ddrescue Package Description

Like dd, dd_rescue does copy data from one file or block device to another. You can specify file positions (called seek and Skip in dd). There are several differences:

  • dd_rescue does not provide character conversions.
  • The command syntax is different. Call dd_rescue -h.
  • dd_rescue does not abort on errors on the input file, unless you specify a maximum error number. Then dd_rescue will abort when this number is reached.
  • dd_rescue does not truncate the output file, unless asked to.
  • You can tell dd_rescue to start from the end of a file and move backwards.
  • It uses two block sizes, a large (soft) block size and a small (hard) block size. In case of errors, the size falls back to the small one and is promoted again after a while without errors.

Source: http://www.garloff.de/kurt/linux/ddrescue/
ddrescue Homepage | Kali ddrescue Repo

  • Author: garloff
  • License: GPLv2

Tools included in the ddrescue package

dd_rescue – Copy data from one file or block device to another
root@kali:~# dd_rescue -h

dd_rescue Version 1.28, garloff@suse.de, GNU GPL
 ($Id: dd_rescue.c,v 1.130 2012/05/19 20:46:14 garloff Exp $)
 (compiled Dec 15 2012 12:04:22 by gcc (Debian 4.7.2-4) 4.7.2)
 (features: O_DIRECT splice )
dd_rescue copies data from one file (or block device) to another.
USAGE: dd_rescue [options] infile outfile
Options: -s ipos    start position in  input file (default=0),
         -S opos    start position in output file (def=ipos),
         -b softbs  block size for copy operation (def=65536, 1048576 for -d),
         -B hardbs  fallback block size in case of errs (def=4096, 512 for -d),
         -e maxerr  exit after maxerr errors (def=0=infinite),
         -m maxxfer maximum amount of data to be transfered (def=0=inf),
         -y syncfrq frequency of fsync calls on outfile (def=512*softbs),
         -l logfile name of a file to log errors and summary to (def=""),
         -o bbfile  name of a file to log bad blocks numbers (def=""),
         -r         reverse direction copy (def=forward),
         -t         truncate output file (def=no),
         -d/D       use O_DIRECT for input/output (def=no),
         -k         use efficient in-kernel zerocopy splice
         -w         abort on Write errors (def=no),
         -a         spArse file writing (def=no),
         -A         Always write blocks, zeroed if err (def=no),
         -i         interactive: ask before overwriting data (def=no),
         -f         force: skip some sanity checks (def=no),
         -p         preserve: preserve ownership / perms (def=no),
         -q         quiet operation,
         -v         verbose operation,
         -V         display version and exit,
         -h         display this help and exit.
Sizes may be given in units b(=512), k(=1024), M(=1024^2) or G(1024^3) bytes
This program is useful to rescue data in case of I/O errors, because
 it does not necessarily abort or truncate the output.

dd_rescue Usage Example

Start at position 100 of the input file (-s 100 /var/log/messages) and write, beginning at position 0 of the destination file (-S 0 /tmp/ddrescue-out):

root@kali:~# dd_rescue -s 100 /var/log/messages -S 0 /tmp/ddrescue-out
dd_rescue: (info): Using softbs=65536, hardbs=4096
dd_rescue: (info) expect to copy 1766kB from /var/log/messages
dd_rescue: (info): ipos:      1024.1k, opos:      1024.0k, xferd:      1024.0k
                   errs:      0, errxfer:         0.0k, succxfer:      1024.0k
             +curr.rate:  1122807kB/s, avg.rate:  1018906kB/s, avg.load:  0.0%
             >.......................-.................<  57%  ETA:  0:00:00
dd_rescue: (info): read /var/log/messages (1767.0k): EOF
dd_rescue: (info): Summary for /var/log/messages -> /tmp/ddrescue-out:
dd_rescue: (info): ipos:      1767.0k, opos:      1767.0k, xferd:      1767.0k
                   errs:      0, errxfer:         0.0k, succxfer:      1767.0k
             +curr.rate:   352945kB/s, avg.rate:   568151kB/s, avg.load:  0.0%
             >.......................-................-< 100%  ETA:  0:00:00