chroot helper

chroot.sh

#!/bin/bash

if [ "$1" != "start" ] && [ "$1" != "stop" ]; then
    echo "usage: ./chroot.sh <start|stop> <rootfs>"
    exit 1;
fi
ACTION=$1

if [ ! -d "$2" ]; then
    echo "error: invalid directory: $2"
    exit 1;
fi
FAKEROOT=$2

set -euo pipefail

MOUNTPOINTS=("/tmp" "/dev/null" "/dev/pts" "/dev/random" "/dev/shm" "/dev/urandom" "/proc")

function stop_chroot() {
    for MOUNTPOINT in "${MOUNTPOINTS[@]}"; do
        echo "unmounting ${FAKEROOT}${MOUNTPOINT}"
        umount "${FAKEROOT}${MOUNTPOINT}" 2> /dev/null || true 
    done
}

function start_chroot() {
    for MOUNTPOINT in "${MOUNTPOINTS[@]}"; do
        echo "mounting ${MOUNTPOINT} > ${FAKEROOT}${MOUNTPOINT}"
        mount -o bind "${MOUNTPOINT}" "${FAKEROOT}${MOUNTPOINT}" 
    done

    chroot "${FAKEROOT}" /bin/bash --login
}

function main() {
    if [ "${ACTION}" == "start" ]; then
        start_chroot
    elif [ "${ACTION}" == "stop" ]; then
        stop_chroot
    fi
}

main