Don’t know where else to share this, but I wrote a set of scripts for interfacing with Dropbox via the command line:
github.com/feklee/dbx-tools
dbx-tools depends on Dropbox’s own tool dbxcli.
At the moment, you can download and upload files and directories (recursively), and you can perform deletions. Newly implemented is super primitive sync™, to avoid downloading/uploading the same file twice. See the usage example in README.md.
The motivation for writing dbx-tools: I wanted to be able to conveniently interface with Dropbox from within Termux, a terminal emulator for Android.