From the command "man apt-get"

Quote------
-y, --yes, --assume-yes 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 or removing an essential package, occurs then
apt-get will abort. Configuration Item: APT::Get::Assume-Yes.
-----end-quote

I'm on mobile so got the man page off the net. Looks right though. Your
commands would then be like :

apt-get -y install synaptic

And so on then you should be good to go.