This module provides access to the function select() available in most operating systems. Note that on Windows, it only works for sockets; on other operating systems, it also works for other file types (in particular, on Unix, it works on pipes). It cannot be used on regular files to determine whether a file has grown since it was last read.
The module defines the following:
The return value is a triple of lists of objects that are ready: subsets of the first three arguments. When the time-out is reached without a file descriptor becoming ready, three empty lists are returned.
Amongst the acceptable object types in the lists are Python file
sys.stdin, or objects returned by
open() or os.popen()), socket objects
returned by socket.socket(),and the module stdwin which happens to
define a function
fileno()for just this purpose. You may
also define a wrapper class yourself, as long as it has an
appropriate fileno() method (that really returns a Unix
file descriptor, not just a random integer).