> The problem with this approach is that it makes it more difficult
> for install scripts to work configuration magic.  Note how the sparc
> and hp300 install scripts have an easy time configuring network
> interfaces, hostname, etc. by simply creating the appropriate files,
> rather than having to go through a complex editing process on a file
> which won't contain any special keywords like __REPLACE_ME, or
> whatever.

Bah.  As someone who's written a NetBSD install script that has to
modify /etc/gettytab, /etc/inetd.conf, /dev/MAKEDEV, /etc/netstart,
/etc/services, /etc/ttys, and /root/.cshrc (as well as appending to
some other files and creating /etc/fstab and the network interface
configuration files, of course), I don't see this as a problem.
One way is to use an ed script with lines like:

	/hostname=/s/hostname=$hostname/

or, slightly more robust:

	/hostname=/c
	hostname=$hostname
	.

It seems poor to me to have all your configuration keyed by filename,
just to make installation scripts a tad bit easier to write.