Hello Jan,

I wrote to you:

JP>> The other problem you then have is that you cannot run a verify.
JP>> diff myimage /dev/sd?

HD> Until now I never did.
HD> I just tried if the copy works well.
HD> But indeed shut down the source card, and making a backup of it when it
HD> not runs is the best procedure.

A friend of my at the Dutch RISC OS Big Ben Computer club in Drachten.NL,
and lives in Groningen.NL,
told me in october 2016 to use the following syntax:
sudo dd if=jessie.img of=/dev/sda bs=4M
And he said that it is very important to use:
sync
after the copy with the dd command has finished.
That "sync" writes the last bytes from the buffer to the destination SDcard.
After that you can verify its contents if the copy did succeed properly.

My friend also suggests to use the command df for finding the right devices.
But I have remarked that it only works for mounted devices, not the unmounted
SDcard reader/writers, emty or not.
If a SDcard has the same UUID as the one booted from, it will NOT be mounted
since Raspbian Stretch ;-(.
Of course there is a command to find out witch devices are connected.
Now I have to find out that ;-)
Until now I used the internal SDcopier util for it.
But there is a better way for sure.

I think it is a good idea to create a 16 GB stretch.img at a 64 GB card
or USB stick after I am ready configuring this new card.

If you have time also try to come to our computerclub in Drachten.nl
every 3rd Thursday of every month, except July and August.
So at the 20 th of September 2018 after 19:30 h, we are coming together again,
and also all the next months.
Normally I am not the most early bird that evenings ;-).
But I am there until the end at 23:00 h.
Ask for the adres by private (e-)mail.
You can also find it at the website .

Henri.

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