#!/bin/sh
 
# put a version number "1.2.3.4" in the form "1 2 3 4"
filter_version()
{
    echo $1 | sed 's/\./ /g'
}
 
# reverse the order: "1 2 3 4" become "4 3 2 1"
reverse_order()
{
    for n in $@
    do
        reverse="$n $reverse";
    done
 
    echo $reverse
}
 
# build an integer version number 
build_version()
{
    multiplier=1
    version=0;
 
    for i in $@
    do
        temp=$(( $multiplier * $i ))
        version=$(( $version + $temp ))
        multiplier=$(( $multiplier * 1000 ))
    done
 
    echo $version
}
 
# example
VERSION="1.2.3.4"
filtered=$(filter_version $VERSION)
reversed=$(reverse_order $filtered)
 
build_version $reversed