VWRITE(2V)              GENIX Programmer's Manual              VWRITE(2V)



      NAME
           vwrite - write (virtually) to file

      SYNOPSIS
           vwrite(filedes, buffer, nbytes)
           char *buffer;

      DESCRIPTION
           N.B.: This call is likely to be replaced  by  more  general  virtual
           memory facilities in the near future.

           The vwrite system call is used in conjunction with vread to  perform
           efficient updating of large files.  After a call to vread and updat-
           ing of the data in the buffer which was given to vread, a vwrite  of
           the  same  buffer to the same filedes at the same offset in the file
           will cause data which has been modified since it was vread from  (or
           vwritten to) the file to be returned to the file.

           On the NS16000, vwrite is equivalent to write.

      SEE ALSO
           vread(2)

      DIAGNOSTICS
           Returns -1 on error: bad descriptor, buffer address, count or align-
           ment as well as on physical I/O errors.

      BUGS
           This call is peculiar to this version of UNIX.  It  will  be  super-
           seded  by  more general virtual memory facilities in future versions
           of the system.
























      Printed 11/16/83                                                        1