Circular - Update Extension and Meta Data

[grimacing-visor]

I'm trying to deal with some Apple screenshots that are being saved as PNG but the metadata is image/jpeg.

exiftool steps in to save the day with clearing up the extension mess with:

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exiftool "-filename<%f.$fileTypeExtension" -ext PNG IMG_REALLY_JPG.PNG
but there is no date meta data in the image and the rewrite loses the only date that makes any sense which is FileModifyDate.  I tried to get fancy with the following but I think it's too circular:

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exiftool "-filename<%f.$fileTypeExtension" "-DateTimeOriginal<FileModifyDate" -if 'not $datetimeoriginal' -ext PNG IMG_REALLY_JPG.PNG

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Error: Not a valid PNG (looks more like a JPEG) - IMG_PNG_TEST.PNG
    0 image files updated
    1 files weren't updated due to errors
Any tips on correcting the PNG files to jpeg (if applicable) and add the original FileModifyDate if one is missing?

[Phil Harvey]

Just renaming the file doesn't change the FileModifyDate on Mac or Linux.  I really hate it when someone makes me fire up my Windows virtual machine, but I tested this and it is true for Windows too.

The FileModifyDate will only change if you actually make a change to the data in the file without using the -P option.

- Phil

[grimacing-visor]

Thanks for the quick reply Phil.  No need for the VM this is on a Mac.  Let me triple check the dates on my end.  I gather that the command should work then.

Update: You're correct, FileModifyDate didn't change, the other dates did.  False alarm.

[Phil Harvey]

If you are on Mac, you should be using single quotes around arguments containing a "$".

- Phil