debian installer for non-debian OS

#!/bin/sh
if [ $USER != "root" ]
    then
        echo "Sorry, we need root"
        exit
    fi
if [ ! -f $1 ]
    then
        echo "Provided file doesnt exist"
        exit
    fi
cp $1 /tmp
cd /tmp
ar x $1
if [ ! -f "data.tar.gz" ]
    then
        echo "Invalid debian installer"
        exit
    fi
mv data.tar.gz /
cd /
tar xzfv data.tar.gz

rm data.tar.gz /tmp/control.tar.gz /tmp/debian-binary

echo "All done (most likely)"