RaspberryPi - resize the main partition to fill the SD card if there is more than 1GiB of free space on reboot

resize.sh

#!/bin/bash

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

## resize the main partition to fill the SD card if there is more than 1GiB of free space

unused_space="$(parted /dev/mmcblk0 unit GiB print free | awk '/Free Space/{c++; sum += $3} END{print sum}' | awk '{print ($0>1)?1:0}')"

if (( $unused_space ))
    then
        if [ -f /root/scripts/resize.attempting ]
            then
                > /root/scripts/resize.FAILED
                exit
            else
                > /root/scripts/resize.attempting
                raspi-config --expand-rootfs
                reboot
        fi
    else
        rm -f /root/scripts/resize.attempting
fi