delete all xmp keywords except for those specified

[Yalkov]

I want to delete all xmp:subject keywords except those specified. I was unable to figure it out from the examples here https://exiftool.org/exiftool_pod.html#WRITING-EXAMPLES

Can someone please provide an example command to do this?

If it matters, I will be using this command in an argument file.

[StarGeek]

Please do not make duplicate posts.

Your question was answered here.  Clear the subject then add your specified keywords back in without using -=/+=.

[Yalkov]

Hi,

I did not think it was a duplicate post, sorry, maybe I didn't get it across well or I do not understand.  I want to KEEP an existing set of keywords, but remove ALL OTHERS. I do not know what keywords are in the file already.

The problem is that a file may have one of 50 important keywords to keep, but I do not know without reading them ahead of time which of the 50 are actually in the file. I hope this makes sense...
I also have no idea what other keywords might exist in the same file. I do not want to add all 50 of the important keywords, just the keywords that the file already had (which I do not know ahead of time), and delete everything else.

The other post was about adding new keywords regardless of whatever keywords existed by first deleting all existing keywords. So I did not care about preservation of existing keywords in that case.

If it still is a duplicate I do not understand but would still appreciate help! 

[StarGeek]

Ok, that's a much more complex operation and the command will be quite long with a list of 50 keywords.

You would want to use a command similar to this post except you would use $_=undef if not /pipe|separated|list/}

exiftool "-Subject<${Subject@;$_=undef if not /^(pipe|separated|list)$/}" -sep "--" /path/to/files/

You would put your list of keywords, separated by the pipe character | between the parentheses.  This is a RegEx (Regular Expression) match if you are familiar with them.

Example output.  Notice that "Pipe" was removed as this is a case sensitive operation.  To make it case insensitive, you would add an i after $/.  The addition of ^( and )$ was to make sure that substrings were not matched, as in the example case of "pipe dream".  Remove them if you want to match substrings.

Code Select Expand

C:\>exiftool -g1 -a -s -Subject y:\!temp\Test4.jpg
---- XMP-dc ----
Subject                         : Pipe, pipe, pipe dream, separated

C:\>exiftool -P -overwrite_original "-Subject<${Subject@;$_=undef if not /^(pipe|separated|list)$/}" -sep "--" y:\!temp\Test4.jpg
    1 image files updated

C:\>exiftool -g1 -a -s -Subject y:\!temp\Test4.jpg
---- XMP-dc ----
Subject                         : pipe, separated