int socket (
int protocol );
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 communications domain in which a socket is to be created. The domain argument specifies the address family with which addresses specified in later socket operations should be interpreted. The sys/socket.h file contains the definitions of the address families. Commonly used families are: UNIX pathnames ARPA Internet addresses Specifies the semantics of communication. The sys/socket.h file defines the socket types. The following types are supported: Provides sequenced, reliable, two-way byte streams with a transmission mechanism for out-of-band data. Provides datagrams, which are connectionless messages of a fixed maximum length. [Digital] Provides access to internal network protocols and interfaces. This type of socket is available only to a process with superuser privilege. Specifies a particular protocol to be used with the socket. Specifying a protocol of 0 (zero) causes the socket() function to default to the typical protocol for the requested type of returned socket.
The socket() function creates a socket of the specified type in the specified domain.
The socket() function returns a descriptor (an integer) that can be used in later system calls that operate on sockets.
Socket level options control socket operations. The getsockopt() and setsockopt() functions are used to get and set these options, which are defined in the sys/socket.h file.
Upon successful completion, the socket() function returns a nonnegative integer (the socket descriptor). Otherwise, a value of -1 is returned and errno is set to indicate the error.
If the socket() function fails, errno may be set to one of the following values: The process have not have appropriate privileges. The addresses in the specified address family are not available in the kernel. The per-process descriptor table is full. No more file descriptors are available for the system. Insufficient resources were available in the system to complete the call. The system was unable to allocate kernel memory to increase the process descriptor table. The process is attempting to open a raw socket and does not have superuser privilege. The socket in the specified address family is not supported. The socket type is not supported by the protocol.
Functions: accept(2), bind(2), connect(2), listen(2), getsockname(2), getsockopt(2), recv(2), recvfrom(2), recvmsg(2), send(2), sendto(2), sendmsg(2), setsockopt(2), shutdown(2), socketpair(2)
Standards: standards(5) delim off