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listen(2) System Calls Manual listen(2) NAME
listen - Listens for socket connections and limits the backlog of incoming connections SYNOPSIS
#include <sys/socket.h> int listen ( int socket, int backlog ); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: listen(): XNS5.0 Refer to the standards(5) reference page for more information about industry standards and associated tags. PARAMETERS
Specifies the unique name for the socket. Specifies the maximum number of outstanding connection requests. DESCRIPTION
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. The socket in use may require that the process have appropriate privileges to use the listen() function. RETURN VALUES
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. ERRORS
If the listen() function fails, errno may be set to one of the following values: The requested address is protected and the current process does not have permission to access it. 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; or the socket is shut down. Insufficient resources are available in the system to complete the call. The socket parameter refers to a file, not a socket. The referenced socket is not a type that supports the listen() function. RELATED INFORMATION
Functions: accept(2), connect(2), socket(2) Standards: standards(5) delim off listen(2)