ddrescue

DDRESCUE(1) User Commands DDRESCUE(1)

NAME

   ddrescue - data recovery tool

SYNOPSIS

   ddrescue [options] infile outfile [mapfile]

DESCRIPTION

   GNU ddrescue is a data recovery tool. It copies data from one file or block device (hard disc, cdrom, etc) to another, trying to rescue the good parts first in case of read errors.

   Always use a mapfile unless you know you won't need it. Without a mapfile, ddrescue can't resume a rescue, only reinitiate it. Be careful to not specify by mistake an old mapfile from
   an unrelated rescue.

   NOTE: In versions of ddrescue prior to 1.20 the mapfile was called 'logfile'. The format is the same; only the name has changed.

   If you reboot, check the device names before restarting ddrescue.  Don't use options '-F' or '-G' without reading the manual first.

OPTIONS

   -h, --help
          display this help and exit

   -V, --version
          output version information and exit

   -a, --min-read-rate=<bytes>
          minimum read rate of good areas in bytes/s

   -A, --try-again
          mark non-trimmed, non-scraped as non-tried

   -b, --sector-size=<bytes>
          sector size of input device [default 512]

   -B, --binary-prefixes
          show binary multipliers in numbers [SI]

   -c, --cluster-size=<sectors>
          sectors to copy at a time [128]

   -C, --complete-only
          don't read new data beyond mapfile limits

   -d, --idirect
          use direct disc access for input file

   -D, --odirect
          use direct disc access for output file

   -e, --max-bad-areas=[+]<n>
          maximum number of [new] bad areas allowed

   -E, --max-error-rate=<bytes>
          maximum allowed rate of read errors per second

   -f, --force
          overwrite output device or partition

   -F, --fill-mode=<types>
          fill blocks of given types with data (?*/-+l)

   -G, --generate-mode
          generate approximate mapfile from partial copy

   -H, --test-mode=<file>
          set map of good/bad blocks from given mapfile

   -i, --input-position=<bytes>
          starting position of domain in input file [0]

   -I, --check-input-size
          compare input file size with size in mapfile

   -J, --check-on-error
          reread latest good sector after every error

   -K, --skip-size=[<i>][,<max>]
          initial,maximum size to skip on read error

   -L, --loose-domain
          accept unordered domain mapfile with gaps

   -m, --domain-mapfile=<file>
          restrict domain to finished blocks in <file>

   -M, --retrim
          mark all failed blocks as non-trimmed

   -n, --no-scrape
          skip the scraping phase

   -N, --no-trim
          skip the trimming phase

   -o, --output-position=<bytes>
          starting position in output file [ipos]

   -O, --reopen-on-error
          reopen input file after every read error

   -p, --preallocate
          preallocate space on disc for output file

   -P, --data-preview[=<lines>]
          show some lines of the latest data read [3]

   -q, --quiet
          suppress all messages

   -r, --retry-passes=<n>
          exit after <n> retry passes (-1=infinity) [0]

   -R, --reverse
          reverse the direction of all passes

   -s, --size=<bytes>
          maximum size of input data to be copied

   -S, --sparse
          use sparse writes for output file

   -t, --truncate
          truncate output file to zero size

   -T, --timeout=<interval>
          maximum time since last successful read

   -u, --unidirectional
          run all passes in the same direction

   -v, --verbose
          be verbose (a 2nd -v gives more)

   -w, --ignore-write-errors
          make fill mode ignore write errors

   -W, --compare-before-write
          omit superfluous writes in rescue mode

   -x, --extend-outfile=<bytes>
          extend outfile size to be at least this long

   -X, --max-read-errors=<n>
          maximum number of read errors allowed

   -y, --synchronous
          use synchronous writes for output file

   -Z, --max-read-rate=<bytes>
          maximum read rate in bytes/s

   --ask  ask for confirmation before starting the copy

   --command-mode
          execute commands from standard input

   --continue-on-errno=<n>[,<n>]
          treat errno code <n> as non-fatal

   --cpass=<range>
          select what copying pass(es) to run

   --delay-slow=<interval>
          initial delay before checking slow reads [30]

   --log-events=<file>
          log significant events in <file>

   --log-rates=<file>
          log rates and error sizes in <file>

   --log-reads=<file>
          log all read operations in <file>

   --mapfile-interval=[i][,i]
          save/sync mapfile at given interval [auto]

   --max-slow-reads=<n>
          maximum number of slow reads allowed

   --pause-on-error=<interval>
          time to wait after each read error [0]

   --pause-on-pass=<interval>
          time to wait between passes [0]

   --reset-slow
          reset slow reads if rate rises above min

   --same-file
          allow infile and outfile to be the same file

   Numbers  may  be  in decimal, hexadecimal, or octal, and may be followed by a multiplier: s = sectors, k = 1000, Ki = 1024, M = 10^6, Mi = 2^20, etc...  Time intervals have the format
   1[.5][smhd] or 1/2[smhd].

   Exit status: 0 for a normal exit, 1 for environmental problems (file not found, invalid command-line options, I/O errors, etc), 2 to indicate a corrupt or invalid input file, 3 for an
   internal consistency error (e.g., bug) which caused ddrescue to panic.

REPORTING BUGS

   Report bugs to bug-ddrescue@gnu.org
   Ddrescue home page: http://www.gnu.org/software/ddrescue/ddrescue.html
   General help using GNU software: http://www.gnu.org/gethelp

COPYRIGHT

   Copyright © 2025 Antonio Diaz Diaz.  License GPLv2+: GNU GPL version 2 or later <http://gnu.org/licenses/gpl.html>
   This is free software: you are free to change and redistribute it.  There is NO WARRANTY, to the extent permitted by law.

SEE ALSO

   The full documentation for ddrescue is maintained as a Texinfo manual.  If the info and ddrescue programs are properly installed at your site, the command

          info ddrescue

   should give you access to the complete manual.

GNU ddrescue 1.29 January 2025 DDRESCUE(1)