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RMT(8)			     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 manipu-
     lating a magnetic tape drive through an interprocess communication  connec-
     tion.  It is normally started up with an 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.	Successful commands have
     responses of:

	   Anumber\n

     Number is an ASCII representation of a decimal number.   Unsuccessful  com-
     mands 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 is comprised of the following commands, which  are
     sent  as indicated - no spaces are supplied between the command and its ar-
     guments, 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 num-
	     ber  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, aborting if a premature end-of-file is encoun-
	     tered.  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 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), mtio(4), rdump(8), rrestore(8)

HISTORY
     The rmt utility appeared in 4.2BSD.

BUGS
     People  should be discouraged from using this for a remote file access pro-
     tocol.

FreeBSD 15.1			  June 1, 1994				  RMT(8)
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