User Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/37.0.2062.120 Chrome/37.0.2062.120 Safari/537.36 Steps to reproduce: Close Firefox gracefully by sending it a SIGTERM signal. I also tried to send Firefox other messages to make it close gracefully: SIGQUIT, SIGINT, SIGUSR1, SIGPWR. Actual results: If I send SIGTERM or SIGPWR it kills itself and when I start it again it says "This is embarrassing..." (didn't close gracefully) If I send SIGQUIT/SIGINT they are ignored in most cases (depends how I run firefox, from a desktop shortcut, from the terminal, in the background in a terminal etc) SIGUSR1 causes FF 33.0 (latest) to close gracefully on my Ubuntu PC. SIGUSR1 causes Iceweasel 31.2.0 (latest) to kill itself on my Debian PC. Expected results: FF should close gracefully when it receives SIGTERM. FF should not ignore SIGQUIT, it should close gracefully. Correct responses to the other signals mentioned are debatable. But the above two need to be corrected. I also found this similar bug report, but it only mentions SIGTERM https://bugzilla.mozilla.org/show_bug.cgi?id=336193

Bug 336193 has plenty of discussion about SIGQUIT as well; I don't think it's useful to have a second report on essentially the same issue, so I'm going to mark this as a duplicate. Feel free to state your case(s) there and try and revive the bug.