I'm not quite sure what the issue is. I'm on Kali Linux 2.0 right now, fresh install. The following worked on Ubuntu 14.04 but it's not working anymore (maybe I accidentally changed it?). It looks correct to me, but every time it runs it blocks.
backup_folder=$(ssh -i /home/dexter/.ssh/id_rsa $server 'ls -t '$dir' | head -1')
This is part of a larger script. $server and $dir are set. When I run the command alone, I get the correct output, but it doesn't end the connection.