bsd man page for listen

LISTEN(2)							System Calls Manual							 LISTEN(2)

NAME
       listen - listen for connections on a socket

SYNOPSIS
       listen(s, backlog)
       int s, backlog;

DESCRIPTION
       To  accept connections, a socket is first created with socket(2), a willingness to accept incoming connections and a queue limit for incom-
       ing connections are specified with listen(2), and then the connections are accepted with accept(2).  The listen call applies only to  sock-
       ets of type SOCK_STREAM or SOCK_SEQPACKET.

       The  backlog  parameter	defines the maximum length the queue of pending connections may grow to.  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
       A 0 return value indicates success; -1 indicates an error.

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

BUGS
       The backlog is currently limited (silently) to 5.

4.2 Berkeley Distribution					   May 14, 1986 							 LISTEN(2)