If you use Firefox for web development and also for regular browsing you would sooner or later realize that the Firefox addons that you use for web development is slowing down your browser and you would want to use a Firefox profile without any addons for your regular browsing. But if you do that and you want to use your developer tools once in a while you will usually have to close your Firefox session before you start a new session loading your development profile. Well not really. Here is how you can use two Firefox profiles simultaneously and not having to go through the command line every time.
These instructions apply for Ubuntu but should probably work for other other GNU / Linux variants as well.
You can start a new firefox session with a new profile by using the following command
firefox --profile-manager -no-remote
Now the next part is to add this as an option to the firefox icon that appears in your dashboard. For this the easy option is to edit /usr/share/applications/firefox.desktop. You can alternatively create a copy of the desktop file into your local users ~/.local/share/applications folder.
Find the line "Actions=" under the [Desktop] section in the file and prefix "NewProfile;" to the value of the string.
Then add a new section
[Desktop Action NewProfile]
Name=Open a New Profile
Exec=firefox --profile-manager -no-remote
below the [Desktop] section. That is it. Now you should see a new option "Open a New Profile" when you right click on the firefox icon in your dashboard.