Index for Section 8

Alphabetical listing for R

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rmt(8)
NAME
  rmt - Allows remote access to magnetic tape devices

SYNOPSIS
  rmt [debug-output-file]

DESCRIPTION
  The rmt command is started as a server process when requests from an rdump
  or rrestore call enter the system to operate a storage device through an
  interprocess communications connection.  After the remote programs have
  finished, rmt exits and will be started again at the next request.  The rmt
  command is normally invoked with an rexec or rcmd system call.

  This process performs the commands described in the following table and
  responds with a status indication to tell a user the result of the
  commanded process. When the rmt command is called with a filename specified
  as the debug-output-file parameter, all status responses are passed to the
  debug-output-file in ASCII and in one of two possible formats.
  Consequently, a system administrator can debug both software and hardware
  problems associated with previously issued backup commands to storage
  devices.

  Responses to successful commands are in the format:

       Anumber\n

  where A identifies a normal response, number is an integer that defines the
  number of the response as an ASCII integer, and \n is a newline in the C-
  language idiom.

  Responses to unsuccessful commands are in the format:

       Eerror_number  error_message\n

  where E identifies a response to an error, error_number is one of the
  possible error numbers values described in intro(2), error_message is the
  corresponding error-message string, which is output in response to a call
  to perror(3), and \n is a newline.

  Debug information returned by rmt is stored in the named debug-output-file
  file. The rmt command is called from the rdump or rrestore process with no
  file argument only when the debug-output-file parameter is specified.	 To
  activate the debug option of rmt your system administrator should rename
  the original rmt to rmt.ORG, for example, and create a new shell executable
  rmt that calls rmt.ORG debug-output-file.

				     Note
  The rdump command starts remote server /usr/sbin/rmt or /etc/rmt on the
  client machine to access the storage medium.	Another vendor's rdump
  command may fail because rmt is not located in /etc.	To avoid this
  problem, it may be necessary to provide a symbolic link on the Tru64 UNIX
  machine pointing to /usr/sbin/rmt as shown in the following example:

       ln -s /usr/sbin/rmt /etc/rmt


  All numerical arguments of the following commands are transferred as ASCII
  strings:

  O device flag
	    Opens the device, which must be a full pathname. The flag
	    parameter is a flag value suitable for the open system call.
	    When the device is successfully opened, the response is A0\n.

  C device  Closes the current open device.  When this command is successful,
	    the response is A0\n.

  L offset whence
	    Performs a seek operation. The offset and whence parameters have
	    the same significance as the offset and whence parameters of the
	    lseek system call. When this command successfully completes, the
	    response is An\n, where n has the same value returned by a
	    normally successful lseek system call.

  W count   Writes data to the device (see the O command above). The rmt
	    command reads count bytes from the connection. This process is
	    aborted when an EOF (End-of-File) is detected before the number
	    of characters specified by count is transferred. The response to
	    this command is An\n, where n is the number of characters
	    written.

  R count   Reads count bytes of data from the open device. When the value of
	    count exceeds the size of the data buffer (10 kilobytes), the
	    number of characters read is truncated to the data buffer size.
	    The rmt command then does the requested read operation. The
	    response to this command is An\n, where n is the number of
	    characters read.

  I operation count
	    Performs an ioctl system call on the open device.  The operation
	    parameter is a value passed to the mt_op member of a type mtop
	    structure for an MTIOCTOP ioctl (magnetic tape operation)
	    command. Valid values for the magnetic tape operations are
	    defined in the /usr/include/sys/mtio.h include file.  The count
	    parameter is the value to pass to the mt_count member of the type
	    mtop structure and specifies the number of operations performed
	    on the tape drive. The response to this command is An\n, where n
	    is the count.

  S	    Returns the status of the open device, which is obtained with a
	    MTIOCGET ioctl system call. A successful response to this command
	    is An\n, where n is the size of the status buffer, together with
	    the contents of the status buffer in binary.

FILES
  /usr/sbin/rmt
	    Specifies the command path

  /usr/include/errno.h
	    Describes the possible error numbers.

  /usr/include/sys/mtio.h
	    A header file that defines magnetic tape operations.


RELATED INFORMATION
  Commands:  rdump(8), rrestore(8).

  Functions: rcmd(3), rexec(3), open(2), ioctl(2)

Index for Section 8

Alphabetical listing for R

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