So I'm relatively comfortable using *dd* on a linux system to copy the
contents of an sd card to an image file. Previously I had run the command...
sudo dd status=progress bs=512 count=$((8192+6955008)) if=/dev/disk4 of=
... and that usually does the trick. However, I'm a bit confused because
the count value isn't lining up with the current card specs. I just created
a flasher on a 16GB card using the aforementioned script. But when I insert
that sd card to my development laptop and I run...
sudo fdisk -l /dev/sdb
... I get the following output:
$ sudo fdisk -l /dev/sdb
[sudo] password for troyw:
Disk /dev/sdb: 14.9 GiB, 15931539456 bytes, 31116288 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x55866915
Device Boot Start End Sectors Size Id Type
/dev/sdb1 * 8192 31116287 31108096 14.9G 83 Linux
My confusion is that I recall the card should be 8192+6955008 sectors long,
not 31116287 sectors long... So what happened? Did something change
recently in the aforementioned flasher-making script? Does it now
automatically expand to the sd card size? Do I need to re-partition the
*/dev/sdb* device and *then* use the *dd* command? How would I determine
how much I can shrink the partition without losing the data on the image?
Any help would be greatly appreciated.
On Monday, February 5, 2018 at 7:17:17 AM UTC-8, Dennis Lee Bieber wrote:
> On Mon, 5 Feb 2018 04:41:12 -0800 (PST),
> >My problem is that I would like to save the images that were created in
> >SD card in the PC, in order to have several releases saved. When I insert
> >the SD card into the PC, I try to open it to make a copy of the image, I
> >get a message saying that it can not be opened and also asks if I want to
> >format the SD card.
> M$ Windows OS?
> >Someone could help me to know how I can copy those images to my PC to
> The (apparently deprecated) Win32DiskImager program appears to
> have the
> ability to move in both directions -- so can generate an image file by
> reading an SD card (Etcher appears to only support writing an image file
> SD card).
> However, as I recall, it was rather sensitive to the card used --
> tried to duplicate a card (both nominally 8GB) but the target card
> brand) was just different enough that the image could not be written (I
> think the target card reserved more blocks for overhead, with the result
> the original image was now too large for the target).
> Wulfraed Dennis Lee Bieber AF6VN
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