systemd/systemd-sysv-install

#!/bin/sh
# This script is called by "systemctl enable/disable" when the given unit is a
# SysV init.d script. It needs to call the distribution's mechanism for
# enabling/disabling those, such as chkconfig, update-rc.d, or similar. This
# can optionally take a --root argument for enabling a SysV init script
# in a chroot or similar.
set -e

usage() {
    echo "Usage: $0 [--root=path] enable|disable|is-enabled <sysv script name>" >&2
    exit 1
}

# parse options
eval set -- "$(getopt -o r: --long root: -- "$@")"
while true; do
    case "$1" in
        -r|--root)
            ROOT="$2"
            shift 2 ;;
        --) shift ; break ;;
        *) usage ;;
    esac
done

NAME="$2"
[ -n "$NAME" ] || usage

case "$1" in
    enable)
        chkconfig $ROOT --no-systemctl -s "$NAME" on
        ;;
    disable)
        chkconfig $ROOT --no-systemctl -s "$NAME" off
        ;;
    is-enabled)
        chkconfig $ROOT --no-systemctl -c "$NAME"
        ;;
    *)
        usage ;;
esac