This article requires more details with links to the other upgrade options. Maybe even have a general intro page on updates. Also, the same steps to record the Ubuntu version information before running the update.
In a server environment there are different levels of updates,
- upgrade - Package Update without removing packages
- dist-upgrade - Package Update using conflict resolution to remove outdated packages
- do-release-update - Release Updates
This is to allow the administer fine grained control. The more higher level of updates, the more risk to a system.
upgrade
Package Update using upgrade is the safest and covered in Setup Ubuntu Linux Base Server. The command to upgrade is,
sudo apt-get upgrade
A reboot is almost never required.
From the man pages,
dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. So, dist-upgrade command may remove some packages. The /etc/apt/sources.list file contains a list of locations from which to retrieve desired package files. See also apt_preferences(5) for a mechanism for overriding the general settings for individual packages.
dist-upgrade
The next level is,
sudo apt-get dist-upgrade
This type of upgrade often updates the Linux headers. A reboot is sometimes required.
From the man pages,
dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. So, dist-upgrade command may remove some packages. The /etc/apt/sources.list file contains a list of locations from which to retrieve desired package files. See also apt_preferences(5) for a mechanism for overriding the general settings for individual packages.
do-release-update
Release updates are the most disruptive. The almost always require a reboot. The process is quite involved and it is recommended to turn off all services.