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RMT(8)			FreeBSD	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 manipu-
     lating a magnetic tape drive through an interprocess communication	con-
     nection.  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 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 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	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; oth-
	     erwise 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 parame-
	     ters.  The	parameters are interpreted as the ASCII	representa-
	     tions 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)

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

HISTORY
     The rmt command appeared in 4.2BSD.

FreeBSD	10.1			 June 1, 1994			  FreeBSD 10.1

NAME | SYNOPSIS | DESCRIPTION | DIAGNOSTICS | SEE ALSO | BUGS | HISTORY

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