listen - Listens for socket connections and limits the backlog of incoming connections
int listen (
int backlog );
Interfaces documented on this reference page conform to industry standards as follows:
Refer to the standards(5) reference page for more information about industry standards and associated tags.
Specifies the unique name for the socket. Specifies the maximum number of outstanding connection requests.
The listen() function identifies the socket that receives the connections, marks the socket as accepting connections, and limits the number (backlog) of outstanding connection requests in the system queue.
The maximum queue length (backlog) that the listen() function can specify is indicated by the SOMAXCONN value in the sys/socket.h header file.
Upon successful completion, the listen() function returns a value of 0 (zero). Otherwise, a value of -1 is returned and errno is set to indicate the error.
If the listen() function fails, errno may be set to one of the following values: The socket parameter is not valid. The socket is not bound to a local address, and the protocol does not support listening on an unbound socket. The socket is already connected. The socket parameter refers to a file, not a socket. The referenced socket is not a type that supports the listen() function.
Functions: accept(2), connect(2), socket(2)
Standards: standards(5) delim off