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

Packages and Binaries:

ddrescue

When your disk has crashed and you try to copy it over to another one, standard Unix tools like cp, cat, and dd will abort on every I/O error, dd_rescue does not. It optimizes copying by using large blocks as long as no errors occur and falls back to smaller blocks. It supports reverse direction copying (to approach a bad spot from the top), sparse copying, preallocating space, splice zerocopy, and bypassing the kernel pagecache with O_DIRECT. dd_rescue provides safe deletion of data by overwriting files (or better partitions/disks) multiple times with fast random numbers. With the ddr_hash plugin, it supports calculating a hash value (such as a sha256sum) or an HMAC during copying.

Installed size: 407 KB
How to install: sudo apt install ddrescue

  • libc6
  • liblzo2-2
  • libssl1.1
dd_rescue

Data recovery and protection tool

root@kali:~# dd_rescue -h

dd_rescue Version 1.99.11, kurt@garloff.de, GNU GPL v2/v3
 (DD_RESCUE_1_99_11-7-gc263a59)
 (compiled Jun 17 2021 09:19:26 by gcc (Debian 10.2.1-6) 10.2.1 20210110)
 (features: O_DIRECT dl/libfallocate fallocate splice fitrim xattr rdrnd avx2)
dd_rescue is free software. It's protected by the terms of GNU GPL v2 or v3
 (at your option).
dd_rescue copies data from one file (or device or pipe) to others.
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=131072, 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 transferred (def=0=inf),
         -M         avoid extending outfile,
         -x         count opos from the end of outfile (eXtend),
         -y syncsz  frequency of fsync calls in bytes (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),
         -R         repeatedly write same block (def if infile is /dev/zero),
         -t         truncate output file at start (def=no),
         -T         truncate output file at last pos (def=no),
         -u         undo writes by deleting outfile and issuing fstrim
         -d/D       use O_DIRECT for input/output (def=no),
         -k         use efficient in-kernel zerocopy splice,
         -P         use fallocate to preallocate target space,
         -L plug1[=par1[:par2]][,plug2[,..]]    load plugins,
         -w         abort on Write errors (def=no),
         -W         read target block and avoid Writes if identical (def=no),
         -a         detect zero-filled blocks and write spArsely (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, times, attrs (def=no),
         -C limit   rateControl: avoid xfer data faster than limit B/s
         -Y oname   Secondary output file (multiple possible),
         -F off[-off]r/rep[,off[-off]w/rep[,...]]  fault injection (hardbs off) r/w
         -q         quiet operation,
         -v         verbose operation,
         -c 0/1     switch off/on colors (def=auto),
         -V         display version and exit,
         -h         display this help and exit.
Instead of infile, -z/Z SEED or -z/Z SEEDFILE may be specified, taking the PRNG
 from libc or frandom (RC4 based) as input. SEED = 0 means a time based seed;
 Using /dev/urandom as SEEDFILE gives good pseudo random numbers.
Likewise, -3 SEED/SEEDFILE will overwrite ofile 3 times (r,ir,0, BSI M7.15).
 With -4 SEED/SEEDFILE you get an additional random pass (r,ir,r2,0).
 With -2 SEED/SEEDFILE you only get one random pass (r,0).

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 normally abort or truncate the output.
It may also help data protection by securely overwriting data.
There are plugins for compression, hashing and encryption.
Have a look a the man page for more details and long options.

Updated on: 2021-Nov-26