Ubuntu Linux OS is free and comes with many free applications. Mozilla Firefox is among many. Since Mozilla Firefox team comes up with their latest browser version every six weeks, so it is must to update to latest version. However there is no auto update option available to install newer version for Ubuntu and requires manual update.
There is an easy way to update using command prompt. First download the new version and save it in the directory Place>Home Folder. Then go to Applications>Accessories>Terminal and paste the following commandif [[ ! -f /usr/bin/firefox ]]; then sudo apt-get update && sudo apt-get install firefox; fi && if [[ -e ~/.mozilla ]]; then cp -R ~/.mozilla ~/.mozilla.backup; fi && sudo tar -jxvf firefox-3*.tar.bz2 -C /opt && rm firefox-3*.tar.bz2 && sudo mv /opt/firefox/plugins /opt/firefox/plugins.backup && sudo ln -s /usr/lib/xulrunner-addons/plugins /opt/firefox/plugins && sudo dpkg-divert --divert /usr/bin/firefox.ubuntu --rename /usr/bin/firefox && sudo ln -s /opt/firefox/firefox /usr/bin/firefox
Give password if required and restart Firefox.
If you want to Uninstall any version of Firefox then follow command as below
sudo rm /usr/bin/firefox && sudo dpkg-divert --rename --remove /usr/bin/firefox && sudo rm -r /opt/firefox