apt-get has a
-y, --yes, --assume-yes switch:
Automatic yes to prompts; assume "yes" as answer to all prompts and
run non-interactively. If an undesirable situation, such as
changing a held package, trying to install a unauthenticated
package or removing an essential package occurs then apt-get will
abort. Configuration Item: APT::Get::Assume-Yes.
or, in alternative a
Force yes; this is a dangerous option that will cause apt to
continue without prompting if it is doing something potentially
harmful. It should not be used except in very special situations.
Using force-yes can potentially destroy your system! Configuration