There is no longer any theme data in the database with PrestaShop 1.7. Hence a theme is installed as soon as it is on the disk.
If you want the theme to appears in the backoffice, it only needs to contain a
This will only display it, if you want to select it as your active theme, it has to be valid. Read “What
makes a valid theme”.
Once it is active you can export your theme using the “Export current theme” button or use the command from your terminal.
php bin/console prestashop:theme:export THEME_DIRECTORY_NAME
php app/consoleinstead of
php bin/consolefor versions prior to 1.7.4
Exporting your theme using the button or the command line will export the following data:
theme.yml(See theme.yml doc)