APT HOWTO - Managing packages

APT HOWTO - Managing packages

3.5 Upgrading to a new release

This feature of APT allows you to upgrade an entire Debian system at once, either through the Internet or from a new CD (purchased or downloaded as an ISO image).

It is also used when changes are made to the relationships between installed packages. With apt-get upgrade, these packages would be kept untouched (kept back).

For example, suppose that you're using revision 0 of the stable version of Debian and you buy a CD with revision 3. You can use APT to upgrade your system from this new CD. To do this, use apt-cdrom (see section Adding a CD-ROM to the sources.list file, Section 2.4) to add the CD to your /etc/apt/sources.list and run apt-get dist-upgrade.

It's important to note that APT always looks for the most recent versions of packages. Therefore, if your /etc/apt/sources.list were to list an archive that had a more recent version of a package than the version on the CD, APT would download the package from there.

In the example shown in section Upgrading packages, Section 3.4, we saw that some packages were kept back. We'll solve this problem now with the dist-upgrade method:

# apt-get -u dist-upgrade
Reading Package Lists... Done