About "ERROR: must be *superuser* to COPY to or from a file"

Greetings,

I met a question about Copy. I tried to run :
copy test(studid) from '/myownDIR/a.txt';

But I got an error as the following:
ERROR: must be *superuser* to COPY to or from a file

May I know is it possible that instead of supervuser, regular users are
able to use COPY as well?

Thanks a lot and Good weekend,
Emi