SEND(2)
NAME
send, sendto, sendmsg − send a message from a socket
USAGE
#include <sys/types.h>
#include <sys/socket.h>
cc = send(s, msg, len, flags)
int cc, s;
char *msg;
int len, flags;
cc = sendto(s, msg, len, flags, to, tolen)
int cc, s;
char *msg;
int len, flags;
struct sockaddr *to;
int tolen;
cc = sendmsg(s, msg, flags)
int cc, s;
struct msghdr msg[];
int flags;
DESCRIPTION
Send, sendto, and sendmsg are transmit messages to another socket. Send can be used only when the socket is connected, while sendto and sendmsg can be used at any time.
The address of the target is given by to, and tolen specifies its size. The length of the message is given by len. If the message is too long to pass through the underlying protocol, the error EMSGSIZE is returned, and the message is not transmitted. Return values of −1 indicate some locally detected errors.
If no message space is available at the socket to hold the message to be transmitted, send normally blocks, unless the socket has been placed in non-blocking I/O mode. The select(2) call may be used to determine when it is possible to send more data.
The flags parameter may be set to MSG_OOB to send “out-of-band” data on sockets which support this form (e.g., SOCK_STREAM).
See recv(2) for a description of the msghdr structure.
RETURN VALUE
The call returns the number of characters sent, or −1 if an error occurred.
ERRORS
[EBADF] An invalid descriptor was specified.
[ENOTSOCK] The argument s is not a socket.
[EFAULT] An invalid user space address was specified for a parameter.
[EMSGSIZE] The socket requires that message be sent in one piece. The size of the message to be sent made this impossible.
[EWOULDBLOCK] The socket is marked non-blocking and the requested operation would block.