How to automatically replace date string with m4?

[Peng Yu]

Hi,

I can use coreutils' date to generate a date with a date string as follows.

date -d yesterday
date -d tomorrow

I am not sure if similar things are available in m4. Or how such a
feature can be implemented in m4?

For example, I want to replace the string YESTERDAY (or any other date
string accepted by coreutils' date (but capitalized)) in the input to
m4 by the actual date of yesterday. Is there a way to do so?

-- 
Regards,
Peng