man yes
outputs


YES(1)                    BSD General Commands Manual                   YES(1)

NAME
     yes -- be repetitively affirmative

SYNOPSIS
     yes [expletive]

DESCRIPTION
     yes outputs expletive, or, by default, ``y'', forever.

HISTORY
     The yes command appeared in 4.0BSD.

4th Berkeley Distribution        June 6, 1993        4th Berkeley Distribution