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().
SEE ALSO
accept(2),
connect(2),
socket(2)
HISTORY
The
listen() function call appeared in
4.2BSD.
BUGS
The
backlog is currently limited (silently) to 128.