LISTEN(2)							     LISTEN(2)

NAME    [Toc]    [Back]

     listen - listen for connections on	a socket

SYNOPSIS    [Toc]    [Back]

     #include <sys/types.h>
     #include <sys/socket.h>

     int listen	(int s,	int backlog);

DESCRIPTION    [Toc]    [Back]

     To	accept connections, a socket is	first created with socket(2), a
     willingness to accept incoming connections	and a queue limit for incoming
     connections are specified with listen(2), and then	each new connection is
     accepted with accept(2).  The listen call applies only to sockets of type
     SOCK_STREAM.

     The backlog parameter defines the maximum length the queue	of pending
     connections.  If a	connection request arrives with	the queue full the
     client may	receive	an error with an indication of ECONNREFUSED, or, if
     the underlying protocol supports retransmission, the request may be
     ignored so	that retries may succeed.

RETURN VALUE    [Toc]    [Back]

     A 0 return	value indicates	success; -1 indicates an error.

ERRORS    [Toc]    [Back]

     The call fails if:

     [EBADF]		 The argument s	is not a valid descriptor.

     [ENOTSOCK]		 The argument s	is not a socket.

     [EOPNOTSUPP]	 The socket is not of a	type that supports the
			 operation listen.

SEE ALSO    [Toc]    [Back]

     accept(2),	connect(2), socket(2)

NOTES    [Toc]    [Back]

     The backlog is currently limited (silently) to 1000.

     The system	actually enforces the limit of pending connections as
	       ((3 * backlog) /	2) + 1
     For example, a backlog of 32 will allow 49	outstanding connections.

     ABI-compliant versions of the above call can be obtained from
     libsocket.so.


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