Resize image file before writing to SD card

Question

I've been trying to create a new Raspbian image with a different kernel (with CAN support) and with Python 3.3 installed. Rather than doing all of this on the Raspberry Pi, I thought it would be interesting to do it on the computer instead (following these instructions). However, once I'd got the image mounted and ready to go, I quickly ran out of disk space. I presume this is because the image is sized to be only just big enough with the expectation that the user will resize the file-system once it has been written to an SD card.

Is it possible to resize the image and file-system before writing it to the SD card so that I can do more customisation without running out of space?

Answer 1

This is how to resize a raw image file. I know it sounds stupidly simplistic, but it will work.

Create a blank image, of the size you want to expand the original (in my example I use 5GB);

dd if=/dev/zero of=/path/to/temp_image bs=1 count=1 seek=5G

Append this to the original image:

cat /path/to/temp_image >> /path/to/rasperrypi.img

Resize the filesystem that lives at the end of the disk (usually this is the one you want bigger):

resize2fs -f /path/to/rasperrypi.img

Done! Your disk should now be 5GB bigger!