Chris> umm, the daemons should go in /usr/local/libexec, if they're invoked
Chris> by other programs (e.g. inetd), or /usr/local/sbin, if they're invoked
Chris> from rc.

> This is a narrow distinction that I don't completely grasp yet--whether
> something belongs in /usr/libexec or in /usr/sbin.

Think of /usr/libexec as if it is named /demon/sbin :-)

> Things like the fax queue daemon (faxq) is only normally going to be
> started up once by /etc/rc (which is effectively a program for the
> "executed by another program" metric).  What's the key difference that
> makes it eligible for an sbin directory ?

I think /etc/rc is a special case; it is not really a demon.
I occasionally restart by hand demons started from /etc/rc.

Another way to look at this: programs started by demons
may assume a) existence of such a demon and b) use some
peculiar conventions shared between the demon and the
support program.  Restarting such programs by hand
violates a) and may violate b).  So things you *never*
want to start by hand should not go in sbin.

> Do config files belong under /var/spool/<something>/etc or should they
> be in /var/<something>/etc (and put true "spool-like things" in
> /var/<something>/spool or /var/spool/<something>)?

May be understanding the rationale will help. /var and
/var/spool have the heaviest traffic on most all machines.
If they are on a separate disk, you are more likely to lose
files in or even entire /var or /var/spool than any other
dir. tree.  Your machine should not lose much functionality
and certainly not grind to a halt in case files in
/var/spool are lost.

Can you continue faxing if you lose these config files?

Of couse, on a machine with only one or two disks you are
not likely to put /var or /var/spool on a separate disk
(putting it on another partition on the same disk is a good
way to slow your system down!).  So such arrangement does not
really matter for small machines but for large machines what
hier(7) says makes a lot of sense.  But as it typical in the
Unix world a lot of things are left unsaid!

--bakul