How to compare two strings in dot separated version format in Bash?

Question

Is there any way to compare such strings on bash, e.g.: 2.4.5 and 2.8 and 2.4.5.1?

Answer 1

Here's another pure bash version, rather smaller than the accepted answer. It only checks whether a version is less than or equal to a "minimum version", and it will check alphanumeric sequences lexicographically, which often gives the wrong result ("snapshot" is not later than "release", to give a common example). It will work fine for major/minor.

is_number() {
    case "$BASH_VERSION" in
        3.1.*)
            PATTERN='\^\[0-9\]+\$'
            ;;
        *)
            PATTERN='^[0-9]+$'
            ;;
    esac

    [[ "$1" =~ $PATTERN ]]
}

min_version() {
    if [[ $# != 2 ]]
    then
        echo "Usage: min_version current minimum"
        return
    fi

    A="${1%%.*}"
    B="${2%%.*}"

    if [[ "$A" != "$1" && "$B" != "$2" && "$A" == "$B" ]]
    then
        min_version "${1#*.}" "${2#*.}"
    else
        if is_number "$A" && is_number "$B"
        then
            [[ "$A" -ge "$B" ]]
        else
            [[ ! "$A" < "$B" ]]
        fi
    fi
}