NAME

listen − listen for connections on a socket

SYNOPSIS

cc [ flag ... ] file ... −lsocket −lnsl [ library ... ]

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

int listen(int s, int backlog);

DESCRIPTION

To accept connections, a socket is first created with socket(3N), a backlog for incoming connections is specified with listen() and then the connections are accepted with accept(3N).  The listen() call applies only to sockets 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 will receive an error with an indication of ECONNREFUSED for AF_UNIX sockets.  If the underlying protocol supports retransmission, the connection request may be ignored so that retries may succeed.  For AF_INET sockets, the tcp will retry the connection.  If the backlog is not cleared by the time the tcp times out, the connect will fail with ETIMEDOUT. 

RETURN VALUES

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

ERRORS

The call fails if:

EBADF The argument s is not a valid file descriptor. 

ENOTSOCK The argument s is not a socket. 

EOPNOTSUPP The socket is not of a type that supports the operation listen(). 

ATTRIBUTES

See attributes(5) for descriptions of the following attributes:

SEE ALSO

accept(3N), connect(3N), socket(3N), attributes(5), socket(5)

NOTES

There is currently no backlog limit. 

SunOS 5.6  —  Last change: 16 May 1997