On RedHat/CentOS/rpm systems, there's no dpkg --compare-versions available - sort -V can help to compare version numbers:

version_lt () {
    newest=$( ( echo "$1"; echo "$2" ) | sort -V | tail -n1)
    [ "$1" != "$newest" ]
}

$ version_lt 1.5 1.1 && echo yes
$ version_lt 1.5 1.10 && echo yes
yes