Generate JPEG thumbnails recursively, robust against whitespace in paths

generate_thumbs.sh

#!/bin/bash
# Generate JPEG thumbnails recursively, robust against whitespace in paths

if [ "$1" == "--help" ] || [ "$1" == "-h" ]
then
    echo "Usage: ./generate_thumbnails.sh SOURCE_DIR TARGET_DIR"
    echo "Generate thumbnails from JPEG images in a given source folder, to a given target folder."
    echo "Subfolders are visited recursively, and maintained in the target dir. Spaces in file names are allowed."
    echo
    exit
fi

if [ -z $1 ] || [ -z $2 ]; then echo "usage: generate_thumbs.sh source_dir/ target_dir/"; exit 1; fi

CONVERT_GEOMETRY="670"
FULLS_PATH=$1
THUMBS_PATH=$2
THUMBS_PATH_ABSOLUTE=`realpath "$THUMBS_PATH"` &&
FULLS_PATH_ABSOLUTE=`realpath "$FULLS_PATH"` &&
CWD=`pwd` &&

if [ ! -d "$FULLS_PATH_ABSOLUTE" ]; then echo "Folder $FULLS_PATH_ABSOLUTE does not exist."; exit 1; fi

echo "Generating tumbnails for $FULLS_PATH_ABSOLUTE in folder $THUMBS_PATH_ABSOLUTE"
mkdir -p "$THUMBS_PATH"
cd $FULLS_PATH &&
shopt -s globstar &&
for source_path in ./**/*.jpg ./**/*.jpeg
do
    source_relative_path=`realpath --relative-to=. "$source_path"` &&
    target_path="$THUMBS_PATH_ABSOLUTE/$source_relative_path" &&
    target_dir=`dirname "$target_path"` &&

    mkdir -p "$target_dir"
    convert -quality 50 -thumbnail "x$CONVERT_GEOMETRY" "$source_path" "$target_path"

    echo "Tumbnail generated for $source_relative_path"
done