How do I install latest Firefox version 4.0 in Linux operating systems?
You can easily install Firefox version 4.0 in Linux and the best part is you won't lose any of your bookmarks or browsing history created by Firefox 3.x. However, some of your extensions and other add-ons might not work until updates for them are made available. I strongly recommend that you backup existing your $HOME/.mozilla/ directory. Open a command-line terminal (select Applications > Accessories > Terminal), and then type the following commands:
Step #1: Backup ~/.mozilla/ Directory
Type the following command:
$ mkdir ~/backups
$ cp -avr ~/.mozilla/ ~/backups
Step #2: Download Firefox v4.x
Visit the official site and save firefox-4.0.tar.bz2 in /tmp directory.
Step #3: Install Firefox v4.x in /opt
Type the following command as the root user, enter:
$ cd /tmp
$ sudo tar -jxvf firefox-4.0.tar.bz2 -C /opt/
Or you can switch to the root user by typing su - and entering the root password, when prompted:
$ su -
# cd /tmp
# tar -jxvf firefox-4.0.tar.bz2 -C /opt/
How Do I Start Firefox v4.0?
To start the Firefox version 4.x, type (please shutdown running Firefox v3.x):
$ /opt/firefox/firefox &