mtdean at thirdcontact
Dec 16, 2008, 1:35 PM
Post #6 of 6
(5432 views)
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On 12/16/2008 03:52 PM, John Baab wrote:
> Keep in mind there are 2 different versions, ddrescue and gddrescue.
> I recommend gddrescue as it incorporates things like resuming from the
> log and some other features.
Actually, the names of the applications are dd_rescue (the original) and
ddrescue (which is a GNU app that does far more).
dd_rescue ( http://www.garloff.de/kurt/linux/ddrescue/ ) is very basic
and requires a lot of understanding to use. Therefore, LAB Valentin
wrote a script called dd_rhelp (
http://www.kalysto.org/utilities/dd_rhelp/index.en.html ) to make using
dd_rescue easier (and so that it generally does the right thing by
default). The dd_rhelp script added capabilities like automatically
skipping bad sectors to get all the good data first (then going back to
the bad sectors) as well as resuming and showing progress. However, LAB
Valentin said that the main problem with dd_rhelp was that it was a
shell script, rather than a C executable (like dd_rescue), so a better
solution was to incorporate the functionality provided by dd_rhelp into
dd_rescue.
Before he could do so, GNU decided they needed a tool like dd_rescue
(though both dd_rescue and dd_rhelp are GPL-licensed, GNU wanted a tool
that was part of the GNU project), so Antonio Diaz wrote one called
ddrescue ( http://www.gnu.org/software/ddrescue/ddrescue.html ). It
incorporates all the functionality provided by both dd_rescue and
dd_rhelp; therefore, it basically obsoletes the originals (and, the only
reason I can think of to choose to use the originals would be if some
sys admin had written a large script that uses dd_rescue/dd_rhelp and
he/she didn't feel like updating it/learning the new, improved approach).
For some reason, however, distros/packagers have decided that dd_rescue
and ddrescue are indistinguishable (whether that's due to limitations of
the package manager or the users, I couldn't say). So, to make things
better for "everyone" many (most?) have decided to rename the package
ddrescue to gddrescue (for "GNU ddrescue").
This, of course, makes sense... Rather than simply remove from all
repos the obsoleted tool dd_rescue (where even the author of dd_rhelp
says not to use dd_rhelp and dd_rescue but to use ddrescue, instead) or
rename the obsoleted tool, they renamed the good tool that should remain
in use indefinitely. Therefore, people tell other people to use a
non-existent program called gddrescue, which is just a renamed version
of ddrescue. So, people who use different distros (if any distro
actually did things right) or who want to find the upstream source are
very confused.
Anyway, gddrescue is likely a package name, but note that it should
contain the GNU program called ddrescue (which may be in the form of a
binary/executable called gddrescue). And, only dd_rescue (with an
underscore) is the one to avoid. The program ddrescue /should/ be the
good one.
However, I'll admit it's possible that packagers had decided to rename
dd_rescue to ddrescue before ddrescue was created, which would then mean
they'd need to rename ddrescue to gddrescue--unless, of course, they
just re-renamed dd_rescue (which was formerly ddrescue) to
obsoleteddrescue or whatever).
Mike "And some people think GNU/Linux is confusing?" Dean
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