How to Install firefox 12 in ubuntu linux

A. Install Firefox 12 in 5 easy steps

1. Download

Download the release from the official channels page:
www.mozilla.com/firefox/channels/
A 64 bit build is also available in the x86_64 directory of Mozilla's FTP.

This how-to supposes that the downloaded file is saved in the "Downloads" directory situated in your home directory.

2. Extract

The downloaded file is a compressed .tar.bz2 archive. In case you want to Learn more on these extensions: tar, bzip2. To extract this juicy archive, open the Downloads directory. Look for a file named firefox-12.0.tar.bz2, right-click on it and select "extract here".

Alternatively, you can extract the archive from the command line:
cd ~/Downloads/
tar xjf firefox-12.0.tar.bz2

For those interested, here are the tar arguments used in the command:
x : eXtract
j : deal with bzipped file
f : read from a file (rather than a tape device)

The firefox-12.0.tar.bz2 archive can now be deleted.

3. Move to /opt

External programs like LibreOffice, Google Chrome, Adobe reader, ... are all installed in the /opt directory. If you want more info about why /opt, check out these two links:
Where to install my products on linux?
Filesystem Hierarchy Standard

If you already had a previous Firefox version installed in the /opt directory, remove it with the following command:
sudo rm -r /opt/firefox

Now move the firefox directory (which was created in your Downloads folder during extraction) to /opt:
sudo mv firefox /opt/firefox12

4. Set up symbolic links

Depending on you usage pattern, follow the instructions for case 1 OR for case 2.

Case 1: you want to use Firefox 12 as you default browser:

"Backup" the old Firefox launcher: sudo mv /usr/bin/firefox /usr/bin/firefox-old Create a symbolic link pointing to the new Firefox version: sudo ln -s /opt/firefox12/firefox /usr/bin/firefox No need to update your icons/shortcuts, they should now launch the new version of Firefox. Your old Firefox version is still installed. If you want to use it, run firefox-old in a terminal or create shortcuts/icons referring to firefox-old.

Case 2: you want to keep using your "old" Firefox by default:

Create a symbolic link pointing to the new Firefox version: sudo ln -s /opt/firefox12/firefox /usr/bin/firefox12 Launch the newly installed Firefox by running firefox12 in a terminal, or create shortcuts/icons referring to firefox12.

5. Updates & Final

Firefox 12 will manage its own updates independently of your system's package manager, an download subsequent releases. There will be no need to repeat the whole "procedure"... Enjoy Firefox 12!