Ubuntu Upgrade

1. 버전확인

$ uname -mrs
$ lsb_release -a

Ubuntu Servers (Recommended)

1. If you installed from 14.04 or 12.04 originally you will need to remove LTS upgrade restrictions. Replace Prompt=lts with Prompt=normal: 

   sudo pico /etc/update-manager/release-upgrades

2. Install update-manager-core if it is not already installed:

   sudo apt-get install update-manager-core

3. Launch the upgrade tool:

   do-release-upgrade

4. Follow the on-screen instructions.