NAME
listen
—
listen for connections on a
socket
LIBRARY
library “libc”
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 withlisten
(),
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
HISTORY
The listen
() function call appeared in
4.2BSD.
BUGS
The backlog is currently limited (silently) to 128.