chroot wrapper that mounts important filesystems and copies resolv.conf beforehands to make internet, sudo, and more work correctly inside the chroot

chrootwrapper.sh

#!/bin/bash
[[ !  "$(id -u)" = "0" ]] && echo "This script must be ran as root!" && exit 1

CHROOTDIR="$(readlink -f $1)"; shift

# Functions
mount_dirs() {
   ! mount | grep "$CHROOTDIR$1" &>/dev/null && mount --bind "$1" "$CHROOTDIR$1"
}

umount_dirs() {
  umount "$CHROOTDIR$1"
}

# Main
cp /etc/resolv.conf "$CHROOTDIR"/etc/resolv.conf
dirs=("/proc" "/sys" "/dev" "/dev/shm" "/dev/pts")
for dir in ${dirs[@]}; do
	mount_dirs "$dir"
done

chroot "$CHROOTDIR" $@

udirs=("/proc" "/sys" "/dev/shm" "/dev/pts" "/dev")
for udir in ${udirs[@]}; do
	umount_dirs "$udir"
done