If the image-file doesn't have one (or more) of the tags, what does the field on the ouput file contain?
DateTaken
FileModifyDate
FileAccessDate
FileCreateDate
ModifyDate
CreateDate
Assuming you're referring to your previous post about csv files.
If none of the files have the tag, then no column containing that tag is created. If some of the files have the tag, but not others, then there is a column for that tag but the cell is left empty for files that don't have that tag.
One thing that needs to be pointed out is that there is no such thing as a DateTaken tag. That is a Windows Property and it is filled from a variety of tags, depending upon what is available. See this post (https://exiftool.org/forum/index.php/topic,6591.msg32875.html#msg32875) for what tags Windows uses to fill various properties.
Why isn't -f causing a dash (-) to be written to the output record if the tag has no data?
What is your exact command?
My test here shows that it works.
C:\>exiftool -f -csv -MadeUpTagName y:\X_Drive\!temp\Test3.jpg
SourceFile,MadeUpTagName
y:/X_Drive/!temp/Test3.jpg,-
exiftool -csv -filepath -T -f -r -ext jpg -ext jpeg -ext png -datetimeoriginal -DateTaken -FileModifyDate -FileAccessDate -FileCreateDate -ModifyDate -CreateDate -model -filesize -imagesize -megapixels . > newjpg.txt
Can you show a few lines of the CSV where this happens? The output here is correct, with non-existent tags (such as DateTaken) filled with hyphens.
Please re-read the third paragraph of my first post in the is thread. DateTake isn't a tag, it's a property of Windows and is filled from a variety of tags.
What version of exiftool are you using? Type exiftool -ver to find out.