insserv binary package in Ubuntu Xenial amd64

 The insserv program is used by the standard SysV-based init system. It
 updates the order of symlinks in /etc/rc?.d/ based on dependencies
 specified by LSB headers in the init.d scripts themselves.
 .
 These declared relations between scripts make it possible to optimize
 the boot sequence for the currently installed set of packages, while
 detecting and rejecting dependency loops.
 .
 Using insserv incorrectly can result in an unbootable system.

Source package