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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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LISTEN(3P) POSIX Programmer's Manual LISTEN(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
listen — listen for socket connections and limit the queue of
incoming connections
#include <sys/socket.h>
int listen(int socket, int backlog);
The listen() function shall mark a connection-mode socket,
specified by the socket argument, as accepting connections.
The backlog argument provides a hint to the implementation which
the implementation shall use to limit the number of outstanding
connections in the socket's listen queue. Implementations may
impose a limit on backlog and silently reduce the specified
value. Normally, a larger backlog argument value shall result in
a larger or equal length of the listen queue. Implementations
shall support values of backlog up to SOMAXCONN, defined in
<sys/socket.h>.
The implementation may include incomplete connections in its
listen queue. The limits on the number of incomplete connections
and completed connections queued may be different.
The implementation may have an upper limit on the length of the
listen queue—either global or per accepting socket. If backlog
exceeds this limit, the length of the listen queue is set to the
limit.
If listen() is called with a backlog argument value that is less
than 0, the function behaves as if it had been called with a
backlog argument value of 0.
A backlog argument of 0 may allow the socket to accept
connections, in which case the length of the listen queue may be
set to an implementation-defined minimum value.
The socket in use may require the process to have appropriate
privileges to use the listen() function.
Upon successful completions, listen() shall return 0; otherwise,
-1 shall be returned and errno set to indicate the error.
The listen() function shall fail if:
EBADF The socket argument is not a valid file descriptor.
EDESTADDRREQ
The socket is not bound to a local address, and the
protocol does not support listening on an unbound socket.
EINVAL The socket is already connected.
ENOTSOCK
The socket argument does not refer to a socket.
EOPNOTSUPP
The socket protocol does not support listen().
The listen() function may fail if:
EACCES The calling process does not have appropriate privileges.
EINVAL The socket has been shut down.
ENOBUFS
Insufficient resources are available in the system to
complete the call.
The following sections are informative.
None.
None.
None.
None.
accept(3p), connect(3p), socket(3p)
The Base Definitions volume of POSIX.1‐2017, sys_socket.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 LISTEN(3P)
Pages that refer to this page: sys_socket.h(0p), accept(3p), bind(3p), socket(3p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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