On a sunny day (Sat, 04 Aug 2018 11:21:00 +1200) it happened
nospam.Henri.Derksen@f1208.n280.z2.binkp.net (Henri Derksen) wrote in
:

>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.

Yes, I have the old Unix habit of typing 'sync' 3 times every now and then.

An other thing I notice with my USB sticks is that even after copy and sync the
LED on the USB stick keeps flashing,
sometimes for up to a minute or so.
I once asked in a Linux group if it was safe to remove the USB stick when that
LED was still flashing
and was told that was OK...
Nevertheless I always wait until it is off.
For SDcards it is hard to tell, no LED, but I think the internal controller on
the cards / sticks does some housekeeping
even after the copy has finished.
So maybe it is better to leave it in for a minute or so longer.


>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 ;-)

I always type
dmesg
then insert the new card, and type dmesg again.
The new card should be mentioned in the last report.

Before inserting SDcard (here on the PC for demo):
~# dmesg
3277686.710313] sd 111:0:0:3: Attached scsi generic sg6 type 0
[3277686.710639] sd 111:0:0:1: [sdd] Attached SCSI removable disk
[3277686.713316] sd 111:0:0:2: [sde] Attached SCSI removable disk
[3277686.714815] sd 111:0:0:3: [sdf] Attached SCSI removable disk

After inserting SDcard
~# dmesg
[3277710.813919] sd 114:0:0:0: [sdc] 7733248 512-byte logical blocks: (3.95
GB/3.68 GiB)
[3277710.823929] sd 114:0:0:2: [sde] Attached SCSI removable disk
[3277710.863908] sd 114:0:0:0: [sdc] Write Protect is off
[3277710.863912] sd 114:0:0:0: [sdc] Mode Sense: 03 00 00 00
[3277710.863915] sd 114:0:0:0: [sdc] Assuming drive cache: write through
[3277710.983879] sd 114:0:0:3: [sdf] Attached SCSI removable disk
[3277710.995120] sd 114:0:0:0: [sdc] Assuming drive cache: write through
[3277711.012886]  sdc: sdc1
[3277711.042892] sd 114:0:0:0: [sdc] Assuming drive cache: write through
[3277711.042900] sd 114:0:0:0: [sdc] Attached SCSI removable disk

So the card is /dev/sdc,
and it has partition sdc1 and is a 4 GB card (from my Canon camera in this
demo),
and has 512 bytes / sector.


What is mounted you can find by typing
mount
If I then do
mount /dev/sdc1 /mnt/sdc1
and type mount again, then I should see it listed

You can also type
df
to see what is mounted and how much space you have.


>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.

Thank you for the invitation, I appreciate it
Greetings
Jan

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