How to transfer files from a bluetooth-connected device using the command line (with middle-level commands)

### Situation I am working with Ubuntu 16.04 and 18.04. After extensive research for another [post on AskUbuntu](https://askubuntu.com/q/1222672) I am looking for alternatives to the pair BlueZ/Blueman for transferring files via Bluetooth. This is because these pieces of software, beside not working for me on the spot, have been developing towards the removal of **file browsing** capabilities. Thanks to that I could use my file manager or a terminal to look into and work with the content of my mobile. See "Drop browse feature" in their [changelog for version 2.1 onwards](https://askubuntu.com/q/1222672/446253) , for example. If I understand this correctly, would I want to transfer any number of pictures from my Bluetooth-connected mobile into a computer, I ought to send them in batches from the mobile, as suggested from example [in this other post](https://askubuntu.com/a/1157025) . This is unhandy. ### Questions "Middle levels", as in the title, are those sorts of commands invoked under the hood by Bluez, Blueman and suchlike, so one level of refinement below their own. I am glad to learn this. Eventually I might use a script. Therefore, I would ask some guidance, say a 'canonical answer', on using the command line (bash) 1. to establish a Bluetooth connection between a computer and an external device; 2. to make the content of the remote device browsable (á la ls) from the receiving computer; assuming all necessary hardware is up and running. ### Note I do rule out the assistance of helping programs like Bluez etc. If there are working self-contained alternatives to Bluez/Blueman, I am glad to hear of them. However, the wish is to have a canonical answer with a long breath, overcoming the limitation of several outdated answers on SE.