sethostid.sh

#!/bin/bash
#
# Purpose: Write the passed in parameter as hostid to /etc/hostid
#          If no parameter is passed, write current hostid to /etc/hostid
# Original Author: Fazle Arefin <fazlearefin@yahoo.com>
# http://fazlearefin.blogspot.ca/2013/03/set-hostid-etchostid-of-linux-hosts.html

# Modified by David Manouchehri <david@davidmanouchehri.com>

if [ -n "$1" ]; then
host_id=$1
  # chars must be 0-9, a-f, A-F and exactly 8 chars
  egrep -o '^[a-fA-F0-9]{8}$' <<< $host_id || exit 1

  a=${host_id:6:2}
  b=${host_id:4:2}
  c=${host_id:2:2}
  d=${host_id:0:2}
  echo -ne \\x$a\\x$b\\x$c\\x$d > /etc/hostid && echo "Success" 1>&2
else
  host_id=$(hostid)
  printf 'Usage: sethostid [hostid]\nNote: The hostid must only contain valid hex values (0-9, a-f and A-F) and be exactly 8 char long.\n'
fi

exit 0