Customize space for external HDD (Banner)

Hi all.
There is a way to customize the banner script to show the free space for an external USB device storage?


For example


It’s great when you have installed something like Pydio, Nextcloud, etc…


You can use the custom banner entry option and on the input field enter:
df -h --output=avail /dev/sdb1 | mawk ‘NR==2 {print $1}’

Thanks MichaIng!