If you’re involved with developing on Mozilla, odds are you’ve got at least one or two (dozen? :) profiles for testing. Some used regularly, some created-and-forgotten for one-off testing, some you’ve forgotten what they’re for. And you probably jump through gymnastics with the Profile Manager to create, select, and delete said profiles.
Once upon a time I used to do the same thing, until someone pointed out that there’s a different way to create and select profiles.
Old And Busted:
1) run firefox -P
2) Create new profile
3) Click, click, typeity, click
4) Select new profile
5) Swear, run firefox -P again because you didn’t mean to set that as your default
6) What was I doing again?
7) Oh yeah, test that thing. Quit.
8) run firefox -P
9) Delete profile
10) Lather, rinse, repeat for repeating testing with a clean new profile.
1) mkdir /tmp/blah (or ~/profiles/blah for more permanence)
2) firefox -profile /tmp/blah
3) rm -rf /tmp/blah
At least for my workflow, I haven’t used the Profile Manager since. (This trick doesn’t depend on Profile Manager at all, so even it was removed at some point this would still work.) Some folks might prefer the Profile Manger for their needs, but this works great for me.