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Re: Is there a good "dd for dummies" tutorial around?

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On 2016-02-22 02:59, Carlos E. R. wrote:
> On 2016-02-20 19:04, pureheart@pacbell.net wrote:
>> This is probably considered basic stuff but I'm still having trouble understanding dd.
>>
>> In particular, why do the things it writes/reads to have to be *un*mounted?
> 
> They don't. It depends on what you want to do.

To clarify.

 dd if=/tmp/somefile of=/tmp/someotherfile

needs the filesystem be mounted. while:

 dd if=/dev/sdb1 of=/tmp/imageofsdb1

can run while sdb1 is mounted, but the resulting image will be "dirty";
ie, it will at need an fsck before being used. And if something changes
in the mounted sdb1 while the copy runs, the resulting image will be
inconsistent.

This one:

 dd if=/tmp/imageofsdb1 of=/dev/sdb1

might (at worst) provoke a crash of some kind if sdb1 is mounted while
you write to it this way.


None of that is specific to 'dd', but to copy and filesystem operations,
regardless of whatever tool you use.

In fact, all those operations can be done with a plain "cp", ie, the
copy file program.

-- 
Cheers, Carlos.

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Is there a good "dd for dummies" tutorial around? pureheart@pacbell.net - 2016-02-20 10:04 -0800
  Re: Is there a good "dd for dummies" tutorial around? Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2016-02-20 20:24 +0200
  Re: Is there a good "dd for dummies" tutorial around? William Unruh <unruh@invalid.ca> - 2016-02-20 18:26 +0000
  Re: Is there a good "dd for dummies" tutorial around? Robert Heller <heller@deepsoft.com> - 2016-02-20 12:40 -0600
  Re: Is there a good "dd for dummies" tutorial around? Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2016-02-20 14:10 -0500
  Re: Is there a good "dd for dummies" tutorial around? "Carlos E. R." <robin_listas@invalid.es> - 2016-02-22 02:59 +0100
    Re: Is there a good "dd for dummies" tutorial around? "Carlos E.R." <robin_listas@invalid.es> - 2016-02-22 04:39 +0100
      Re: Is there a good "dd for dummies" tutorial around? pureheart@pacbell.net - 2016-02-24 15:55 -0800
        Re: Is there a good "dd for dummies" tutorial around? "Carlos E. R." <robin_listas@invalid.es> - 2016-02-26 03:39 +0100
          Re: Is there a good "dd for dummies" tutorial around? pureheart@pacbell.net - 2016-02-29 18:05 -0800
            Re: Is there a good "dd for dummies" tutorial around? The Natural Philosopher <tnp@invalid.invalid> - 2016-03-01 02:45 +0000
            Re: Is there a good "dd for dummies" tutorial around? "Carlos E.R." <robin_listas@invalid.es> - 2016-03-01 11:14 +0100

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