LISTEN(2) BSD Programmer's Manual LISTEN(2)NAME
listen - listen for connections on a socket
SYNOPSIS
#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(2), a will-
ingness to accept incoming connections and a queue limit for incoming
connections are specified with listen(), and then the connections are ac-
cepted with accept(2). 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 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. The backlog parameter is silent-
ly limited to a system defined value. This value may be inspected and
modified using sysctl(8) and the field name net.socket.maxconn.
RETURN VALUES
A 0 return value indicates success; -1 indicates an error.
ERRORSListen() will fail 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 ALSOaccept(2), connect(2), socket(2), sysctl(3), sysctl(8)HISTORY
The listen function call appeared in 4.2BSD.
4.2 Berkeley Distribution December 11, 1993 1