cron_img_previews.sh

#!/bin/bash
folder="preview";
declare -a formats=("png" "jpg" "jpeg" "bmp" "webp");
#mkdir "$folder";
echo "push service: scanning $folder/ ...";
for ext in "${formats[@]}"; do
    for file in *."$ext"; do
        if [ -f "$file" ]; then
            new_file="$folder/${file%.*}.jpg";
            if ! [ -f "./$new_file" ]; then
                echo "converting ./$file -> ./$new_file";
                ffmpeg -i "./$file" -vf scale="300:-1" "./$new_file" -loglevel error;
            fi
        fi
    done
done
echo "push service: scanning complete";