Explorer/RaspberryPi/PowerOffProtection

• Install

git clone https://github.com/marklister/overlayRoot.git
cd overlayRoot 
sudo bash install

sudo dphys-swapfile swapoff;\
sudo dphys-swapfile uninstall;\
sudo update-rc.d dphys-swapfile remove

• Check

check: reboot, create file, reboot, file is not here

/boot/cmdline.txt
remove "init=/sbin/overlayRoot.sh"

check: reboot, create file, reboot, file is here

• Usage

sudo mount -o remount,rw /ro
sudo chroot /ro

• Add a writable data partition

Get and plug the RaspberryPi SD memory card on a desktop and create new FAT32 data partion.
Get and plug the SD memory card on the Raspbery Pi and boot.

check /etc/fstab
"
proc            /proc           proc    defaults          0       0
PARTUUID=738a4d67-01  /boot           vfat    defaults          0       2
PARTUUID=738a4d67-02  /               ext4    defaults,noatime  0       1
"
add new partition with yours UUID
PARTUUID=738a4d67-03  /data           vfat    nofail,umask=0000 0       0

See "usage" to update /etc/fstab on the "writable" partition