external script collecting invironment variables

[vicky]

Hi all,

I'm run a "home made" script whenever I receive an accounting- start, 
stop or alive. In the script I get the value of all the attributes set 
in the environment variables (example : val = getenv("USER_NAME") ). I 
want to count how many attributes contain no value (or doesn't not 
exist) so I have a check (example : if(val == NULL) ) and I have a 
counter variable. I check with NULL because I thought when an attribute 
has no value, the value would be NULL butt apparently it is not always 
the case.

I guess it is different when the attribute is sent without a value and 
when it is not sent at all. I would like to know what value contains in 
these two cases. Anyone?

Thanks!

-- Vicky