Upgrading 16.04 LTS to 18.04 LTS

[Ralf Mardorf]

Other already pointed out that an upgrade from one to another LTS will
be available, if the first dot release is available for a few days. The
general idea of a LTS is to avoid over-hasty upgrades ;), however, you
could use the 'development release' option, if you dislike to wait.

sudo do-release-upgrade -d

Btw. EOL of 16.04 is April 2021, so you hopefully balance pros and cons
of staying with 16.04 or upgrading to 18.04.