#!/bin/sh
#
# try several ways to guess the hostname

(

# this is what Debian uses
cat /etc/mailname

# this is often the short hostname
cat /etc/hostname

# this file was mentioned on the Internet
cat /etc/HOSTNAME

# probably a good value on GNU/Linux
hostname -f

# often the short hostname, but widely available
hostname

) 2>/dev/null | sort -u