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Re: Is there a way to install Debian iso's from an existing installation onto a USB connected drive?

On Thu 02 May 2019 at 15:12:46 +0200, Jonas Smedegaard wrote:

> Quoting Albretch Mueller (2019-05-02 14:42:08)
> >  something like:
> > 
> >  1) download the iso's
> > 
> >  2) go: <some application> /dev/sdb
> > 
> >  where "/dev/sdb" is the device a USB disk is linked to
> > 
> >  then you would plug the disk on your computer and take it from there
> > 
> >  For that I used to burn live DVD but there should be a better way
> Debian ISOs specifically are prepared to be used not only on optical 
> drives but also booted from e.g. USB flash drives.
> So "the better way" is to simply copy the image onto the device:
>   sudo cp downloaded_image /dev/sdb
I use cat downloaded_image > /dev/sdb

> There is a cargo cult preaching the use of "dd" but that tool is like 
> cutting trees with scissors: The wrong tool for the job!
> There are some suggesting to avoid the need for sudo by messing with 
> udev rules to grant non-root write access to removable devices.  When 
> properly established that is indeed more safe, but setting it up can go 
> wrong in just as bad and more complex ways to decipher than simply 
> mistyping the device name and wiping your main system drive.

This is along the same lines as Message #34 at


  > To random people reading this bug: please do not EVER do
  > this or it may subtly break other things and then get you
  > flamed when you will waste my time debugging that.

Although the issue is treated sympathetically towards the end of the
report, I don't believe I've ever seen an example of subtle breakage.

I agree with what is said in Message #23 at


  > In any case, it seems unfortunate that users can no
  > longer write an image to a USB disk without using root.
  > Especially because that makes it easier to make a mistake
  > and overwrite the wrong disk. I've made ahabit of always
  > dd'ing as non-root, to make it somewhat less likely that
  > I'd overwrite a system disk.

Which is why I have a udev rule with

  SUBSYSTEM=="block", ATTRS{removable}=="1", GROUP="floppy"

in it. I might stop doing that if its use was demonstrated to have an
adverse effect on other things I do.