listen - listen for connections on a socket
listen(int s, int backlog);
To accept connections, a socket is first created with socket(2), a willingness
to accept incoming connections and a queue limit for
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
connections may grow to. If a connection request arrives
with the queue
full the client may receive an error with an indication of
or, if the underlying protocol supports retransmission, the
be ignored so that retries may succeed.
A 0 return value indicates success; -1 indicates an error.
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
accept(2), connect(2), socket(2)
The listen() function call appeared in 4.2BSD.
The backlog is currently limited (silently) to 128.
OpenBSD 3.6 December 11, 1993
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