dd

Tips and Tricks

The dd command is used to prepare microSD card like this:

frank@FrankBuntuSSD:~$ sudo dd if=path/to/some-image-raspberrypi3.rpi-sdimg of=/dev/sdX bs=4M iflag=fullblock oflag=direct conv=fsync status=progress

Expect a write speed of only 5 to 15 MB/s.

Older dd's do not understand status=progress. You can leave that out or try the following alternatives:

progress monitoring

Use the oflag=direct, otherwise dd writes everything quickly to a cache and the progress indication fools you.

modern dd version

add the status=progress flag.

kill trick

When dd receives a SIGUSR1 signal (sending requires sudo privileges!) it will respond with a progress message. This must be from the late 70ies...

fancy dance

use a pipe plus pv (progress viewer) and dialog: https://www.cyberciti.biz/faq/linux-unix-dd-command-show-progress-while-coping/

test if SD card can be (over)written

Replace sdX with the real device name, find it with lsusb, and fill it with random bytes:

sudo dd if=/dev/urandom of=/dev/sdX bs=1M oflag=direct,sync conv=fsync status=progress