To synchronize two directories on two or more computers, rsync can be a useful solution. This is a reference^[1]:

rsync -a username@remote_host:/home/username/dir1 place_to_sync_on_local_machine

Running rsync in the background

An article showing how to run rsync in the background can be found here:^[2]. The instruction to run it in the background can be found here:

nohup rsync -a host.origin:/path/data destiny.host:/path/ &

Run rsync with ssh

To supply an ssh-key file to rsync, one can use the following command:

rsync -avzhe "ssh -i ~/.ssh/KEYFILE_NAME.pem"  <user>@<remote-machine_DNS>:<remote folder> <local folder> --progress