Shrink system image on Linux

shrink-image-linux.txt

# Link https://github.com/Adriangarridosanchis/SensorNetwork./wiki/Shrink-system-image-on-Linux

Shrink system image on Linux
benchchair edited this page on 8 Jul 2014 · 16 revisions
Why
The image extracted from a finalized SD card is slightly larger than the capacity of SD card. We need to shrink the size of image so that we can always copy the image into the same capacity SD card or even a smaller one.

# Requirements
A Linux PC or a Linux virtual machine (Virtual machine software: Virtual Box or VMware)
Steps

1 - Creating loopback device
$ sudo modprobe loop
$ sudo losetup -f (Example: /dev/loop0)
$ sudo losetup /dev/loop0 myimage.img
$ sudo partprobe /dev/loop0

2 - Resize partition using GParted
$ sudo gparted /dev/loop0
- Resize the image in the pop-up GParted App.
- Press Apply in GParted.
$ sudo losetup -d /dev/loop0

3 - Shaving the image
$ fdisk -l myimage.img image
$ truncate --size=$[(<Device Boot End>+1)*<IO size bytes>] myimage.img
- Example
$ truncate --size=$[(9181183+1)*512] myimage.img