Add an exif tag to a picture using exiftool

Question

I need to add a tag named "Image Description" to a picture. However, nothing is changed. What am I missing?

cd /tmp/

wget https://i.imgur.com/jGwDTpL.jpg
pic=jGwDTpL.jpg

exiftool -Exif:ImageDescription-="foo" $pic
exiftool -Description-="foo" $pic
exiftool $pic | grep "Image Description"

Answer 1

The -= operation is remove. To add a tag, just assign it:

exiftool -Exif:ImageDescription="foo" -Description="foo" "$pic"
exiftool "$pic" | grep "Image Description"

Remember to double-quote your variables ("$pic" in this example) to protect them from shell expansion and globbing

exiftool documentation is available as part of the tool itself, or online