What is the meaning of "-y" in this command

Question

I don't understand the meaning of -y.

command:

apt-get install -y clickhouse-client & sudo apt-get install -y passenger

There are many commands have -y.

Answer 1

The -y means Assume yes as answer

i.e. in any case of a question, the program will automatically respond with yes as answer.

From man apt-get

-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.