Is there an "update only" mode (do not create new tags)?

[busywait]

Hello,

I'd like to find a command that updates existing tag values only - that is, I want values to be written only if the tag already exists.

For example
exiftool -FNumber=5.6 -FocalLength=200mm file.xmp

I only want the either FNumber or FocalLength to be written if these attributes were already in the .xmp file.

Is this possible?

Thanks in advance for any help you can give,
Steven

[StarGeek]

I think -wm w is what you want. 

[busywait]

It looks perfect, thank you

Unfortunately it's not working for me right away - "Ignored superfluous tag name or invalid option"

I have
-wm w
inside an argument file called _interactiveOptions.txt
and I see error
Ignored superfluous tag name or invalid option: -wm w


exiftool.exe -execute -if "-e $filepath" -srcfile "%d%f.xmp" -@ "_sidecarFormats.txt" -common_args -@ "_interactiveOptions.txt" -@ "Lens.txt" "img.ORF"

Ignored superfluous tag name or invalid option: -wm w
======== C:/pics/img.ORF [1/1]
    1 image files updated
Ignored superfluous tag name or invalid option: -wm w
======== C:/pics.xmp [1/1]
    1 image files updated


This is with exiftool 10.36 on Windows 10.

I'll try and simplify my command...

[busywait]

Although -wm w is ignored in my command file, it worked right away as I wanted it to in the command line.

Thanks for your help!
Steven

[StarGeek]

In the arg file it should be two lines

Code Select Expand

-wm
w

One argument per line, not one option per line.