More C++ stuff... According to the man page on my Mac: If the call to confstr() is not successful, -1 is returned and errno is set appropriately. but the code in posix_confstr looks like: if (PyArg_ParseTuple(args, "O&:confstr", conv_confstr_confname, &name)) { int len = confstr(name, buffer, sizeof(buffer)); errno = 0; if (len == 0) { if (errno != 0) posix_error(); else result = PyString_FromString(""); } ... 1. Why is errno being set to 0? 2. Why is errno's value then tested to see if it's not zero? Looks like this have been that way since December 1999 when Fred added it. Skip