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 rmt(1M)							     rmt(1M)




 NAME
      rmt - remote magnetic-tape protocol module

 SYNOPSIS
      /usr/sbin/rmt

 DESCRIPTION
      rmt is a program used by the remote dump and restore programs for
      manipulating a magnetic tape drive through an interprocess
      communication (IPC) connection.  The fbackup and frecover commands
      also use rmt to achieve remote backup capability (see fbackup(1M) and
      frecover(1M)).  rmt is normally started up with an rexec() or rcmd()
      call (see rexec(3N) and rcmd(3N)).

      rmt accepts requests specific to the manipulation of magnetic tapes,
      performs the commands, then responds with a status indication.  DDS
      devices that emulate magnetic tapes are also supported.  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
      errno(2) and error-message is the corresponding error string as
      printed from a call to perror() (see perror(3C)).	 The protocol is
      comprised of the following commands:

	   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() (see open(2)).  If a device is
				already open, it is closed before a new open
				is performed.

	   odevice\nmode\n	Open the specified device using the
				indicated mode.	 device is a full pathname
				and mode is an ASCII representation of an
				octal number suitable for passing to open().
				If a device is already open, it is closed
				before a new open is performed.

	   Cdevice\n		Close the currently open device.  The device
				specified is ignored.





 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 rmt(1M)							     rmt(1M)




	   Lwhence\noffset\n	Perform an lseek() operation using the
				specified parameters (see lseek(2)).  The
				response value is that returned from by
				lseek().

	   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 by
				write() (see write(2)).

	   Rcount\n		Read count bytes of data from the open
				device.	 If count exceeds the size of the
				data buffer (10 Kbytes), it is truncated to
				the data buffer size.  rmt then performs the
				requested read() and responds with Acount-
				read\n if the read was successful.
				Otherwise an error is returned in the
				standard format.  If the read was
				successful, the data read is then sent.

	   Ioperation\ncount\n	Perform a MTIOCOP ioctl() command using the
				specified parameters.  Parameters are
				interpreted as ASCII representations of the
				decimal values to be placed 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).

	   s			Return the status of the open device, as
				obtained with a fstat() 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).  f Return
				the status of the open device, as obtained
				with a fstat() call.  If the operation was
				successful, an ACK is sent with the size of
				the status buffer, then the status buffer is
				sent in the following ASCII format:

				     machine<blank>value<newline>
				     stat_struct_member_name<blank>value<newline>

				The end of the data is indicated by an ASCII
				NULL character.	 See /usr/include/sys/stat.h



 Hewlett-Packard Company	    - 2 -   HP-UX Release 11i: November 2000






 rmt(1M)							     rmt(1M)




				for the struct stat definition.	 In addition
				to the struct stat information, there is an
				entry in the buffer describing the machine
				type as returned from a uname() call (see
				uname(2)).  In the above format ``machine''
				is a key word.	All fields except st_spare4
				of the struct stat are returned.

	   m			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 the following ASCII
				format:

				     machine<blank>value<newline>
				     mtget_struct_member_name<blank>value<newline>

				The end of the data is indicated by an ASCII
				NULL character.	 See /usr/include/sys/mtio.h
				for the struct mtget definition.  In
				addition to the struct mtget information
				there is an entry in the buffer describing
				the machine type as returned from a uname()
				call.  In the above format ``machine'' is a
				keyword.

      Any other command causes rmt to exit.

 RETURN VALUE
      Device status is returned in the field mt_gstat.
      /usr/include/sys/mtio.h contains defined macros for checking the
      status bits.

 DIAGNOSTICS
      All responses are of the form described above.

 AUTHOR
      rmt was developed by the University of California, Berkeley.

 SEE ALSO
      ftio(1), fbackup(1M), frecover(1M), dump(1M), restore(1M), rcmd(3N),
      rexec(3N).

 WARNINGS
      Use of this command for remote file access protocol is discouraged.








 Hewlett-Packard Company	    - 3 -   HP-UX Release 11i: November 2000