The `yes` command floods stdout with a whole bunch of y's.
If you don't want to to say y, then give the yes command a parameter, maybe n is what you want . . .
`yes n` will print a crap load of n's to the screen. Okay, so how is this useful? Well, just pipe it to that command that you want to keep on tell yes to, or no to.
Yes, the command for when yes really means yes
working example
yes | cp -R * /backup