When installing Debian on a new system, if you don’t install Plymouth and you use full disk encryption, the passphrase prompt will come up in a text console which is not very pleasing to the modern eye:
After much experimentation, I found the Joy theme from the available Plymouth themes provided a much better experience. It was created by Audrien Auburg and adapted from an Edubuntu theme by Jonathan Carter for use with Plymouth. This is an excellent example of Ubuntu functionality brought back into Debian for the benefit of all.
This is how to install such a boot theme in a new Debian system using an Intel graphics chipset:
$ sudo -s
# apt-get install plymouth plymouth-drm
Edit /etc/initramfs-tools/modules and add the modules required for modesetting:
Apply the Joy theme and make the changes effective:
# /usr/sbin/plymouth-set-default-theme joy
# update-initramfs -u
And here is the result:
If you have another graphics chipset, or if you want more details about setting Plymouth or changing to other themes, check the Debian wiki documentation about Plymouth for more specific instructions.
Also keep in mind this is not very useful on fast SSD-equiped systems: if you don’t use full-disk encryption, the boot sequence is so fast that you won’t see the theme much!1