> As you can see, IOError covers many issues
>
> >>> try:
> ... fd = open('/home/shoon/xinitrc')
> ... except IOError, e:
> ... print e[0], e[1]
> ...
> 13 Permission denied
>
> I am sure there is a wrapper for errno somewhere in python.
Here you go:
http://www.python.org/doc/lib/module-errno.html
Hope this helps!