#!/bin/sh

###
#
#            Name:  shard.sh
#     Description:  This Casper extension attribute takes a Mac serial
#                   number as input and uses that serial number to output a
#                   number from 1 to 10. This can be useful in scoping Casper
#                   policies to a specific percentage of the fleet.
#          Author:  Elliot Jordan <elliot@lindegroup.com>
#         Created:  2015-05-15
#   Last Modified:  2015-05-15
#         Version:  1.0
#
###

SERIAL=$(ioreg -c IOPlatformExpertDevice -d 2 |awk '/IOPlatformSerialNumber/ {print $3}' |sed s/\"//g)
HEX=$(echo "$SERIAL" | md5 | colrm 1 28) # last four hex digits of the serial's md5
DEC=$(( 16#$HEX )) # number between 0 and 65535
SHARD=$(( DEC % 10 )) # number between 0 and 9

echo "<result>$SHARD</result>"

exit 0