LISTEN(2)                        System Calls                        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 ECON‐
       NREFUSED, 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)

BUGS

       The backlog is currently limited (silently) to 32.

HISTORY

       The listen function call appeared in 4.2BSD.  The first  appearance  in
       GNO was in v2.0.5.



GNO                             16 January 1997                      LISTEN(2)