I suspect most people don't even know firefox has a ProfileManager, but I'm here to warn you not to use it. It just cost me years of bookmarks and saved passwords.
For testing purposes I invoked firefox-bin with the -ProfileManager flag (don't do this, it's broken!) and created a fresh firefox profile with the name "temp" as I've been doing for years. I ran the "temp" profile while doing my testing, quit firefox and then re-invoked firefox with the -ProfileManager flag and used it to delete the "temp" profile because I didn't need it any more. Unfortunately, deleting "temp" also deleted the "default" profile I've been using for years, which had all of my bookmarks and saved passwords and maybe other stuff I haven't even thought about yet. I'm copying an old firefox profile from another machine that's four years out of date. Maybe I can rescue an ort here or there. What a fscking disaster. Lesson learned: if you need to start firefox with a fresh profile, just move your ~/.mozilla directory out of the way and let firefox create a new one from scratch.
