originaldate.sh

#!/bin/bash
set -e

find .. -type f -iname "*.flac" | while read -r file; do
    date_val=$(metaflac --show-tag=DATE "$file" | sed 's/^DATE=//')
    originaldate_val=$(metaflac --show-tag=ORIGINALDATE "$flac_file" | sed 's/^ORIGINALDATE=//')

    if [[ -n "$date_val" && -n "$originaldate_val" && "$date_val" != "$originaldate_val" ]]; then
        echo "$file"
        echo "  $date_val -> $originaldate_val"

        metaflac --remove-tag=DATE "$file"
        metaflac --set-tag="DATE=$originaldate_val" "$file"
    fi
done