Automatic installation of MikroTik Router OS (MikroTik CHR)

#!/bin/bash
set -euo pipefail

# Include sbin paths
export PATH="$PATH:/usr/bin:/bin:/usr/sbin:/sbin"

# Auto-detect target disk (vda vs sda)
if [ -b /dev/vda ]; then
  export TARGET_DISK=/dev/vda
elif [ -b /dev/sda ]; then
  export TARGET_DISK=/dev/sda
else
  echo "ERROR: Neither /dev/vda nor /dev/sda found. Available disks:" >&2
  lsblk -d -o NAME,SIZE,TYPE >&2
  exit 1
fi
echo "Using TARGET_DISK=$TARGET_DISK"

sudo apt-get update && sudo apt-get upgrade -y
# add parted for partprobe; util-linux provides fdisk
sudo apt-get -y install gzip unzip curl wget util-linux ca-certificates parted

# Latest stable RouterOS v7
latest_version="$(curl -fsSL https://download.mikrotik.com/routeros/NEWESTa7.stable | awk '{print $1}')"

# CHR RAW disk image
ZIP="chr-${latest_version}.img.zip"
IMG="chr-${latest_version}.img"
download_url="https://download.mikrotik.com/routeros/${latest_version}/${ZIP}"

# Download + extract
wget -O "$ZIP" "$download_url"
rm -f "$IMG"
unzip -o "$ZIP" "$IMG"

# Attach image with partition scan
LOOP="$(sudo losetup --find --show --partscan "$IMG")"
sudo udevadm settle 2>/dev/null || true
lsblk "$LOOP"

cleanup() {
  set +e
  sudo umount /mnt/image 2>/dev/null || true
  sudo losetup -d "$LOOP" 2>/dev/null || true
}
trap cleanup EXIT

# Mount partition for injection:
# Prefer p2 first (typically main filesystem) then p1
sudo mkdir -p /mnt/image
MOUNTED=0
for p in "${LOOP}p2" "${LOOP}p1"; do
  [ -b "$p" ] || continue
  if sudo mount "$p" /mnt/image 2>/dev/null; then
    if sudo sh -c 'touch /mnt/image/.writetest && rm -f /mnt/image/.writetest'; then
      MOUNTED=1
      echo "Mounted writable partition: $p"
      break
    fi
    sudo umount /mnt/image
  fi
done

if [ "$MOUNTED" != "1" ]; then
  echo "ERROR: Could not mount a writable partition inside CHR image ($IMG)." >&2
  exit 1
fi

sync
sudo umount /mnt/image
sudo losetup -d "$LOOP"
trap - EXIT

# Write CHR image to disk
echo u | sudo tee /proc/sysrq-trigger >/dev/null
sudo dd if="$IMG" bs=4M of="$TARGET_DISK" status=progress conv=fsync
sudo sync

# Verify layout best-effort
sudo partprobe "$TARGET_DISK" 2>/dev/null || true
lsblk "$TARGET_DISK" || true
sudo fdisk -l "$TARGET_DISK" 2>/dev/null || true

echo s | sudo tee /proc/sysrq-trigger >/dev/null

echo "Waiting 5 seconds..."
end_time=$((SECONDS + 5))
while [ $SECONDS -lt $end_time ]; do :; done

echo "Reboot OS"
echo b | sudo tee /proc/sysrq-trigger >/dev/null