WRITE(2)                 DOMAIN/IX SYS5                  WRITE(2)



NAME
     write - write on a file

USAGE
     int write(fildes, buf, nbyte)
     int fildes;
     char *buf;
     unsigned nbyte;


DESCRIPTION
     Fildes specifies a file descriptor generated by a creat,
     open, dup, fcntl, or pipe system call.

     Write attempts to write nbyte bytes from the buffer that buf
     points to, to the file associated with the fildes.

     On devices capable of seeking, write writes the data begin-
     ning at the position in the file that the file pointer
     specifies and, on return, increments the file pointer by the
     number of bytes actually written.

     On devices incapable of seeking, writing always takes place
     starting at the current position.  The value of a file
     pointer associated with such a device is undefined.

     If the O_APPEND flag of the file status flags is set, the
     file pointer will be set to the end of the file before each
     write.

RETURN VALUE
     A successful call returns the number of bytes actually writ-
     ten.  A failed call returns -1 and sets errno as indicated
     below.

ERRORS
     Write will fail and the file pointer will not change if one
     or more of the following is true:

     [EBADF]   Fildes is not a valid file descriptor open for
               writing.

     [EPIPE and SIGPIPE signal]
               An attempt is made to write to a pipe that is not
               open for reading by any process.

     [EFBIG]   An attempt is made to write a file that exceeds
               the process's file size limit or the maximum file
               size.




Printed 12/4/86                                           WRITE-1

WRITE(2)                 DOMAIN/IX SYS5                  WRITE(2)



     [EFAULT]  Buf points outside the process's allocated address
               space.

     [EINTR]   A signal was caught during the write system call.

     If a write requests that more bytes be written than there is
     room for (e.g., the physical end of a medium), it will write
     as many bytes as there is room for.  For example, if there
     is space for 20 bytes more in a file before reaching a
     limit, a write of 512  bytes will return 20.  The next
     attempt to write a non-zero number of bytes will return a
     failure.

     If the file being written is a pipe (or FIFO) and the
     O_NDELAY flag of the file flag word is set, then write to a
     full pipe (or FIFO) will return a count of zero.  If
     O_NDELAY is clear, writes to a full pipe (or FIFO) will
     block until space becomes available.

RELATED INFORMATION
     creat(2), dup(2), lseek(2), open(2), pipe(2),
































WRITE-2                                           Printed 12/4/86