An alias to verify that installed files are unchanged using dpkg package's md5sums

dpkg-verify.alias.sh

dpkg-verify() {
    exitcode=0
    for file in $*; do
        pkg=`dpkg -S "$file" | cut -d: -f 1`
        hashfile="/var/lib/dpkg/info/$pkg.md5sums"
        if [ -s "$hashfile" ]; then
            rfile=`echo "$file" | cut -d/ -f 2-`
            phash=`grep -E "$rfile\$" "$hashfile" | cut -d\  -f 1`
            hash=`md5sum "$file" | cut -d\  -f 1`
            if [ "$hash" = "$phash" ]; then
                echo "$file: ok"
            else
                echo "$file: CHANGED"
                exitcode=1
            fi
        else
            echo "$file: UNKNOWN"
            exitcode=1
        fi
    done
    return $exitcode
}

Try it with installed isc-dhcp-server package, and use the /sbin/dhclient then you'll find that dpkg picks up isc-dhcp-server-ddns instead. Which is not supposed to happened, but it does... anyway.