Under Pythonista I can create files via open("file",'w') and read them out with another script later.
Where do these files live and how long do they exists. Killing the app doesn't seem to delete the files.
They exist as long as you don't delete the app. If you don't specify a different folder, files are created in the current directory, which will typically be the one where your script is stored. The built-in file manager only shows .py files, so any other files you create will be invisible in the UI, but you could list them with scripts like Shellista.
Good explanation Thanks omz.