P(1) General Commands Manual P(1)

p - paginate

p [ -number ] [ file ... ]

P copies its standard input, or the named files if given, to its standard output, stopping at the end of every page, to wait for a newline from the user. The option sets the number of lines on a page (default: 22).

While waiting for a newline, p interprets the commands:

!
Pass the rest of the line to the shell as a command.
Quit.

/appl/cmd/p.b