Ubuntu and Gentoo cross-compatible implementation of Command Not Found snippet

gentoo-cnf.bash

# if the command-not-found package is installed, use it
if [ -x /usr/lib/command-not-found ] || [ -x /usr/share/command-not-found/command-not-found ]; then
    function command_not_found_handle() {
        # check because c-n-f could've been removed in the meantime
        if [ -x /usr/lib/command-not-found ]; then
            /usr/lib/command-not-found -- "$1"
            return $?
        elif [ -x /usr/share/command-not-found/command-not-found ]; then
            /usr/share/command-not-found/command-not-found -- "$1"
            return $?
        else
            printf "%s: command not found\n" "$1" >&2
            return 127
        fi
    }
elif [ -x /usr/bin/e-file ]; then # e-file is provided by app-portage/pfl and does exactly what we need.
    function command_not_found_handle() {
        # Command may have disappeared since the definition of this function
        if [ -x /usr/bin/e-file ]; then
            echo "Trying to find package providing this command..."
            result=$(/usr/bin/e-file "$1")
            if [ -z "$result" ]; then
                echo "$0: $1: command not found"
            else
                echo "$result"
            fi
            #/usr/bin/qfile "$1"
            return $?
        else
            printf "%s: command not found\n" "$1" >&2
            #echo "$1: command not found"
            return 127
        fi
    }
else
    echo "To try to find the package providing this command, please install app-portage/pfl (Gentoo) or command-not-found (others)"
fi

gentoo-cnf.zsh

# if the command-not-found package is installed, use it
if [[ -x /usr/lib/command-not-found ]] || [[ -x /usr/share/command-not-found/command-not-found ]]; then
    function command_not_found_handler() {
        # check because c-n-f could've been removed in the meantime
        if [[ -x /usr/lib/command-not-found ]]; then
            /usr/lib/command-not-found -- "$1"
            return $?
        elif [[ -x /usr/share/command-not-found/command-not-found ]]; then
            /usr/share/command-not-found/command-not-found -- "$1"
            return $?
        else
            printf "%s: command not found\n" "$1" >&2
            return 127
        fi
    }
elif [ -x /usr/bin/e-file ]; then
    function command_not_found_handler() {
        # Command may have disappeared since the definition of this function
        if [[ -x /usr/bin/e-file ]]; then
            echo "Trying to find package providing this command..."
            result=$(e-file $1 2>/dev/null)
            #echo "result: $result"
            if [[ "$result" == "No matches found." ]]; then
                echo "zsh $1: command not found"
            else
                echo "$result"
            fi
            return $?
        else
            echo "please re-emerge app-portage/pfl to restore this functionality"
            return 127
        fi
    }
else
    echo "To try to find the package providing this command, please install app-portage/pfl (Gentoo) or command-not-found (others)"
fi

Add to rc file, or source it