There are many free (non-libre) alternatives to Redshift available on Android. Here's our favorite: CF.lumen.
OBJECTIVE: Set up a customized guest account using Ubuntu MATE that will present the user with specified options, theme, tweaks as well as a folder/file location set by the administration. This guest account will self-destruct and reset normally upon log-out or computer restart.
Sometimes you know what your looking for but more often than not, you need to find some file based off of size and creation/saved/modified date on your Ubuntu server. Here's the command you need to find it and then print the results to a useful [any] file type you need to sort the data.