Notes from repairing a Fedora drive.
Mount system in chroot.
If the system is a raid drive and your not able to access it refer to this post. May just need to install the raid utilities.
For mounting the chroot environment refer to this post
Repairing grub
yum install grub2-efi-*
Install grub. Change /sda to your drive, may need to specify the efi partition.
grub2-install /dev/sda
If your boot and efi partitions are mounted.
grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
Reboot.
The reason is probably because the chrooted environment can’t resolve DNS.
Test it with
ping incredigeek.com
If it is not resolving, edit “/etc/resolv.conf” and change/add your nameserver. Or just replace everything in it with
echo "nameserver 4.2.2.2" > /etc/resolv.conf
It should now be able to resolve and you should be able to use yum, or dnf.
yum update
Chrooting can be super useful for changing things like the root password, repairing grub bootloader etc., things that require the system to be mounted. Typically if your chrooting into an OS drive you can boot up on a Live Linux distro, or use the Rescue feature on some Linux installers.
Mount main drive
Change sdb2 to the root partition of your drive.
mount /dev/sdb2 /mnt
Mount other stuff
mount -t proc none /mnt/proc mount -o bind /dev /mnt/dev mount -o bind /sys /mnt/sys mount -o bind /run /mnt/run
If you want to, you can mount the boot partition. Change sdb1 if your boot partition is something else. For efi, you may need to mount the boot partition then mount the efi partition inside /boot/efi.
mount /dev/sdb1 /mnt/boot
Chroot
chroot /mnt
You should now be inside the chroot environment. To exit the chroot, hit control+d or type exit.
If your having issues resolving DNS refer to this post.