diff --git a/chr.sh b/chr.sh
index e57c9ff..647e4a9 100644
--- a/chr.sh
+++ b/chr.sh
@@ -1,25 +1,47 @@
-curl -# -L  https://github.com/elseif/MikroTikPatch/releases/download/7.19.4/chr-7.19.4-legacy-bios.img.zip -o /tmp/chr.img.zip  && cd /tmp && \
-unzip -p chr.img.zip > chr.img && \
-STORAGE=`lsblk | grep disk | cut -d ' ' -f 1 | head -n 1` && \
-echo STORAGE is $STORAGE && \
-ETH=`ip route show default | sed -n 's/.* dev \([^\ ]*\) .*/\1/p'` && \
-echo ETH is $ETH && \
-ADDRESS=`ip addr show $ETH | grep global | cut -d' ' -f 6 | head -n 1` && \
-echo ADDRESS is $ADDRESS && \
-GATEWAY=`ip route list | grep default | cut -d' ' -f 3` && \
-echo GATEWAY is $GATEWAY && \
-LOOP=`losetup -Pf --show chr.img` && \
-sleep 3 && \
-MNT=/mnt/chr && \
-mkdir -p $MNT && \
-mount ${LOOP}p2 $MNT && \
+#!/bin/sh
+set -e
+curl -# -L https://github.com/elseif/MikroTikPatch/releases/download/7.19.4/chr-7.19.4-legacy-bios.img.zip -o /tmp/chr.img.zip
+cd /tmp
+unzip -p chr.img.zip > chr.img
+
+STORAGE=$(for d in /sys/block/*; do
+    case $(basename $d) in
+        loop*|ram*|sr*) continue ;;
+        *) echo $(basename $d); break ;;
+    esac
+done)
+echo "STORAGE is $STORAGE"
+
+ETH=$(ip route show default | sed -n 's/.* dev \([^\ ]*\) .*/\1/p')
+echo "ETH is $ETH"
+
+ADDRESS=$(ip addr show $ETH | grep global | cut -d' ' -f 6 | head -n 1)
+echo "ADDRESS is $ADDRESS"
+
+GATEWAY=$(ip route list | grep default | cut -d' ' -f 3)
+echo "GATEWAY is $GATEWAY"
+
+LOOP=$(losetup -Pf --show chr.img)
+echo "LOOP device is $LOOP"
+sleep 3
+
+MNT=/mnt/chr
+mkdir -p $MNT
+mount ${LOOP}p2 $MNT
+
 cat <<EOF | tee $MNT/rw/autorun.scr
 /ip address add address=$ADDRESS interface=ether1
 /ip route add gateway=$GATEWAY
 EOF
-umount $MNT && \
-losetup -d $LOOP && \
-dd if=chr.img of=/dev/$STORAGE bs=4M oflag=sync status=progress && \
-echo "Ok, reboot" && \
-echo 1 > /proc/sys/kernel/sysrq && \
+
+umount $MNT
+losetup -d $LOOP
+
+echo "WARNING: All data on /dev/$STORAGE will be lost!"
+read -p "Do you want to continue? [Y/n]: " confirm
+[ "$confirm" = "n" ] && echo "Operation aborted." && exit 1
+
+dd if=chr.img of=/dev/$STORAGE bs=4M oflag=sync status=progress
+echo "Ok, rebooting..."
+echo 1 > /proc/sys/kernel/sysrq
 echo b > /proc/sysrq-trigger