I need to install Debian 10 from a USB stick (new computer doesn't have a CD/DVD drive). I'm in a neighbor machine with an Ubuntu 18 derivative. The Debian installation manual says:

The CD or DVD image you choose should be written directly to the USB stick, overwriting its current contents. For example, when using an existing GNU/Linux system, the CD or DVD image file can be written to a USB stick as follows, after having made sure that the stick is unmounted:

cp debian.iso /dev/sdX


The image must be written to the whole-disk device and not a partition, e.g. /dev/sdb and not /dev/sdb1. Do not use tools like unetbootin which alter the image.

1) It tells me to unmount the disk before copying.

2) It tells me to copy to the device, not to any partition.

Of course, when I unmount the usb stick, /dev/sdb1 goes away, and all I have left is /dev/sdb. However, when I try

cp debian.iso /dev/sdb

I get an instant error

cp: não foi possível criar arquivo comum '/dev/sdb': Mídia não encontrada

Sorry, my system is in Brazilian Portuguese. The above sentence means

cp: could not create common file '/dev/sdb': Media not found

I have tried the following command

dd if=debian.iso of=/dev/sdb

but the usb stick wasn't recognized by the new PC (maybe UEFI problem?). (In both commands above, I've used the real filenames instead of debian.iso.)

I have searched for the hd-media/boot.img.gz file, but none exists (nor the directory hd-media, nor the boot.img.gz file, in neither debian-10.1.0-amd64-netinst.iso or debian-10.1.0-amd64-xfce-CD-1.iso distributions.

Am I doing something wrong? Or Debian manual has some mistakes?


Based on the "Media not found" message I think you may be ejecting the device rather than unmounting the filesystem.

Are you sure you're unmounting the filesystem (right) or ejecting the USB (wrong)?

  • Thank you! I was ejecting rather than unmounting. But when I finally unmounted, /dev/sdb1 didn't disappear. It was disappearing when I ejected. – Rodrigo Oct 8 at 20:25
  • 1
    @Rodrigo yeah, /dev/sdb1 should still be there after unmount (but not eject). As you observed. (I struck that sentence from roaima's answer) – derobert Oct 8 at 20:31

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