Changes from 1.12:
The current version is 1.14, released 2007-08-28.
In version 1.14, a bug is fixed that could lead to a target file not having the
correct size when copied in sparse (-a) mode.
In version 1.13, a bug with read-errors and non-seekable output has been fixed.
In version 1.12, the ability to log bad blocks to a ASCII file has been added.
The option -y can be used to set the fsync frequency which can speed up the
copy significantly.
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.
