2.11BSD#431 - /usr/man/cat8/rmt.0

RMT(8)		    UNIX Programmer's Manual		   RMT(8)


NAME
     rmt - remote magtape protocol module

SYNOPSIS
     rmt

DESCRIPTION
     Rmt is a program used by the remote dump and restore pro-
     grams 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 manipula-
     tion 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

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

	  Eerror-number\nerror-message\n,

     where 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 pro-
     tocol is comprised of the following commands (a space is
     present between each token).

     O device mode  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.

     C device	    Close the currently open device.  The device
		    specified is ignored.

     L whence offset
		    Perform an lseek(2) operation using the
		    specified parameters.  The response value is
		    that returned from the lseek call.

     W count	    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.

     R count	    Read count bytes of data from the open


Printed 11/26/99	November 17, 1996			1


RMT(8)		    UNIX Programmer's Manual		   RMT(8)


		    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.

     I operation count
		    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 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 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 tempted to use this for a remote file access protocol
     are discouraged.


Printed 11/26/99	November 17, 1996			2