Add Utopic main repository
sudo add-apt-repository "deb http://archive.ubuntu.com/ubuntu utopic main"
Update package lists
sudo apt-get update
Update kernel meta package to install last version
sudo apt-get install linux-generic
Remove repository, to avoid any harmful update of other packages
sudo add-apt-repository -r "deb http://archive.ubuntu.com/ubuntu utopic main"
Update package lists
sudo apt-get update
Tested on:
~$ uname -a
Linux machine 3.16.0-23-generic #31-Ubuntu SMP Tue Oct 21 17:56:17 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
~$ lsb_release -rc
Release: 14.04
Codename: trusty
Note:
To update kernel follow same steps, only use update repository instead:
"deb http://archive.ubuntu.com/ubuntu utopic-updates main"
In case you want only security updates, use:
"deb http://archive.ubuntu.com/ubuntu utopic-security main"