FreeBSD Update
The freebsd-update(8) utility supports binary upgrades of i386 and amd64 systems running earlier FreeBSD releases. Systems running 7.[01234]-RELEASE, 8.[01]-RELEASE, 8.2-BETA1, or 8.2-RC[123] can upgrade as follows:
# freebsd-update upgrade -r 8.2-RELEASE
During this process, FreeBSD Update may ask the user to help by merging some configuration files or by confirming that the automatically performed merging was done correctly.
# freebsd-update install
The system must be rebooted with the newly installed kernel before continuing.
# shutdown -r now
After rebooting, freebsd-update needs to be run again to install the new userland components:
# freebsd-update install
At this point, users of systems being upgraded from FreeBSD 7.4-RELEASE or earlier will be prompted by freebsd-update 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 printed a message indicating that this was necessary), run freebsd-update again so that it can delete the old (no longer used) system libraries:
# freebsd-update install
Finally, reboot into 8.2-RELEASE:
# shutdown -r now
** taken from FreeBSD Website
