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RMT(8)                      System Manager's Manual                     RMT(8)

NAME
     rmt - remote magtape protocol module

SYNOPSIS
     rmt

DESCRIPTION
     rmt is a program used by the remote dump and restore programs in
     manipulating a magnetic tape drive through an interprocess communication
     connection.  rmt is normally started up with an rexec(3) or rcmd(3) 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\n

     Number is an ASCII representation of a decimal number.  Unsuccessful
     commands are responded to with:

           Eerror-number\nerror-message\n

     Error-number 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(3).  The protocol comprises the following commands, which
     are sent as indicated - no spaces are supplied between the command and
     its arguments, or between its arguments, and `\n' indicates that a
     newline should be supplied:

     Odevice\nmode\n
             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).  If a device had already
             been opened, it is closed before a new open is performed.

     Cdevice\n
             Close the currently open device.  The device specified is
             ignored.

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

     Wcount\n
             Write data onto the open device.  rmt reads count bytes from the
             connection, aborting if a premature end-of-file is encountered.
             The response value is that returned from the write(2) call.

     Rcount\n
             Read count bytes of data from the open device.  If count exceeds
             the size of the data buffer (10 kilobytes), it is truncated to
             the data buffer size.  rmt then performs the requested read(2)
             and responds with Acount-read\n if the read was successful;
             otherwise an error in the standard format is returned.  If the
             read was successful, the data read is then sent.

     Ioperation\ncount\n
             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 mt_op and
             mt_count fields of the structure used in the ioctl(2) 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, an ``ack'' is
             sent with the size of the status buffer, then the status buffer
             is sent (in binary).

     Any other command causes rmt to exit.

DIAGNOSTICS
     All responses are of the form described above.

SEE ALSO
     rcmd(3), rexec(3), mtio(4), rdump(8), rrestore(8)

HISTORY
     The rmt command appeared in 4.2BSD.

BUGS
     People should be discouraged from using this for a remote file access
     protocol.

NetBSD 10.99                     June 1, 1994                     NetBSD 10.99