Q: How can PDF Studio be added to the Nautilus ‘open with’ list on Linux ?

A: Create a .desktop file (for example: PDFStudio2018.desktop) in /usr/share/applications (as root) with the following contents. Make sure to set the directory for the “Exec” and “Icon” lines point to the correct installation directory.

#!/usr/bin/env xdg-open
[Desktop Entry]
Name=PDF Studio 2018
Exec=/bin/sh “/opt/pdfstudio2018/pdfstudio2018” %U
Comment=Edit PDF Documents.

Then, update the desktop databases:

sudo update-mime-database /usr/share/mime
sudo update-desktop-database /usr/share/applications/    

Note: After creating this file PDF Studio can be configured as the default application when double-clicking a PDF by right-clicking a .PDF file in Nautilus, then properties/open-width/PDF Studio 2018/Set As Default.