One can upload a file to their Dropbox via a cURL post, provided they have created an app and have an access token, which just takes a few minutes to set up.

curl -X POST https://content.dropboxapi.com/2/files/upload --header "Authorization: Bearer ACCESSTOKEN" --header "Dropbox-API-Arg: {\"path\": \"/DROPBOXFILEPATH/DROPBOXFILENAME\"}" --header "Content-Type: application/octet-stream" --data-binary @/LOCALFILEPATH/LOCALFILENAME