System recovery technology of [basic part]
System recovery technology
Recovery method of 1.mbr error
Dd if=/dev/zero of=/dev/vda bs=446 count=1
Reboot
Open the virtual manager at this time
Boot with CD or network card
Select troubleshooting
Select rescue a red hat.
The original root directory will be mounted to / mnt/sysimage
Choose to continue
Enter grub2-install / dev/vda
Then ctrl+d twice.
Force shutdown to change the first boot item to hard disk boot
two。 Delete grub2.cfg
Enter / boot/grub2/
Delete grub2.cfg
Reboot
Enter grub2-mkconfig > / boot/grub2/grub.cfg after successfully opening it.
If there is no ip input / etc/init.d/network restart
Yum install
3. Delete img
Enter / boot to delete initXXXXXXXXXXX.img
Delete vmliXXXXXXXXXXXXX.img
CD-ROM starts rescue mode
Yum install lftp-y
Lftp IP installs Paclages kernel-3.10 in yum source
Exit restart and change the hard disk to the first startup item
4. Modify the password
Forget the root password:
First change selinux to disabled
Press e to edit when booting
Delete the position from 8 to ro
Change it to rw rd.break
Ctrl+x
5. Modify link
Rm-fr / etc/systemd/system/default.target
Ln-s / usr/lib/systemd/system/poweroff.target / etc/systemd/system/default.target
System paralysis
Select kernel and press e to edit
Force to interrupt the system on
Rm-fr / etc/systemd/system/default.target
Ln-s / usr/lib/systemd/system/graphical.target
/ etc/systemd/system/default.target
Graphical.target is to launch the physical graphical interface.
