Running Multiple Firefox Profiles on Linux

I recently switched from Chrome to Firefox. It's so fast, and easier to trust that Mozilla has my privacy and interests at heart than Google does.

I want to run a second profile at work, to keep a distinct set of open tabs, bookmarks, and the like. Here's how I did it:

Close all Firefox windows. Run the Profile Manager with firefox -p. Create a second profile.

Open Firefox and find the directories your profiles live by browsing to about:profiles.

Substitute those directories into this firefox.desktop file, where I've marked 'XXX':

# Gnome3 .desktop file for Firefox with multiple profiles
[Desktop Entry]
Version=1.0
Name=Firefox
Comment=Browse the web
GenericName=Web Browser
Keywords=Internet;WWW;Browser;Web;Explorer
Type=Application
Exec=firefox --no-remote %u
Terminal=false
X-MultipleArgs=false
Icon=firefox
Categories=GNOME;GTK;Network;WebBrowser;
Actions=home;work
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler/chrome;video/webm;application/x-xpinstall;
StartupNotify=true

[Desktop Action home]
Name=Firefox (home)
Exec=firefox --profile .mozilla/firefox/XXX --no-remote %u

[Desktop Action work]
Name=Firefox (work)
Exec=firefox --profile .mozilla/firefox/XXX --no-remote %u

Save the above as firefox.desktop and install using:

$ desktop-file-validate firefox.desktop
$ desktop-file-install --dir=.local/share/applications firefox.desktop

This results in a Firefox icon in your applications menu that defaults to whichever profile you mark as default in the ProfileManager, but right clicking lets you select the home or work profile explicitly. Open each, and change the theme in one of them so the windows are visually distinct.

Tested on Ubuntu, RHEL 7.3, probably works on all Gnome3 desktops.