OSF

NAME

send − Sends messages on a socket

SYNOPSIS

#include <sys/types.h> #include <sys/socket.h> int send ( int socket,
char ∗message,
int length,
int flags );

PARAMETERS

socketSpecifies the unique name for the socket. 

messagePoints to the address of the message to send. 

lengthSpecifies the length of the message in bytes. 

flagsAllows the sender to control the transmission of the message.  The flags parameter to send a call is formed by logically ORing the values shown in the following list, defined in the sys/socket.h header file:

MSG_OOBSends out-of-band data on sockets that support out-of-band communication. 

MSG_DONTROUTE
Sends without using routing tables.  (Not recommended, for debugging purposes only.)

DESCRIPTION

The send() function sends a message only when the socket is connected.  The sendto() and sendmsg() functions can be used with unconnected or connected sockets. 

Specify the length of the message with the length parameter.  If the message is too long to pass through the underlying protocol, the system returns an error and does not transmit the message. 

No indication of failure to deliver is implied in a send() function.  A return value of -1 indicates only locally detected errors. 

If no space for messages is available at the sending socket to hold the message to be transmitted, the send() function blocks unless the socket is in a nonblocking I/O mode.  Use the select() function to determine when it is possible to send more data. 

NOTES

The send() function is identical to the sendto() function with a zero-valued dest_len parameter, and to the write() function if no flags are used.  For that reason, the send() function is disabled when 4.4BSD behavior is enabled (that is, when the _SOCKADDR_LEN compile-time option is defined). 

RETURN VALUES

Upon successful completion, the send() function returns the number of characters sent.  Otherwise, a value of -1 is returned and errno is set to indicate the error. 

ERRORS

If the send() function fails, errno may be set to one of the following values:

[EBADF]The socket parameter is not valid. 

[ENOTSOCK]
The socket parameter refers to a file, not a socket. 

[EFAULT]The message parameter is not in a readable or writable part of the user address space. 

[EMSGSIZE]The message is too large be sent all at once, as the socket requires. 

[EWOULDBLOCK]
The socket is marked nonblocking, and no space is available for the send() function. 

RELATED INFORMATION

Functions: recv(2), recvfrom(2), recvmsg(2), sendmsg(2), sendto(2), shutdown(2), connect(2), socket(2), getsockopt(2), select(2), setsockopt(2)