lock -- Lock an opened file against changelist submission
p4 lock [ -c changelist# ] [ file ... ]
The open files named are locked in the depot, preventing any
user other than the current user on the current client from
submitting changes to the files. If a file is already locked
then the lock request is rejected. If no file names are given
then lock all files currently open in the changelist number given
or in the 'default' changelist if no changelist number is given.