[ale] Bash: How to determine if called from cron?

[Christopher Bergeron]

Does anyone know of an easy way for my script to determine if it's being 
run from cron or from a user shell? 

I have a feeling theres an easy way to do this, but I'm drawing a 
complete blank right now.  I'm looking at my Environment vars, but I'm 
not sure what gets set by Cron when it runs a script.

Any ideas are much appreciated...

Kind regards,
CB