listen(3socket) [sunos man page]
listen(3SOCKET) Sockets Library Functions listen(3SOCKET) NAME
listen - listen for connections on a socket SYNOPSIS
cc [ flag ... ] file ... -lsocket -lnsl [ library ... ] #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(3SOCKET), a backlog for incoming connections is specified with listen() and then the connections are accepted with accept(3SOCKET). 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 will receive an error with an indication of ECONNREFUSED for AF_UNIX sock- ets. If the underlying protocol supports retransmission, the connection request may be ignored so that retries may succeed. For AF_INET and AF_INET6sockets, the TCP will retry the connection. If the backlog is not cleared by the time the tcp times out, the connect will fail with ETIMEDOUT. RETURN VALUES
A 0 return value indicates success; -1 indicates an error. ERRORS
The call fails if: EBADF The argument s is not a valid file descriptor. ENOTSOCK The argument s is not a socket. EOPNOTSUPP The socket is not of a type that supports the operation listen(). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |Safe | +-----------------------------+-----------------------------+ SEE ALSO
accept(3SOCKET), connect(3SOCKET), socket(3SOCKET), attributes(5), socket.h(3HEAD) NOTES
There is currently no backlog limit. SunOS 5.10 8 Nov 1999 listen(3SOCKET)
Check Out this Related Man Page
LISTEN(2) Linux Programmer's Manual LISTEN(2) NAME
listen - listen for connections on a socket 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 incom- ing 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 succeed. NOTES
The behaviour of the backlog parameter on TCP sockets changed with Linux 2.2. Now it specifies the queue length for completely established sockets waiting to be accepted, instead of the number of incomplete connection requests. The maximum length of the queue for incomplete sockets can be set using the tcp_max_syn_backlog sysctl. When syncookies are enabled there is no logical maximum length and this sysctl setting is ignored. See tcp(7) for more information. RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately. ERRORS
EADDRINUSE Another socket is already listening on the same port. 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 listen operation. CONFORMING TO
Single Unix, 4.4BSD, POSIX 1003.1g draft. The listen function call first appeared in 4.2BSD. BUGS
If the socket is of type AF_INET, and the backlog argument is greater than the constant SOMAXCONN (128 in Linux 2.0 & 2.2), it is silently truncated to SOMAXCONN. Don't rely on this value in portable applications since BSD (and some BSD-derived systems) limit the backlog to 5. SEE ALSO
accept(2), connect(2), socket(2) BSD Man Page 1993-07-23 LISTEN(2)