mt-dds - tool to control a dds device.
mt-dds
comp-on|comp-off|comp-query|comp-log
mt-dds < tell|label > [ -b
# ]
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.
- 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.
- 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.
- -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.
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
The environment variable TAPE overrides the default tape
device /dev/nst0.
- The environment variable PAGER overrides the builtin pager command
("/bin/more") to display the output of the --help
option.
This program was created to use it in conjunction with
dds2tar.
J"org Weule (weule@cs.uni-duesseldorf.de), Phone +49 211
751409. This software is available at
ftp.uni-duesseldorf.de:/pub/unix/apollo