DRAFT: Avoid using the potentially non standard compliant lsb_release command

[Matombo]

Alternative to #257

Check the distribution the way dkms.in does it and not solely rely und the lsb_release command.

Not yet tested.

[evelikov]

(Copy/paste for cross-referencing purposes)

I've proposed removing the common.postinst script with #339. If you think that may cause issue please reply in there.

If we end up removing it, this MR will no longer be needed.

[bac0n]

I have redone my distro_version function (original only check from the beginning of the running_distibution= string):

distro_version(){
    local ID ID_LIKE
    for f in /etc/os-release /usr/lib/os-release; do
        [[ -r $f ]] && ( . "$f" && echo "${ID_LIKE:-$ID}" ) && return
    done
    die 4 "System is missing os-release file."
}

running_distribution=$(distro_version) || exit $?

and the case switches:

case " $running_distribution " in
    *\ @(ubuntu|debian)\ *)
        echo "Matching debian" ;;
    *\ pop\ *)
        echo "Matching pop!_os" ;;
    *)
        echo "no match!" ;;
esac

If you want to just match from the beginning of ID, ID_LIKE as it is now, probably simpler to cast ID_LIKE to an array first:

ID_LIKE=($ID_LIKE); echo "${ID_LIKE[0]:-$ID}"

that would remove the need for word* wildcard matching:

case "$running_distribution" in
    ubuntu|debian) echo match ;;
esac