What exactly is this doing?
When you boot up in graphical mode, Plymouth is responsible for presenting "filling Fedora bubble" gui screen during the boot process. You can see the "text" version of this while this is happening simply by pressing the ESC key during that segment of the bootup process.
The "filling Fedora bubble" is Plymouth's "charge" theme. With the command I gave, you are fisrt, changing to root user using the "su" command, then changing the plymouth theme from "charge" to "details". The details themes is a non-gui console theme (actually no theme at all, just the console display) that shows you all the text output to the console that would also appear in your boot.log file.
The "--rebuild-initrd" part of this command causes a rebuild of the /boot/initrd-plymouth.img file. I use the "details" theme on my desktop pc. I prefer seeing the boot up messages rather than a somewhat boring bubble/balloon/logo filling up that is acting as nothing more than a progress bar.
BASH:~/-> plymouth-set-default-theme --list
There are other plymouth themes in the repos.... "yum list plymouth-theme*"
---------- Post added at 03:31 PM ---------- Previous post was at 03:23 PM ----------
Note: You do not need to remove either the "quiet" or "rhgb" entries in your grub boot line for this to work.