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listen(2)							    listen(2)



NAME

  listen - Listens for socket connections and limits the backlog of incoming
  connections

SYNOPSIS

  #include <&lt;sys/socket.h>&gt;
  int listen (
	  int socket,
	  int backlog );

STANDARDS

  Interfaces documented	on this	reference page conform to industry standards
  as follows:

  listen():  XNS5.0

  Refer	to the standards(5) reference page for more information	about indus-
  try standards	and associated tags.

PARAMETERS

  socket    Specifies the unique name for the socket.

  backlog   Specifies the maximum number of outstanding	connection requests.

DESCRIPTION

  The listen() function	identifies the socket that receives the	connections,
  marks	the socket as accepting	connections, and limits	the number (backlog)
  of outstanding connection requests in	the system queue.

  The maximum queue length (backlog) that the listen() function	can specify
  is indicated by the somaxconn	kernel attribute in the	socket subsystem.
  Use the sysconfig -q socket somaxconn	to obtain this value from the kernel.
  See sys_attrs_socket(5) for more information.

  The socket in	use may	require	that the process have appropriate privileges
  to use the listen() function.

RETURN VALUES

  Upon successful completion, the listen() function returns a value of 0
  (zero).  Otherwise, a	value of -1 is returned	and errno is set to indicate
  the error.

ERRORS

  If the listen() function fails, errno	may be set to one of the following
  values:

  [EACCES]  The	requested address is protected and the current process does
	    not	have permission	to access it.

  [EBADF]   The	socket parameter is not	valid.

  [EDESTADDRREQ]
	    The	socket is not bound to a local address,	and the	protocol does
	    not	support	listening on an	unbound	socket.

  [EINVAL]  The	socket is already connected; or	the socket is shut down.

  [ENOBUFS] Insufficient resources are available in the	system to complete
	    the	call.

  [ENOTSOCK]
	    The	socket parameter refers	to a file, not a socket.

  [EOPNOTSUPP]
	    The	referenced socket is not a type	that supports the listen()
	    function.

RELATED	INFORMATION

  Functions: accept(2),	connect(2), socket(2)

  Standards: standards(5)