Editing Berkeley sockets (section)

===listen===
After a socket has been associated with an address, <var>listen()</var> prepares it for incoming connections. However, this is only necessary for the stream-oriented (connection-oriented) data modes, i.e., for socket types (<var>SOCK_STREAM</var>, <var>SOCK_SEQPACKET</var>). <var>listen()</var> requires two arguments:
* <var>sockfd</var>, a valid socket descriptor.
* <var>backlog</var>, an integer representing the number of pending connections that can be queued up at any one time. The operating system usually places a cap on this value.
Once a connection is accepted, it is dequeued. On success, 0 is returned. If an error occurs, -1 is returned.