How to write a script that does collectstatic for django

You can try

python manage.py collectstatic --noinput

Why not just send yes to the input of manage.py:

python manage.py collectstatic --settings=app.settings_mark <<<yes &&
./testscript.sh

Or:

echo yes | python manage.py collectstatic --settings=app.settings_mark &&
./testscript.sh