Grand Unified Boot Loader
/etc/default/grub – the most important.
# cd /etc/default/
# vi grub
Here are the parameters.
rhgb quite is a parameter which not allow grub to show what is doing while is booting.
Rest of configuration is in:
# /etc/grub.d
After changing the configuration, must load them:
# grub2-mkconfig
# reboot
go to menu and go to kernel line and press ctrl+x to exit and continue the boot procedure.