osx man page for purge

purge(8)						    BSD System Manager's Manual 						  purge(8)

NAME
     purge -- force disk cache to be purged (flushed and emptied)

SYNOPSIS
     purge

DESCRIPTION
     Purge can be used to approximate initial boot conditions with a cold disk buffer cache for performance analysis. It does not affect anonymous
     memory that has been allocated through malloc, vm_allocate, etc.

SEE ALSO
     sync(8), malloc(3)

								September 20, 2005