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 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 VALUE
       On  success,  zero is returned.  On error, -1 is returned,
       and errno is set appropriately.



ERRORS
       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.



HISTORY
       The listen function call appeared in BSD 4.2.



BUGS
       If the socket is of type af_inet, and the backlog argument
       is greater than 128 it is silently truncated to  128.  For
       portable  applications  don't rely on this value since BSD
       (and at least some BSD derived systems) limit the  backlog
       to 5.



SEE ALSO
       accept(2), connect(2), socket(2)