how to determine if a shell is running as Administrator?

Thu Feb 5 09:44:00 GMT 2015

What's a reliable and efficient way to determine programmatically if the shell
that's running has elevated privileges?
Or if you prefer, how can I tell if the shell was started with "Run as
administrator"?
I'm looking for a solution that's reliable across installations and OS versions.
I want it also to be fairly fast, so it can be used for example in setting shell
prompts.
There's a SuperUser thread[1] that talks about this. None of the solutions
seems completely satisfactory:
1. Run a command that only an Administrator can run, and check the return
status. But which one? Suggestions are:
 a. at. But at may not be on the $PATH, or supported.
 b. touch /cygdrive/c/Users/.x , or some other protected path. But which paths
are protected is installation-dependent (as is the /cygdrive prefix).
 c. editrights -l. On my host my unprivileged account can't even run this, so
I get a return status of 1. In a privileged shell I get 0 or 2. Is that
reliable?
 d. ??
2. Parse the output of groups or id -G. I can't find any reliable way to do
this. For example on my host, when I start a shell with "Run as administrator",
the new group I get isn't 544 (Administrators). It's 114 (Local account and
member of Administrators group). Is that at all portable or reliable?
What other ways are there?
Thanks,
Andrew
[1]
http://superuser.com/questions/660191/how-to-check-if-cygwin-mintty-bash-is-run-as-administrator
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