Added Readme and fixed no magick installation

modules/wp/generate-wallpaper-thumbs.sh

@@ -26,6 +26,11 @@ for img in "$WALLPAPER_DIR"/*.{jpg,jpeg,png}; do
 
     # Get just the filename
     fname=$(basename "$img")
+    name="${fname%.*}"
+    ext="${fname##*.}"
+
+    # no magick file:
+    temp_image_name="$THUMB_DIR/${name}_tmp.${ext}" 
 
     # Output path
     thumb="$THUMB_DIR/$fname"
@@ -38,7 +43,15 @@ for img in "$WALLPAPER_DIR"/*.{jpg,jpeg,png}; do
     num+=1
 
     # Generate thumbnail using ImageMagick
-    magick "$img" -resize "${MAX_DIM}x${MAX_DIM}" "$thumb"
+    if [ -x "/usr/bin/magick" ] then
+        magick "$img" -resize "${MAX_DIM}x${MAX_DIM}" "$thumb"
+        rm $temp_image_name
+    else
+        if [ -f "$temp_image_name" ] && [ "$temp_image_name" -nt "$img" ]; then
+            continue
+        fi
+        cp $img $temp_image_name
+    fi
 done
 
 echo "$num Thumbnails generated in $THUMB_DIR"