For a clean system.
Please expand on what you are asking. Do you mean "how can obsolete system files be deleted?"
build world does this, but I hear it isn't recommended. To elaborate, after rebuilding world, I only want the files and modules of the new world, and nothing of the world I build the new world on.Convenience targets for cleaning up the install destination directory
denoted by variable DESTDIR include:
check-old Print a list of old files and directories in the system.
delete-old Delete obsolete base system files and directories inter-
actively. When -DBATCH_DELETE_OLD_FILES is specified at
the command line, the delete operation will be non-
interactive. The variables DESTDIR, TARGET_ARCH and
TARGET should be set as with ``make installworld''.
delete-old-libs Delete obsolete base system libraries interactively.
This target should only be used if no 3rd party software
uses these libraries. When -DBATCH_DELETE_OLD_FILES is
specified at the command line, the delete operation will
be non-interactive. The variables DESTDIR, TARGET_ARCH
and TARGET should be set as with ``make installworld''.