/lib/plymouth/themes/solar/solar.plymouth is in plymouth-theme-solar 0.8.2-2ubuntu30.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | [Plymouth Theme]
Name=Solar
Description=Space theme with violent flaring blue star
ModuleName=space-flares
[space-flares]
ImageDir=/lib/plymouth/themes/solar
|