Hello bill.yu,
Tried to follow the instructions you provided at <LINK_TEXT text=“https://project.seeedstudio.com/SeeedSt … -pi-3e100f”>https://project.seeedstudio.com/SeeedStudio/face-count-and-display-using-grove-ai-hat-and-pi-3e100f</LINK_TEXT>
No luck! The install did not do anything and here the output for the second variation you suggested:
</s>$ sudo ./face-detected.sh
Segmentation fault
$ <e>
Anything else that I could be checking or testing or installing? I would like to put the AI HAT to some use. 
Kind regards.