linux-kernel - [question] What happens when dd writes data to a missing device?

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Message-ID: <CABXGCsOVXh89h2e4EuNbDKiCNwKm8599UE-h0GN-jPhpfyoCVA@mail.gmail.com>
Date:   Mon, 12 Oct 2020 00:46:03 +0500
From:   Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
To:     Linux List Kernel Mailing <linux-kernel@...r.kernel.org>
Subject: [question] What happens when dd writes data to a missing device?

Hi folks!
I have a question.
What happens when dd writes data to a missing device?

For example:
# dd if=/home/mikhail/Downloads/Fedora-Workstation-Live-x86_64-Rawhide-20201010.n.0.iso
of=/dev/adb

Today I and wrongly entered /dev/adb instead of /dev/sdb,
and what my surprise was when the data began to be written to the
/dev/adb device without errors.

But my surprise was even greater when cat /dev/adb started to display
the written data.

I have a question:
Where the data was written and could it damage the stored data in
memory or on disk?

--
Best Regards,
Mike Gavrilov.