writev

writev

Writes Data from an Array of Buffers to a Socket

Portability: UNIX compatible

SYNOPSIS
DESCRIPTION
RETURN VALUE
PORTABILITY
RELATED FUNCTIONS

SYNOPSIS

#include <sys/types.h>
#include <sys/uio.h>
#include <fcntl.h>

int writev(int s, struct iovec *iov, int iovcnt);

DESCRIPTION

writev writes data to connected socket descriptor s from the iovcnt buffers specified by the iov array. As with the write call, the socket must have been previously associated with a remote address via the connect system call. If there are no data, writev blocks the caller unless the socket is in non-blocking mode. The iovec structure is defined in the <sys/uio.h> header file. Each iovec entry specifies the base address and length of an area in memory from which the data should be taken. writev completely sends one area before proceeding to the next area.

writev is an atomic operation. For datagram sockets, each writev call causes one datagram to be sent.

Note: Although writev is primarily used with sockets, it can also be used to write any file that can be accessed by the write function. [cautionend]

RETURN VALUE

If writev succeeds, it returns the number of bytes written. If writev returns a 0 , the end-of-file has been reached. If writev fails, it returns a -1 .

PORTABILITY

writev is portable to other environments, including most UNIX systems, that implement BSD sockets.

RELATED FUNCTIONS

connect , recv , recvfrom , recvmsg , read , readv , write

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