Usage: ddrescue [options] infile outfile [logfile]
You should use a logfile unless you know what you are doing.

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-split, non-trimmed blocks as non-tried
  -b, --block-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            do not read new data beyond logfile limits
  -d, --direct                   use direct disc access for input file
  -D, --synchronous              use synchronous writes for output file
  -e, --max-errors=[+]<n>        maximum number of [new] error areas allowed
  -E, --max-error-rate=<bytes>   maximum allowed rate of read errors per second
  -f, --force                    overwrite output device or partition
  -F, --fill=<types>             fill given type blocks with infile data (?*/-+)
  -g, --generate-logfile         generate approximate logfile from partial copy
  -i, --input-position=<bytes>   starting position in input file [0]
  -I, --verify-input-size        verify input file size with size in logfile
  -K, --skip-size=<bytes>        initial size to skip on read error [64 KiB]
  -m, --domain-logfile=<file>    restrict domain to finished blocks in file
  -M, --retrim                   mark all failed blocks as non-trimmed
  -n, --no-split                 do not try to split or retry failed blocks
  -o, --output-position=<bytes>  starting position in output file [ipos]
  -p, --preallocate              preallocate space on disc for output file
  -q, --quiet                    suppress all messages
  -r, --max-retries=<n>          exit after given retries (-1=infinity) [0]
  -R, --reverse                  reverse direction of copy operations
  -s, --max-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
  -v, --verbose                  be verbose (a 2nd -v gives more)
  -x, --extend-outfile=<bytes>   extend outfile size to be at least this long
Numbers may be followed by a multiplier: b = blocks, k = kB = 10^3 = 1000,
Ki = KiB = 2^10 = 1024, M = 10^6, Mi = 2^20, G = 10^9, Gi = 2^30, etc...
Time intervals have the format 1[.5][smhd] or 1/2[smhd].
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