MacOS – How to keep Safari from re-opening the tabs from the last session

You can use this block of AppleScript to loop through your tabs on a window:

tell application "Safari"
    repeat
        repeat with i from (count of tabs of window 1) to 1 by -1
            set thisTab to tab i of window 1
            set current tab of window 1 to thisTab
            delay 1
        end repeat
    end repeat
end tell

This will go through all your tabs and switch every 1 second. Just change the delay to change the time before each tab switches.

The setting was called "Confirm before closing multiple tabs or windows", but it was removed in 10.7 when Resume was introduced. defaults write com.apple.Safari ConfirmClosingMultiplePages -bool true doesn't work anymore either.

The part of Resume where application state is kept after quitting was disabled by default in 10.8, but you can reenable it from the General preference pane:

You can also enable it in just Safari by running defaults write com.apple.Safari NSQuitAlwaysKeepsWindows -bool true and quitting and reopening Safari.

Safari will still reload tabs when they are restored. And restoring state has only worked about half of the time for me since Safari 6 or 10.8.

You might also change the shortcut for quitting Safari:

Or disable some of the shortcuts completely:

defaults write com.apple.Safari NSUserKeyEquivalents -dict 'Quit Safari' '\0' 'Close Window' '\0' 'Close All Windows' '\0'