I use the private mode of firefox quite often, for example when I want to test an application while being authenticated in one windown and not authenticated in another window.
I also use this mode when I want to browse some commercial websites that I know do a lot of tracking (hey there amazon!).
Finally, my firefox always have few windows and a bunch of tabs open and when traveling quite often I want to open firefox quickly to check something but I do not want to have it coming with all its windows and tabs.
Until now, I used either different browser or midori that allows starting it directly in private mode in these situations.
So this morning I took myself by the hand and looked closer at fixing my system for my use-case:
The recipe turned out to be pretty simple:
1/ Get the firefox.desktop file:
cp /usr/share/applications/firefox.desktop ~/firefox-private.desktop
2/ Adjust it as follow:
-Name=Firefox +Name=Firefox (private browsing) [...] -Exec=firefox %u +Exec=firefox -private-window %u
3/ Install the new desktop file:
3.1/ In /usr/share/applications/ for every users on the system
sudo cp ~/firefox-private.desktop /usr/share/applications/
or
3.2/ In ~/.local/share/applications/ for your user only
sudo cp /.local/share/applications/
With this trick, you can now start firefox in private browsing mode directly from the menu.