apt update.-t, --target-release, --default-release
This option controls the default input to the policy engine, it creates a default pin at priority 990 using the specified
release string. This overrides the general settings in /etc/apt/preferences. Specifically pinned packages are not affected by
the value of this option. In short, this option lets you have simple control over which distribution packages will be retrieved
from. Some common examples might be -t '2.1*', -t unstable or -t sid. Configuration Item: APT::Default-Release; see also the
apt_preferences(5) manual page.