I want to tar and send a ~700GiB directory to a remote drive I don't control. I don't have the HDD space locally to create the tarball and then copy that over. The remote is also protected by rssh - you cannot ssh into the server and run arbitrary commands.
However, I can use scp, rsync, or sftp. So, my question is specific to one of those 3 commands. Is there a way for scp, rsync, or sftp to copy a pipe, without being able to run arbitrary commands on the other side?
Update: The below solutions would not have worked for us at our secondary storage. We are restricted to running certain commands. We cannot ssh - commands that use ssh are filtered/controlled with rssh.
In the end, we canceled all our secondary accounts, and paid a lot of money to double our primary storage size (our primary host could do this without migration, which was cool). We then created a temporary archive and sent it as per normal. (Which we could not do with our initial amount of storage.)
In the future, we will be using a secondary VPS with its own dedicated larger storage, so that this does not occur again. It's clear that what I was asking for is not possible.