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 a refinement of the top answer (Dennis's) that is more concise and uses a different return value scheme to make it easy to implement <= and >= with a single comparison. It also compares everything after the first character not in [0-9.] lexicographically, so 1.0rc1 < 1.0rc2.

# Compares two tuple-based, dot-delimited version numbers a and b (possibly
# with arbitrary string suffixes). Returns:
# 1 if ab
# Everything after the first character not in [0-9.] is compared
# lexicographically using ASCII ordering if the tuple-based versions are equal.
compare-versions() {
    if [[ $1 == $2 ]]; then
        return 2
    fi
    local IFS=.
    local i a=(${1%%[^0-9.]*}) b=(${2%%[^0-9.]*})
    local arem=${1#${1%%[^0-9.]*}} brem=${2#${2%%[^0-9.]*}}
    for ((i=0; i<${#a[@]} || i<${#b[@]}; i++)); do
        if ((10#${a[i]:-0} < 10#${b[i]:-0})); then
            return 1
        elif ((10#${a[i]:-0} > 10#${b[i]:-0})); then
            return 3
        fi
    done
    if [ "$arem" '<' "$brem" ]; then
        return 1
    elif [ "$arem" '>' "$brem" ]; then
        return 3
    fi
    return 2
}