In file explorer (Nautilus) under Ubuntu, I can select a file and right click and scroll to:
open with other application
My question is how can I add emacs to that list of "other application"
After we had installed emacs we may not yet have a .desktop file to integrate it with the desktop environment.
We then can copy the emacs23.desktop file if located in /usr/share/applications or we can create a custom emacs.desktop file in ~.local/share/applications, e.g. with the following content (add further options at your needs).
[Desktop Entry]
Name=Emacs 23
Comment=
Exec=/usr/bin/emacs23 %F
Icon=
Terminal=true
Type=Application
We can then select Emacs in the list of "Open With Other Applications -> Show other applications" on right click of a file with a content we want to associate Emacs with.
After having selected the now present Emacs (note that there is no icon defined yet if using a custom dektop file, give the path to an icon in your emacs.desktop above) we can then choose to "Open with Emacs" in the Nautilus context menu:
To undo this we simply right click on the Emacs entry in the menu that pops up after having selected "Open With Other Application..." and say "Forget association":
(Forget association option does not exist for Ubuntu 16.04 and later)
