system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do viruses know what to do despite not being alive?

How do they know to attack cells and stuff if they aren't alive? Is it by chance? Are they mechanical?
gpt
"Are they mechanical?" 

Basically. They run on pure chemistry and physics. It's not that they know what to do, but rather that that specific amalgamation of chemicals will react that way in the presence of certain things.