Chroot into a device or file taking care of mounting proc, sysfs, /dev, setting mount options, umounting, etc

Inception

#!/bin/bash

function ifloop {
        # If it is NOT a file in /dev, assume file loopback mount
        if [[ ! $1 =~ /dev/* ]]
        then   
                echo "-o loop"
        fi
}

function usage {
        echo "./inception <file/device> <mountpoint>"
        echo "For undoing, use ./inception -d <mountpoint> "
}

function inception {
        DEVICE=$1
        MOUNTPOINT=$2
        MOUNTOPT=$3

        mount $MOUNTOPT $DEVICE $MOUNTPOINT
        mount -t proc proc ${MOUNTPOINT}/proc
        mount -t sysfs sys ${MOUNTPOINT}/sys
        mount -o bind /dev ${MOUNTPOINT}/dev
        chroot $MOUNTPOINT /bin/bash
}

function wake {
        MOUNTPOINT=$1

        umount ${MOUNTPOINT}/dev
        umount ${MOUNTPOINT}/sys
        umount ${MOUNTPOINT}/proc
        umount $MOUNTPOINT
}

if [ "$1" == "-d" ]
then   
        echo "Inception level down..."
        MOUNTPOINT=$2

        if [ $# -ne 2 ]
        then   
                usage
                exit
        fi

        wake "$MOUNTPOINT"

        exit
fi

DEVICE=$1
MOUNTPOINT=$2
MOUNTOPT=$(ifloop "$DEVICE")

if [ $# -ne 2 ]
then
        usage
        exit
fi

echo "Inception level up..."

inception "$DEVICE" "$MOUNTPOINT" "$MOUNTOPT"