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listen(2) [netbsd man page]

LISTEN(2)						      BSD 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(). 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. BSD
December 11, 1993 BSD

Check Out this Related 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 5.11 8 Nov 1999 listen(3SOCKET)
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