Silent boot Debian 10

silent_boot.sh

#!/bin/bash
if [[ $EUID -ne 0 ]]; then
   echo "This script must be run as root" 
   exit 1
fi
echo 'GRUB_DEFAULT=0' > /etc/default/grub
echo 'GRUB_TIMEOUT=5' >> /etc/default/grub
echo 'GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`' >> /etc/default/grub
echo 'GRUB_CMDLINE_LINUX_DEFAULT="quiet loglevel=3 vga=current rd.systemd.show_status=auto rd.udev.log-priority=3 vt.global_cursor_default=0"' >> /etc/default/grub
echo 'GRUB_CMDLINE_LINUX="console=ttyS0"' >> /etc/default/grub

update-grub

sed -e '/echo/ s/^#*/#/g' -i file /boot/grub/grub.cfg

sed -e 's/cyan/white/g' -i /boot/grub/grub.cfg
sed -e 's/blue/black/g' -i /boot/grub/grub.cfg


systemctl disable getty@tty1.service # Hide tty login prompt at tty1