rmt(1M)                        DG/UX 5.4R3.00                        rmt(1M)


NAME
       rmt - start the remote mag tape server

SYNOPSIS
       rmt

DESCRIPTION
       Rmt is a server process used by the remote dump(1M), dump2(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 manipulation 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<NL>

       where number is an ASCII representation of a decimal number, and <NL>
       is the new-line character.  Unsuccessful commands are responded to
       with:

          Eerrnoval<NL>errormessage<NL>

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

       The protocol consists of the following commands:

       Odevice<NL>mode<NL>
       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<NL>
       Close the currently open device.  The device specified is ignored.  A
       successful response number should not be interpreted.

       Rcount<NL>
       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<NL>
       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.



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rmt(1M)                        DG/UX 5.4R3.00                        rmt(1M)


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

       Ioperation<NL>count<NL>
       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<NL>
       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
       dump(1M), dump2(1M), mt(1), pmtd(1M), restore(1M), intro(2), exit(2),
       ioctl(2), lseek(2), open(2), read(2), write(2), perror(3C), rcmd(3X),
       rexec(3X).

NOTES
       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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