Quotation marks in subject interacting poorly with -args argument

[alanterra]

Hi

I have been trying to track down a bug in a script I am writing, and I think I isolated it. I'm not sure if this is a bug or a feature in exiftool.

If you put a quote in a subject tag
exiftool -subject+='A "quoted" subject' -subject+='An unquoted subject' test.JPG
and then you try to transfer the tags to another image via writing and reading to a text file
exiftool -args -subject test.JPG > temp.txt
exiftool -@ temp.txt test2.JPG
the tags do not come over as you would wish. Looking at the tags in Photoshop (which uses a semicolon as a separator), the tags of the first file are

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A "quoted" subject; An unquoted subject

but the tags of the second file are

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"A ""quoted"" subject, An unquoted subject"

or, in other words, the first file has two tags, but the second has one tag.

What I am trying to do is to pull the tags from a file, run them through a script, and then reapply them to the file. Of course, the best thing would be to get rid of the quotes in the tags, which I will probably do. But I thought that this bug report (if it is a bug) might be useful.

[Phil Harvey]

When outputting a list-type tag using the -args option, the individual items are concatenated (by default with a ", " separator).  So when reading this back, you should use -sep ", ".

Also, if you want to preserve XMP structures, you may want to add -struct to the exporting command.

- Phil

[alanterra]

Huh.

I had been using -s3 -subject to write out the subject tags, modify them, and read them back in, and using the -sep ", " didn't help. I've lost the details of that version of my script, but I was seeing the final carriage return in the text file find its way into the last tag entered. (Carriage return is signified by a "." character when you display your tags, and it took me a long time to figure out what that meant!)

But you are right (of course), using -args for output and -sep ', " on input solves this problem perfectly. Now I don't have to remove the quote that snuck into my subject tags a long time ago (long before I even knew what metadata were). I suspect that for my purposes I don't want to use the -struct tag, but I am trying to figure that out.

Thanks once again!

[Phil Harvey]

You're right that you could wind up with a newline be importing the output from -s3, but the -sep option should still work:

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> exiftool a.jpg -subject=1 -subject=2 -subject=3
    1 image files updated
> exiftool a.jpg -subject -s3 > t1
> ./hexdump t1
    0000: 31 2c 20 32 2c 20 33 0a                         [1, 2, 3.]
> ./exiftool a.jpg "-subject<=t1" -sep ", "
    1 image files updated
> exiftool a.jpg -subject -sep ";"
Subject                         : 1;2;3.

- Phil