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Re: Partition information as text file?

From <tomas@tuxteam.de>
Newsgroups linux.debian.user
Subject Re: Partition information as text file?
Date 2019-01-30 17:00 +0100
Message-ID <xm0rn-17a-1@gated-at.bofh.it> (permalink)
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On Wed, Jan 30, 2019 at 09:07:37AM -0600, Richard Owlett wrote:

[...]

> The man pages for fdisk, parted, sfdisk, tune2fs, and dumpe2fs each
> give "device" as a possible parameter. Only the last two balk at it.

This is as if you said that a fillet knife and a nutcracker both
specify "food" as a possible parameter. But expect the cook to
kick you out of the kitchen if you try to crack a nut with the
fillet knife (although you might succeed at it).

As a toolsguy this should be familiar to you.

The last two expect a "device" (which is just a kind of file, you
can do all of that with a bog standard file, everything which can
be seen as a long series of blocks is fair game) _containing_ an
ext2 file system (actually they most probably look first at the
header to check this).

 - (block) device file: (e.g. /dev/sdb)
   a contraption of your operating system making a storage
   device available as a file of sorts, to ease the lives
   of many utilities

 - partition: a part of a block device. Usually (you don't
   _have_ to), a storage device is subdivided into several
   partitions. This subdivision is documented in the
   partition table (which can be the oldskool DOS partition
   table with the well-known limitations of 4 viz. 3+4
   partitions or a more modern GPT or some others living
   out there). Usually this partition table is written as
   a data structure somewhere at the start of the storage
   device (and thus at the first block(s) of the device
   file).

   A partition is usually made available as a device file
   too (e.g. /dev/sdb1)

   A plain regular file can be made available as a device
   via the loopback driver (this is useful for virtual
   machines, but also for experiments -- e.g. I work on
   a file "image" for my Raspi which I can mount and
   look into with my laptop. When I'm happy I just dump
   it to an SD card.

 - file system: the whole machinery needed to organize your
   data whithin a huge unstructured pool of blocks. There
   are many constraints on a file system, like efficient
   space usage, quick allocation of new files, contiguous
   allocation of space (whenever possible) for a file (this
   is most important for mechanical drives), etc.

   There are many different file systems, in response to
   many different requirements and historical roots.

   You typically "put" a file system on a device file (the
   storage behind that is the "backend"), be it a device,
   a partition, a logical volume or a loopback on a
   regular file: the file system code doesn't care, as
   long as it sees a long, boring array of blocks, all
   alike.

Clearer now?

Cheers
-- t

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Thread

Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-26 15:40 +0100
  Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-01-26 18:10 +0100
  Re: Partition information as text file? Felix Miata <mrmazda@earthlink.net> - 2019-01-26 20:40 +0100
    Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-26 22:20 +0100
      Re: Partition information as text file? "Alexander V. Makartsev" <avbetev@gmail.com> - 2019-01-26 23:00 +0100
      Re: Partition information as text file? Felix Miata <mrmazda@earthlink.net> - 2019-01-27 03:10 +0100
      Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-01-27 22:30 +0100
        Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-28 13:50 +0100
          Re: Partition information as text file? Ionel Mugurel Ciobîcă <I.M.Ciobica@gmail.com> - 2019-01-28 16:50 +0100
          Re: Partition information as text file? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-01-28 20:50 +0100
            Re: Partition information as text file? <tomas@tuxteam.de> - 2019-01-29 15:40 +0100
              Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-29 16:30 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-01-29 16:40 +0100
                Re: Partition information as text file? "Thomas Schmitt" <scdbackup@gmx.net> - 2019-01-29 17:20 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-31 15:20 +0100
                Re: Partition information as text file? "Thomas Schmitt" <scdbackup@gmx.net> - 2019-01-31 16:00 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-01-31 20:30 +0100
                Re: Partition information as text file? "Thomas Schmitt" <scdbackup@gmx.net> - 2019-01-31 21:10 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-02-01 15:10 +0100
                Re: Partition information as text file? "Thomas Schmitt" <scdbackup@gmx.net> - 2019-02-01 15:30 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-02-01 16:10 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-02-01 16:30 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-01 17:10 +0100
                Re: Partition information as text file? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-02-01 19:40 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-02-01 22:30 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-01 17:20 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-02-01 18:10 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-02 02:10 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-02-02 11:00 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-02 16:30 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-02-02 17:20 +0100
                Re: Partition information as text file? rhkramer@gmail.com - 2019-02-01 17:00 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-01 17:10 +0100
                Re: Partition information as text file? Felix Miata <mrmazda@earthlink.net> - 2019-02-01 17:20 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-01 17:30 +0100
                Re: Partition information as text file? Joe <joe@jretrading.com> - 2019-02-01 19:10 +0100
                Re: Partition information as text file? Greg Wooledge <wooledg@eeg.ccf.org> - 2019-02-01 19:20 +0100
                Re: Partition information as text file? Dan Ritter <dsr@randomstring.org> - 2019-02-01 19:30 +0100
                Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-02-01 23:10 +0100
                Re: Partition information as text file? Peter Ehlert <peter@sdi-baja.com> - 2019-01-29 17:40 +0100
                Re: Partition information as text file? Jude DaShiell <jdashiel@panix.com> - 2019-01-29 19:00 +0100
            Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-29 15:40 +0100
              Re: Partition information as text file? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-01-29 21:10 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-30 16:10 +0100
                Re: Partition information as text file? <tomas@tuxteam.de> - 2019-01-30 17:00 +0100
                Talking about loop devices (was: Re: Partition information as text file?) David <bouncingcats@gmail.com> - 2019-01-31 02:20 +0100
                Re: Talking about loop devices (was: Re: Partition information as  text file?) David <bouncingcats@gmail.com> - 2019-01-31 04:50 +0100
                Re: Talking about loop devices (was: Re: Partition information as  text file?) <tomas@tuxteam.de> - 2019-01-31 10:10 +0100
                Re: Talking about loop devices Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-01-31 20:00 +0100
                Re: Talking about loop devices David <bouncingcats@gmail.com> - 2019-02-01 06:30 +0100
                Re: Partition information as text file? Joe <joe@jretrading.com> - 2019-01-30 17:10 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-31 15:30 +0100
                Re: Partition information as text file? Pascal Hambourg <pascal@plouf.fr.eu.org> - 2019-01-30 19:50 +0100
              Re: Partition information as text file? David <bouncingcats@gmail.com> - 2019-01-30 03:10 +0100
                Re: Partition information as text file? Richard Owlett <rowlett@cloud85.net> - 2019-01-30 16:20 +0100
          Re: Partition information as text file? David Wright <deblis@lionunicorn.co.uk> - 2019-01-29 19:30 +0100

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