Firefox profiles on Ubuntu
Running multiple simultaneous Firefox profiles is broken on Ubuntu. It works fine on Debian and Gentoo, among others. I don't know if the Ubuntu maintainer is refusing to fix it on the basis that it's an upstream problem, or if they just haven't looked at what the other distros are doing...
Anyway, it's pretty easy to fix with a /usr/local/bin/firefox wrapper:
#!/bin/bash [[ " $*" == *" -P"* ]] && export MOZ_NO_REMOTE=1 exec /usr/bin/firefox "$@"
This prevents the binary from attempting to contact the running instance, which allows the -P and -ProfileManager options to work.