Creating a custom data image / userdata.img for Android

This is a small description / tutorial on how to create a custom data image for flashing along with Android files. This is usually done to preload settings (if you created one e.g. from Customizing / Changing Android DPI settings or would like to load other data related files / information)

Get the required tools:

• Linux (easiest, if not get the necessary tools for Windows)
• simg2img (from, e.g. https://github.com/anestisb/android-simg2img)

Create an ext4 img file (in the example ~10GB)

dd if=/dev/zero of=data.img bs=1M count=10240
mkfs.ext4 data.img

Populate the data (sudo might be required)

mount -o loop data1.img mnt
// copy files to mnt
umount mnt 

Convert to simg

img2simg data.img userdata.img

You can now use userdata.img to flash with fastboot and other flashers/installers.