mt-dds(1)						      General Commands Manual							 mt-dds(1)

NAME

       mt-dds - tool to control a dds device.

SYNOPSIS

       mt-dds comp-on|comp-off|comp-query|comp-log
       mt-dds < tell|label > [ -b  # ]

DESCRIPTION

       mt-dds controls the compression mode of dds tape devices (DAT).

       mt-dds  may  also  report  the  current tape position in absolute records (relative to begin of tape) in a format that may be used later by
       dds2tar(1) to access tar archives that are not the first file on tape.

       The default device is /dev/nst0, which may be overridden with the environment variable TAPE, which in  turn  may  be  overridden  with  the
       -f device option. The device must be a character special file.

OPTIONS

   DDS tape device control options
       comp-on
	      Enable the hardware compression mode if supported by the device.

       comp-off
	      Disable the compression mode, switch to normal mode.

       comp-query
	      Print  to  stderr if compression mode currently is disabled or enabled.  A 0 means compression is disabled, a 1 means compression in
	      enabled.

       comp-log
	      Print to stdout four lines of information about transferred kilobytes before and after hardware compression from and to  the  device
	      since initialization.

   dds2tar service functions
       tell   Print  three  lines with the current tape position, a block size value (20 by default, may be overridden with -b option) and a block
	      length value (blocksize*512) to stdout.  If this output is redirected to	a  location  file  locfile,  this  file  may  be  used	by
	      dds2tar(1) to access archives on tape.

       label  If  the current tape position is the beginning of an archive and the archive is labeled, mt-dds writes the label to stdout and moves
	      the tape back to the current position (or back over the filemark).

       ts     If the current tape position is the beginning of an archive and the archive is labeled, mt-dds writes the timestamp in octal  format
	      to  stdout  and  moves  the  tape back to the current position (or back over the filemark).  If you are using only one computer, the
	      timestamp can be used as a unique archive identifier.

       -b #   Specify the block size # value that is used as a default for the written value with the mt-dds tell command (see above).	 Also  the
	      internal	buffer	size  is  specified with this option which is used to read one block in order to get the block size of the current
	      tape block. So specify the block size of the archive or a larger number.

   other options
       -f device
	      Device of the tape archive (default is /dev/nst0).  Must be a character special file connected to a dds tape device.

       -V,--version
	      Print the version number of mt-dds to stderr and exit immediately.

       --help print some screens of online help with examples through a pager and exit immediately.

EXAMPLES

       Example 1: checking the compression mode of the default tape device
		 mt-dds comp-query

       Example 2: Write the location information as dds2tar command line options to stdout.
		 mt-dds

ENVIRONMENT

       The environment variable TAPE overrides the default tape device /dev/nst0.

       PAGER  The environment variable PAGER overrides the builtin pager command ("/bin/more") to display the output of the --help option.

SEE ALSO

       dds2tar(1), dds2index(1), mt(1), tar(1)

HISTORY

       This program was created to use it in conjunction with dds2tar.

AUTHOR

       J"org Weule (weule@cs.uni-duesseldorf.de), Phone +49 211 751409.  This software is available at ftp.uni-duesseldorf.de:/pub/unix/apollo

									2.4								 mt-dds(1)