Rob gives us this:

On Solaris I'm using this instead. It already provides a program that REALLY
jumps through hoops to get the hostname (checks NIS, DNS, local files, etc), so
I'm going to use that instead. I use it in my script like this:

/usr/lib/mail/sh/check-hostname | awk 'BEGIN { FS=" " } { if ($3 == "OK:") {
print $7 } }'

We should use this for any setup type code that needs the FQDN or hostname.