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LISTEN(2) |
System Calls Manual |
LISTEN(2) |
NAME
listen — listen for connections on a socket
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/socket.h>
int
listen(int s, int backlog);
DESCRIPTION
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(), and then the connections are accepted 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.
RETURN VALUES
A 0 return value indicates success; -1 indicates an error.
ERRORS
listen() 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().
HISTORY
The listen() function call appeared in 4.2BSD.
BUGS
The backlog is currently limited (silently) to 128.
