What is a Linux signal, and what are some common ones you work with?

As a prospective Google site reliability engineer, you are expected to have a working knowledge of some of the more common operating systems. One of these is Linux. While you don't need to be proficient in writing Linux code, you should be familiar with some key commands. If you're asked about a command that you're not familiar with, readily admit this, and then describe how you would go about obtaining the information.