support hostname env var override

arch.sh

@@ -31,7 +31,7 @@ locale-gen
 echo "LANG=en_US.UTF-8" > /etc/locale.conf
 
 # setup hostname
-echo "arch" > /etc/hostname
+echo "${hostname:-arch}" > /etc/hostname
 echo "127.0.0.1 localhost" > /etc/hosts
 echo "::1 localhost" >> /etc/hosts
 echo "127.0.1.1 $(cat /etc/hostname).localdomain $(cat /etc/hostname)" >> /etc/hosts