https and ftp are examples of scheme. one can create custom schemes.
resources
- https://specifications.freedesktop.org/desktop-entry-spec/latest/exec-variables.html
- https://github.com/youssefaltai/linux-custom-url-scheme
- https://unix.stackexchange.com/questions/497146/create-a-custom-url-protocol-handler
- https://unix.stackexchange.com/questions/9152/how-to-open-a-file-in-an-existing-emacs-process-from-command-line