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@nilox94
Created April 7, 2020 01:55
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chroot from live cd
#! /bin/bash
# select target root partition
if [ $1 ]
then
root=$1
else
# asuming the system is at the first ext partition
root=/dev/`lsblk -f | awk '
$2 ~ "ext" {
print substr($1, 3);
exit;
}
'`
fi
if [ $2 ]
then
efi=$2
else
# select first vfat partition that is not inside an iso image (that should be the EFI)
iso=`lsblk -f | awk '
$1 ~ "^s" && $2 ~ "iso" {
print $1
}
'`
efi=/dev/`lsblk -f | awk -v iso=$iso '
BEGIN {
gsub("\n", "|", iso);
}
$1 !~ iso && $2 == "vfat" {
print substr($1, 3); # remove |- prefix
exit;
}
'`
fi
echo "selected '$root' as target root partition"
echo "selected '$efi' as target EFI partition"
read -p "Do you want to continue? [y/N] " -n 1 -r
echo
if [[ ! $REPLY =~ ^[Yy]$ ]]
then
echo 'usage:'
echo ' sudo ./livecd2chroot.sh [/root/partition/device/path [/efi/partition/device/path]]'
exit 1
fi
# prepare new root fs as it is stated in the superuser community wiki
# https://superuser.com/questions/111152/whats-the-proper-way-to-prepare-chroot-to-recover-a-broken-linux-installation
# mount fs
umount $root 2>/dev/null
umount $root 2>/dev/null
mount $root /mnt
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
mount --bind /dev /mnt/dev
mount --bind /run /mnt/run
mount $efi /mnt/boot/efi
# copy network config
cp -L /etc/resolv.conf /mnt/etc/resolv.conf
# setup .bashrc
# add fancy prompt
echo 'export PS1="(chroot) $PS1"' >> /mnt/root/.bashrc
# update mtab (to operate grub)
echo 'grep -v rootfs /proc/mounts 2>/dev/null > /etc/mtab' >> /mnt/root/.bashrc
# ch[ange-]root!!
chroot /mnt /bin/bash
# restore .bashrc
sed -i '$d' /mnt/root/.bashrc
sed -i '$d' /mnt/root/.bashrc
# unmount fs
umount /mnt/boot/efi
umount /mnt/{proc,sys,dev,run}
umount /mnt
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