.\" Copyright (c) 1983 The Regents of the University of California. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms are permitted provided .\" that: (1) source distributions retain this entire copyright notice and .\" comment, and (2) distributions including binaries display the following .\" acknowledgement: ``This product includes software developed by the .\" University of California, Berkeley and its contributors'' in the .\" documentation or other materials provided with the distribution and in .\" all advertising materials mentioning features or use of this software. .\" Neither the name of the University nor the names of its contributors may .\" be used to endorse or promote products derived from this software without .\" specific prior written permission. .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. .\" .\" @(#)listen.2 6.4 (Berkeley) 6/23/90 .\" .TH LISTEN 2 "June 23, 1990" .UC 5 .SH NAME listen \- listen for connections on a socket .SH SYNOPSIS .nf .ft B listen(s, backlog) int s, backlog; .fi .SH DESCRIPTION To accept connections, a socket is first created with .IR socket (2), a willingness to accept incoming connections and a queue limit for incoming connections are specified with .IR listen (2), and then the connections are accepted with .IR accept (2). The .I listen call applies only to sockets of type SOCK_STREAM or SOCK_SEQPACKET. .PP The .I 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. .SH "RETURN VALUE A 0 return value indicates success; \-1 indicates an error. .SH "ERRORS The call fails if: .TP 20 [EBADF] The argument \fIs\fP is not a valid descriptor. .TP 20 [ENOTSOCK] The argument \fIs\fP is not a socket. .TP 20 [EOPNOTSUPP] The socket is not of a type that supports the operation \fIlisten\fP. .SH "SEE ALSO" accept(2), connect(2), socket(2) .SH BUGS The .I backlog is currently limited (silently) to 5.