Warning: Error opening file -*, in Apple Automator

[DGMAC]

Following Agill's guide with a few tweaks for El Capitan I have the following Shell Script working in Automator, although it returns an error:

for f in "$@"
do
   /usr/local/bin/exiftool −r −overwrite_original -TagsFromFile @ '-Description<$XMP:Subject $FilePath' *, "$f"
done

The error reads: 'Warning:Error opening file - *,

The command is correctly recursively copying keyword and directory path metadata to the description field for all files in whatever folder I select (so it will be searchable in Google Photos), but I would like to stop getting the warning error when it is executed. Any help appreciated.

[StarGeek]

Sorry, I should have caught this before.  You can't use -r and a wildcard.  See Common Mistake 2c.  Just remove the *. 

[DGMAC]

Thanks, that did it.