4.5 to 4.6

update ports is easy and upgrade each package via ports is also easy. but I am still not clear about how to upgrade from one version to another? Is it safe?

Go read Ch.19 of the handbook.

>> Is it safe?

Unlike binary upgrade in Linux which is somewhat unsafe and unreliable, in *BSDs it's relatively safe to upgrade from one version to another via so-called buildworld because of its flexibility.

If you don't have enough gut to give buildworld a try, then you don't qualify to use BSDs.

assuming you have cvsup'd the source and are in as root:

1) go into the src directory ...
% cd /usr/src

2) build the new componants (does not install)
% make buildworld

3) build new kernel (assuming GENERIC)
%cd sys/i386/ conf
%config GENERIC
%cd ../compile/GENERIC
%make depend
%make
%make install

4) reboot into single user mode
%reboot

5) on reboot, hit something OTHER than ENTER to get to the boot prompt.
> boot -s

6) choose shell (just hit ENTER)

7) make filesystem writeable
#mount -u /

8) run installworld
#make installworld

9) run mergemaster -- I do it with the -a flag so it doesn't try to diff the settings files
#mergemaster -a

10) reboot
#reboot

If you are doing this remotely, there is no way to do it in singal user mode. Boot normally and re-connect. I did this, for example, with a webserver, so I shutdown httpd and mysqld before running installworld.

Hope this helps.

Brett