Copie este script como mount-root
no seu dispositivo usb
#!/bin/bash
if [ "$(whoami &2>/dev/null)" != "root" ] && [ "$(id -un &2>/dev/null)" != "root" ] ; then
echo "You must be root to run this script!"; echo "use 'sudo !!'"; exit 1
fi
if [ $# -ne 2 ]; then
echo "calling this script with only two options with the device and mountpoint"
echo "for example"
echo "mount-root /dev/sda1 /media/other/"
set -x
fdisk -l
lsblk -f
exit
fi
D=$(echo $1 | sed 's:/$::')
M=$(echo $2 | sed 's:/$::')
echo mounting $D to $M
mkdir -p $M
mount $D $M
mount -t proc none $M/proc
mount -o bind /dev $M/dev
mount -t sysfs sys $M/sys
mount --bind /dev/pts $M/dev/pts
cp /proc/mounts $M/etc/mtab
chroot $M/ /bin/bash
fonte: link