Thank you for your response,
I had a look at www.gnu.org
and downloaded two versions of coreutils, built them and did a 'find' on '*runuser*'. Both did not have runuser. I did a google as well and found, as you did, that it should be part of the coreutils. Also, I noticed that associated with the google results was 'su' usage. Is this possibly a replacement for runuser?
In any case, thanks again, I appreciate your help,