I have Ubuntu 12.04 LTS version. Now I want to upgrade to 14.04 LTS. Can I directly upgrade to 14.04, or I have to update first to 13.04 & then 14.04?
I would recommend that you take a backup of your data and do a fresh install instead.
However, if you wish to upgrade, enter the following commands in the terminal
sudo apt-get update
sudo apt-get upgrade
sudo update-manager -d
Now your Update Manager will open and it will show the availability of the upgrade. Click on the
Yes, you can directly upgrade.
You can always upgrade from one release to the immediate next release. In addition to this you can always upgrade from one LTS release to the next LTS release.
Upgrade in the normal way, either through the GUI through
do-release-upgrade in the console (you don't need
sudo in front of that command).