Return the program name as invoked on the command line.

Value is a string.

Set the program name.

Value has to be a string, a pathname, or a file stream.

Return the program name as invoked on the command line
but without the directory part.

Value is a string.

Return the list of program arguments.

Value is a list of strings.

Set the list of program arguments.

Value has to be a list of strings.