question about the Debian preloaded SD card

Here is a version of the instructions for using dd  to write the image file using Linux that I modified to include reading the image. Note that BSD uses a

different naming convention for block devices than Linux does but after substituting the BSD versions it should work. Also note that these image files

can be => 2 GB in size.

1.  Run df -h to see what devices are currently mounted

2.  If your computer has a slot for SD cards, insert the card. If not, insert the card

     into an SD card reader, then connect the reader to your computer.

3.  Run df -h again. The device that wasn't there last time is your SD card. The left

     column gives the device name of your SD card. It will be listed as something like

     "/dev/mmcblk0p1" or "/dev/sdd1". The last part ("p1" or "1" respectively) is the

     partition number, but you want to read and write to the whole SD card, not just one

     partition, so you need to remove that part from the name (getting for example

     "/dev/mmcblk0" or "/dev/sdd") as the device for the whole SD card. Note that the

     SD card can show up more than once in the output of df: in fact it will if you

     have previously written a Raspberry Pi image to this SD card, because the RPi SD

     images have more than one partition.

4.  Now that you've noted what the device name is, you need to unmount it so that files

     can't be read or written to the SD card while you are copying over the SD image.

     So run the command below, replacing "/dev/sdd1" with whatever your SD card's

     device name is (including the partition number)

      * umount /dev/sdd1

      * If your SD card shows up more than once in the output of df due to having

         multiple partitions on the SD card, you should unmount all of these partitions.

5.  In the terminal read the image to the card with this command, making sure you

     replace the input file if= argument "/dev/sdd" with the right device name and the

     output file of= argument with the path and name of your .img file. Make sure the

     device name is the name of the whole SD card as described above, not just a

     partition of it (for example, sdd, not sdds1 or sddp1, or mmcblk0 not mmcblk0p1)

      * dd bs=1M if=/dev/sdd of=RP_debian.img

      * Note that if you are not logged in as root you will need to prefix this with sudo

      * The dd command does not give any information of its progress and so may appear

         to have frozen. If your card reader has an LED it may blink during the read

         process, or you can run pkill -USR1 -n -x dd in another terminal (prefixed

         with sudo if you are not logged in as root).

6.  To write the image to the card use this command, making sure you replace the input

     file if= argument with the path and name of your .img file, and the "/dev/sdd" in the

     output file of= argument with the right device name (this is very important: you will lose

     all data on the hard drive on your computer if you get the wrong device name). Make

     sure the device name is the name of the whole SD card as described above, not just

     a partition of it (for example, sdd, not sdds1 or sddp1, or mmcblk0 not mmcblk0p1)

      * dd bs=1M if=RP_debian.img of=/dev/sdd

      * Note that if you are not logged in as root you will need to prefix this with sudo

      * The dd command does not give any information of its progress and so may appear

         to have frozen. It could take more than five minutes to finish writing to the

         card. If your card reader has an LED it may blink during the write process, or

         you can run pkill -USR1 -n -x dd in another terminal (prefixed with sudo if you

         are not logged in as root).

7.  As root run the command sync or if a normal user run sudo sync (this will ensure the

     write cache is flushed and that it is safe to unmount your SD card)

8.  Remove SD card from card reader, insert it in the Raspberry Pi, and have fun

Why do I use pkill? 

Should I use ps to monitor the progress?

Why do I use pkill? 

Should I use ps to monitor the progress?

Hi,

The use of dd is not as complicated as the instructions seem to indicate. It really boils down to this:

1) Make sure you know which device (in /dev directory) the SD card is before you read or write to it with

    dd. This is critical because dd will overwrite everything on the device you use.

2) Make sure the device is not mounted before you use dd.

3) Make sure you read/write the device itself, not a partition on the device.

4) dd will take several minutes to write a 2GB image to an SD card. I've never timed it but I'm fairly certain

     that it is somewhere between 5 and 10 minutes on a class 10 SD card. Other SD devices are slower

     than this so it will vary. Reading the image is much faster.

I have used this procedure to do exactly what you are trying to do several time with no problems. dd will

write a message to the console showing how many blocks were read or written when it finishes so you will

know when it is done. I have never needed to use pkill which is intended to be used if dd hangs up which

hasn't happened to me so far. You can monitor dd with ps but to do so you will either have to run dd in the

background (add an & at the end of the dd command), or open a different terminal for the ps command. If

you run dd in the background it will not write any messages to the console when finished.