MEGA is a cloud storage provider that can be used to store files and sync them across multiple devices. MEGA has a fully featured commandline client and daemon for Linux distributions, including Raspbian.
Raspbian client can be downloaded here.
Install packages required by the MEGA client:
$ sudo apt install libc-ares2 libcrypto++6
$ sudo dpkg -i megacmd-Raspbian_9.0_armhf.deb
$ mega-login login your-login your-password
$ mega-ls /
$ mega-exec sync /path/on/local/system /path/on/mega
This passes the command to the mega service running in the background and you get your shell back. Paths on your MEGA drive begin with
/ as the root directory.