multiple arg files and a custom namespace

[inanealex]

I have a file containing a list of custom namespace tags, and a second file containing a list of files, and hope to use something like the following script to write the results to a file.
I stared with:  exiftool -@ MD_Lookup.txt -@ MD_Files.txt >> results.txt and hilarity ensued when it threw the error: Ignored superfluous tag name or invalid option: -xmp-vcsPG:graphicType    Warning: No writable tags set from [filename from MD_Files.txt file].

"-xmp-vcsPG:graphicType" is the second line of the MD_Lookup.txt arg file.

So, I broke out the first two tags from the arg file, added them to the script: exiftool -xmp-vcsPG:graphicType -xmp-vcsPG:description -@ MD_Files.txt >> results.txt and it works as I expect, writing the filename and values of these two tags to a text file.

Then, to help my understanding, used the MD_Lookup.txt arg file against a single file: exiftool -@ MD_Lookup.txt sample_metadata.ai and got the same error as the first time: Ignored superfluous tag name or invalid option: -xmp-vcsPG:graphicType      0 image files updated   1 image files unchanged. I'm not surprised, but I don't understand.

My MD_Lookup.txt file has a dozen tags in it in the following format:
-xmp-vcsPG:graphicType
-xmp-vcsPG:description
-xmp-vcsPG:designer

I've seen other forum posts where this type of list is used to copy tag values from one file to another, but never writing the contents of a tag list to a file. Any recommendations?

Thanks,
Alex

[Phil Harvey]

Hi Alex,

Ignored superfluous tag name or invalid option: -xmp-vcsPG:graphicType.

You will only get this message if exiftool is in write mode.  One of the arguments in your file must have contained an equal sign or greater/less than symbol.

- Phil

[inanealex]

Ahhh, that makes sense. I did find an errant ">" in the first argfile, but that wasn't the only problem.

It was the >> results.txt that caused the problem.

What I needed was exiftool -T -@ MD_Lookup.txt -@ MD_Files.txt -echo >results.txt