rmt(1M) — DG/UX 4.30



     rmt(1M)                    DG/UX 4.30                     rmt(1M)



     NAME
          rmt - start the remote mag tape daemon

     SYNOPSIS
          /etc/rmt

     DESCRIPTION
          Rmt is a server process used by the remote dump(1M),
          restore(1M), and pmtd(1M) programs in manipulating a
          magnetic tape drive through an interprocess communication
          connection.  Rmt is normally started up with an rexec(3X) or
          rcmd(3X) call.

          The rmt program accepts requests specific to the
          manipulalation of magnetic tapes, performs the commands,
          then responds with a status indication.  All responses are
          in ASCII and in one of two forms.  Successful commands have
          responses of:

             Anumber

          where number is an ASCII representation of a decimal number,
          and  is the New Line character.  Unsuccessful commands are
          responded to with:

             Eerrno_valerror_message

          where errno_val is one of the possible error numbers
          described in intro(2), and error_message is the
          corresponding error string as printed from a call to
          perror(3C).

          The protocol consists of the following commands:

          Odevicemode

          Open the specified device using the indicated mode.  device
          is a full pathname and mode is an ASCII representation of a
          decimal number suitable for passing to open(2).  A
          successful response number should not be interpreted.  If
          rmt receives additional open commands, the currently open
          device is closed before the new open is performed.


          Cdevice

          Close the currently open device.  The device specified is
          ignored.  A successful response number should not be
          interpreted.


          Rcount



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     rmt(1M)                    DG/UX 4.30                     rmt(1M)



          Read count bytes of data from the open device.  Rmt performs
          the requested read(2) and responds with the value returned
          from the read(2) call if the read was successful; otherwise
          an error in the standard format is returned.  The data read
          is sent immediately after the response if the read was
          successful.


          Wcount

          Write data onto the open device.  Rmt reads count bytes from
          the connection, aborting if a premature EOF is encountered,
          and writes that data to the open device.  The response value
          is that returned from the write(2) call.


          Lwhenceoffset

          Perform an lseek(2) operation using the specified
          parameters.  The response value is that returned from the
          lseek(2) call.


          Ioperationcount

          Perform a MTIOCOP ioctl(2) command using the specified
          parameters.  The parameters are interpreted as the ASCII
          representations of the decimal values to place in the mtop
          and mtcount fields of the structure used in the ioctl call.
          The return value is the count parameter when the operation
          is successful.


          S

          Return the status of the open device, as obtained with a
          MTIOCGET ioctl(2) call.  If the operation was successful,
          the size of the status buffer and then the status buffer
          contents are sent.  Interpretation of the status buffer
          contents is implementation specific.

          Any other command causes rmt to exit(3C).

          Rmt reads requests from standard input and writes responses
          to standard output.

     SEE ALSO
          pmtd(1M), dump(1M), restore(1M), intro(2), ioctl(2),
          lseek(2), open(2), read(2), write(2), exit(3C), perror(3C),
          rcmd(3X), rexec(3X), mtio(4)

     CAVEATS



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     rmt(1M)                    DG/UX 4.30                     rmt(1M)



          Use rmt(1M) for remote tape access only, not for remote file
          access.  Different operating systems and different hardware
          may perform device I/O in different ways.  In particular
          lseek, ioctl, and status requests may operate differently.
          Systems may differ so much that these operations are no
          longer functionally the same on different machines.

















































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