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Note to serverfault users: This closed question is answered here by four comments by hynekcer. It is then well accepted in other comments as a regularly answerable question. It's now being voted for re-opening.

When both source and destination are remote, rsync complains:

The source and destination cannot both be remote. rsync error: syntax or usage error (code 1) at main.c(1156) [Receiver=3.0.7]

Is there an insurmountable technical obstacle to making rsync do this? Or is it simply a case of not-yet-implemented? It seems relatively easy to create a local buffer in memory that mediates the transfer between two remotes, holding both hashes and data.

loopbackbee
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3 Answers3

13
scp -3r <remote src> <remote dest>

has no trouble doing this.

user1133275
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Karma Fusebox
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10

why not try and connect to the remote machine and start the transfer from there. If you are using ssh-keys you can use agent pass though to manage the authenticate for you.

ssh -A remotehostA rsync /remote/file/on/host/a remoteHostB:/destination/

This command will log you on the remoteHostA and run rsync from there.

Kaplaa
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0

You can work around this by mounting one (or both) of the remote filesystems with sshfs. Then, rsync will treat it as if it were local.

Unfortunately, this will result in a lot of bandwidth usage on the machine whose filesystem is mounted with sshfs, so I would recommend only doing this with the machine that has a lot of bandwidth between you and the third machine.

Of course, the ideal solution is for the machines to talk directly to each other. I can't think of any good reason why they should not.

Michael Hampton
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