This question from 2013 Can I do a Silent or Unattended Release Upgrade?
explains how to upgrades to the new stable release without prompts:
$ do-release-upgrade -f DistUpgradeViewNonInteractive
However this does not work on my system:
$ do-release-upgrade
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [198 B]
Get:2 Upgrade tool [1'261 kB]
Fetched 1'261 kB in 0s (0 B/s)
authenticate 'yakkety.tar.gz' against 'yakkety.tar.gz.gpg'
extracting 'yakkety.tar.gz'
Reading cache
Checking package manager
Reading package lists... Done
Building dependency tree
Reading state information... Done
Get:1 http://ch.archive.ubuntu.com/ubuntu yakkety InRelease [247 kB]
...
However, $ do-release-upgrade -f DistUpgradeViewNonInteractive
Checking for a new Ubuntu release
Get:1 Upgrade tool signature [198 B]
Get:2 Upgrade tool [1'261 kB]
Fetched 1'261 kB in 0s (0 B/s)
authenticate 'yakkety.tar.gz' against 'yakkety.tar.gz.gpg'
extracting 'yakkety.tar.gz'
and gets stuck here. It does not continue with the "Reading cache".
How to make an unattended release Upgrade from Ubuntu Ubuntu 16.04.1 LTS?
