options:
-h, --help show this help message and exit
-c, --check-dist-upgrades Check if a new distribution release is available
-d, --devel-release Check if upgrading to the latest devel release is possible
--dist-upgrade, --dist-ugprade Try to run a dist-upgrade
And sure enough, update-manager's help shows:
update-manager --help
usage: update-manager [options]
options: dist-upgrades
Check if a new distribution release is available
possible
Try to run a dist-upgrade
-h, --help show this help message and exit
-c, --check-
-d, --devel-release Check if upgrading to the latest devel release is
--dist-upgrade, --dist-ugprade
...which is exactly what you were using. :)