#!/bin/bash

which dmidecode >/dev/null
if [ $? -ne 0 ]; then
 echo dmidecode not found
 exit 1
fi

serial=`dmidecode | grep -im1 'serial number' | cut -d' ' -f3 | tr -d [:space:]`
if [ ${#serial} -eq 0 ]; then
 echo no serial found
 exit 1
fi
echo $serial