I have a CGI script that is getting an "IOError: [Errno 13] Permission denied" error in the stack trace in the web server's error log.
As part of debugging this problem, I'd like to add a little bit of code to the script to print the user and (especially) group that the script is running as, into the error log (presumably STDERR).
I know I can just print the values to sys.stderr, but how do I figure out what user and group the script is running as?
(I'm particularly interested in the group, so the $USER environment variable won't help; the CGI script has the setgid bit set so it should be running as group "list" instead of the web server's "www-data" - but I need code to see if that's actually happening.)
os.getgid() and os.getuid() can be useful.  For other environment variables, look into os.getenv.  For example, os.getenv('USER') on my Mac OS X returns the username. os.getenv('USERNAME') would return the username on Windows machines.
How to determine what user and group a Python script is running as?