Edit boot menu on-the-go
0. reboot the CentOS 7 and press ESC when GRUB menu show up on the screen and press “e”
1. find “ro” on “linux16” section and then change to “rw init=/sysroot/bin/sh”
2. press “CTRL + x” to reboot CentOS to init sh mode and start to reset root password
chroot sysroot
after booting on init sh mode, run this command:
chroot /sysroot
reset root password
passwd root
reinitial selinux
touch /.autorelabel
exit from chroot
exit
reboot CentOS 7
reboot
