20 troubleshooting grub persistent password reset rd.break

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GNU GRUB (short for GNU GRand Unified Bootloader) is a boot loader package from the GNU Project.

when finished in rescue/emergency target modes, run
systemctl reboot
this will bring into normal operation mode
=====================
grub2-mkconfig will create a new configuration based on the currently running system, what is found in /boot, what is set in /etc/default/grub

never touch grub.cfg file manually


[root@localhost system]# grub2-mkconfig -o /boot/grub2/grub.cfg 
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-3.10.0-514.el7.x86_64
Found initrd image: /boot/initramfs-3.10.0-514.el7.x86_64.img
Found linux image: /boot/vmlinuz-0-rescue-b249270c260a4b5391e0c516013244aa
Found initrd image: /boot/initramfs-0-rescue-b249270c260a4b5391e0c516013244aa.img
done

below parameters can be modified

[root@localhost system]# cat /etc/default/grub 
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="crashkernel=auto rd.lvm.lv=cl/root rd.lvm.lv=cl/swap rhgb quiet"
GRUB_DISABLE_RECOVERY="true"
[root@localhost system]#
==========================
reset root password

add rd.break to grub after linux16
(in RHEL 6 init=/bin/bash)

ctrl+x to boot

#mount -o remount, rw /sysroot
#chroot /sysroot
#echo newpassword | passwd --stdin root
#touch /.autorelabel
----------
autorelabel file will relabel entire filesystem which will take time
instead of autorelabel we can do the faster option:
1) load SELinux policy using load_policy -i
2) Correct SELinux context type on /etc/shadow: chcon -t shadow_t /etc/shadow
----------
regarding autorelabel:

Next time when you will reboot the system, it will relabel the filesystem for SElinux automatically.
This usually occurs when labeling a file system for SELinux for the first time, or when switching between different types of policy, such as changing from the targeted to the strict policy








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