NAME

     write - write to a file descriptor

SYNOPSIS

     #include <unistd.h>

     ssize_t write(int fd, const void *buf, size_t count

DESCRIPTION

     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.

RETURN VALUE

     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.

ERRORS

     EBADF
          fd is not a valid file descriptor or is  not  open  for
          writing.

     EINVAL
          fd is attached to an object  which  is  unsuitable  for
          writing.

     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 process 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 connected 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
          inode.

     Other errors may occur, depending on the object connected to
     fd.

CONFORMING TO

     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.

SEE ALSO

     open(2), read(2), fcntl(2), close(2),  lseek(2),  select(2),
     ioctl(2), fsync(2), fwrite(3).