I usually close Firefox with the command:
killall firefox
Many websites and tabs accumulate over time. At the end of the day, many remain unprocessed and should not be processed the next day either.
So I want to close Firefox and start it again as empty as possible, but Firefox restores all tabs.
How could I prevent this?
Update
Using firefox 99.0
Killall firefox will force firefox to restore its tabs, no matter what your settings are. Most convenient way is to open Settings->General and untick "Open previous windows and tabs":
If you want to prevent event the restore on a crash (which you are doing by "kill") you could setup in about:config
browser.sessionstore.resume_session_once True
In case it is not there, you could add it by entering it into about:config, select "boolean" ,then pressing the "+" button
The tab recovery data is stored in the sessionstore-backups directory under your profile directory (example ~/.mozilla/firefox/..XYZ..x.default-release/sessionstore-backups/ ) . If you delete (or move to a different location in case you change your mind or something breaks) all the files in this directory there will be nothing to restore. You can for example make a wrapper script to clean-invoke firefox that wipes this directory first.
Go to Settings > General > Startup and then uncheck the option "Open previous windows and tabs"
