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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 option
      Opens the device, which must be a full pathname. The option parameter
      is a option 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

SEE ALSO
  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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