I am asking this out of curiosity, to know what goes on 'behind the scenes' when I double click a file in a file browser, say Nautilus. Specifically, what parameters is the executable executed with? Where does the .desktop file come into play, and how does Nautilus send the filename?
This was relevant to me once when Okular would open multiple instances of the same file, and I had to write a shell script, which used to fail because the filename didn't get passed properly. (Spaces in the filenames would get converted into an HTML %20 character, and I had to figure out a lot how exactly filenames are passed.)