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

NAME
     rmt -- remote magtape protocol module

SYNOPSIS
     rmt

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

     The rmt utility 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.  Success-ful Successful
     ful 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 corre-sponding corresponding
     sponding error string as printed from a call to perror(3).  The protocol is comprised of 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.

     Lwhence\noffset\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.  The rmt utility reads count bytes from the connection, abort-ing aborting
             ing 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.  The rmt utility 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 inter-preted interpreted
             preted 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 opera-tion operation
             tion 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)

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

HISTORY
     The rmt utility appeared in 4.2BSD.

BSD                                             June 1, 1994                                             BSD