Writing the value of DateModified to EXIF DateTaken for a batch of files

[yuri.feigin]

Dear Fellows,
Does anybody can help to find a simple solution to replace the EXIF DateTaken  value with DateModified into value for a batch of files?

The reason I need to do this, is because I'm trying to move WhatsApp media from one android device to another.
Since WhatsApp strips the EXIF, the Gallery android apps sort the files by date modified (when DateTaken is missing).
Copying from one adroid device to another changes the DateModified to the DateCreated.
So my idea is to copy the value of DateModified to DateTaken before copying the files to other device.
Doing it manually for one file is easy,
but how to do it for a batch?

Thank You.

[Phil Harvey]

I assume you mean something like this:

exiftool "-datetimeoriginal<filemodifydate" DIR

- Phil