Set RPI hostname based on /boot/serial_hostname.txt file

gistfile1.txt

#! /bin/sh
### BEGIN INIT INFO
# Provides:          serial_hostname
# Required-Start:    $local_fs
# Required-Stop:
# X-Start-Before     hostname
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Set hostname based on /boot/serial_hostname.txt
# Description:       Read the machines hostname from /boot/serial_hostname.txt,
#                    based on machine serial number
### END INIT INFO

. /lib/lsb/init-functions

log_daemon_msg "Starting serial_hostname"

if [ -f /boot/serial_hostname.txt ]
  then
    SERIAL=`cat /proc/cpuinfo | grep Serial | awk '{ print $3 }'`
    NEWHOST=`grep $SERIAL /boot/serial_hostname.txt | awk '{ print $2 }'`
    if [ -z "$NEWHOST" ]; then
        sed -i "$ a${SERIAL} ${SERIAL}" /boot/serial_hostname.txt
        NEWHOST=$SERIAL
    fi
    if [ ! -z "$NEWHOST" ]; then
       OLDHOST=`cat /etc/hostname`
       log_daemon_msg "Changing $OLDHOST to $NEWHOST..."
       echo $NEWHOST > /etc/hostname
       sed -i "s/127.0.1.1.*/127.0.1.1\t$NEWHOST/g" /etc/hosts
    fi
  fi
log_daemon_msg "serial_hostname complete"
exit 0

Original is a completed script from simplesi on the raspberry-pi forum. Format for serial_hostname.txt is:

000000004ca???00 Raspi01 Web
000000005ac???a1 Raspi02 Dev
0000000083b7???8 Raspi03 TV

Only the 2nd field is used (The 3rd is for a simple desc of the purpose of the RPi).

Moved log_daemon_msg complete message outside of if statements.