bsd man page for lock

LOCK(1) 						      General Commands Manual							   LOCK(1)

NAME
       lock - reserve a terminal

SYNOPSIS
       lock [ -p ] [ -t timeout ]

DESCRIPTION
       Lock  requests a password from the user, reads it again for verification and then will normally not relinquish the terminal until the pass-
       word is repeated.  There are two other conditions under which it will terminate: it will timeout after some interval of time and it may	be
       killed  by  someone  with  the appropriate permission.  The default time limit is 15 minutes, which may be changed with the -t option where
       timeout is the time limit in minutes.  The -p option causes lock to use the user's current password instead of requesting another one.

3rd Berkeley Distribution					 February 23, 1989							   LOCK(1)