ting FreeBSD, which discusses several
> different methods (src, binary, etc):
>
> https://docs.freebsd.org/en/books/handbook/cutting-edge/
>
> For upgrading systems from src (*not* pkgbase or freebsd-update) I use
> this as a reference:
>
> "26.6. Updating FreeBSD from Source"
> https://docs.freebsd.org/en/books/handbook/cutting-edge/#makeworld
>
> There are several examples and walk-thru, both quickstart and more
> thorough + annotated. For etcupdate in particular, there is this
> specific section:
>
> "26.6.6.1. Merging Configuration Files with etcupdate(8)"
> https://docs.freebsd.org/en/books/handbook/cutting-edge/#updating-src-completing-merge-etcupdate
>
> in general, in my experience there isn't usually a lot you need to do
> most times for etcupdate to work. I run it with every world src upgrade
> procedure as advised, so my /etc/ doesn't grow stale or drift from the
> installed binaries and such.
>
>> PS: on a machine that juste went from 14.2 to 14.3, etcuodate diff
>> shows diff, but etcupdate says
>> Failed to build new tree.
>>
>> Is it because src is not on the machine ? (not enough disk)
> That's a possibility; etcupdate is for upgrading systems from src
> (not freebsd-update binary upgrades) and it constructs its list of
> diffs and changes from /usr/src/etc/ for reference.
>
>> I soon will upgrade another machine (with /usr/src this one), and I'd
>> prefer to be sure to be able to use etcupdate on it (especially if I
>> need to to a extract or build before upgrade)
> If you're just getting started building FreeBSD from src, it's worth
> reading that whole Handbook chapter 26.6 IME.
>
> sr.
>
>
I use freebsd-update thus, I do not need /etc/update.

Except maybe for jails : I use thin jails with a shared world using 
nullfs (as in 
https://docs.freebsd.org/en/books/handbook/jails/#creating-thin-jail-nullfs 
). When updating them with freebsd-update, following 
https://docs.freebsd.org/en/books/handbook/jails/#upgrading-thin-jail I 
then update the sahred part. However /etc is not shared, thus cannot be 
updated. Should I use etcupdate then ?