back up... – Gordon Davisson Feb 22 '13 at 6:01
Yeah, that sounds like the best option im going to get at this point. – prodigitalson Feb 22 '13 at 16:38

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