Upgrading Using "FreeBSD Update"

[Jinsong Zhao]

Hi there,

I am going to upgrade my FreeBSD 8.2-RELEASE to 9.1-RELEASE according to 
http://www.freebsd.org/releases/9.0R/installation.html

However, I don't know how to follow the step below:

##----start here----##
# freebsd-update install

At this point, users of systems being upgraded from FreeBSD 8.2-RELEASE 
or earlier will be prompted by freebsd-update(8) to rebuild all 
third-party applications (e.g., ports installed from the ports tree) due 
to updates in system libraries.

After updating installed third-party applications (and again, only if 
freebsd-update(8) printed a message indicating that this was necessary), 
run freebsd-update(8) again so that it can delete the old (no longer 
used) system libraries:

##----end here----##

My questions is: how to rebuild all third-party applications? I have 
kept the ports tree up to date using
# portsnap fetch update
and
# portmaster -Ga
every day.

Any help will be really appreciated.

Regards,
Jinsong