Listens for connection requests on a socket.

int listen(
  int s,
  int backlog
);

Parameters

s

An unconnected socket of type SOCK_STREAM, which has been bound to a name with bind.

backlog

The maximum number of incoming connection requests that can be queued. If a connection request arrives with the queue full, the client will receive an error.

Remarks

For a server application to accept connections, it must first create a socket with socket( ), then specify a backlog for incoming connection requests with listen. To complete a connection, accept connection requests with accept.

A listen(s, 0) call succeeds and sets a connection queue length of 0. This causes all connect attempts to the listening port to fail, an error. A listen(s, 1) call accepts only a single connection with no pending requests allowed.

Return Values

0 (zero)

Success.

-1 and the function sets errno to one of these values

EBADF	Invalid file descriptor or file not opened for writing.
ENOSPC	No space left on device.

Failure.

Requirements