write - write to a file descriptor
ssize_t write(int fd, const void *buf, size_t count);
write writes up to count bytes to the file referenced by
the file descriptor fd from the buffer starting at buf.
POSIX requires that a read() which can be proved to occur
after a write() has returned returns the new data. Note
that not all file systems are POSIX conforming.
On success, the number of bytes written are returned (zero
indicates nothing was written). On error, -1 is returned,
and errno is set appropriately. If count is zero and the
file descriptor refers to a regular file, 0 will be
returned without causing any other effect. For a special
file, the results are not portable.
EBADF fd is not a valid file descriptor or is not open
EINVAL fd is attached to an object which is unsuitable for
EFAULT buf is outside your accessible address space.
EPIPE fd is connected to a pipe or socket whose reading
end is closed. When this happens the writing pro
cess will receive a SIGPIPE signal; if it catches,
blocks or ignores this the error EPIPE is returned.
EAGAIN Non-blocking I/O has been selected using O_NONBLOCK
and there was no room in the pipe or socket con
nected to fd to write the data immediately.
EINTR The call was interrupted by a signal before any
data was written.
ENOSPC The device containing the file referred to by fd
has no room for the data.
EIO A low-level I/O error occurred while modifying the
Other errors may occur, depending on the object connected
SVr4, SVID, POSIX, X/OPEN, 4.3BSD. SVr4 documents addi
tional error conditions EDEADLK, EFBIG, ENOLCK, ENOLNK,
ENOSR, ENXIO, EPIPE, or ERANGE. Under SVr4 a write may be
interrupted and return EINTR at any point, not just before
any data is written.
open(2), read(2), fcntl(2), close(2), lseek(2), select(2),
ioctl(2), fsync(2), fwrite(3)