Test Whether Variable Exists

[Simon Butler]

Hi,
This should be an easy one but I cannot find the answer after hours of
searching.
I am looking for a way that I can test whether a variable exists and then
take action on the result. This is for use in a login script - not a KIX
script.
I don't want to add, change or delete the variable in anyway, just check
whether it is there or not.
Can anyone suggest a way?
Thanks,
Simon Butler.

http://www.sunbelt-software.com/ntsysadmin_list_charter.htm