dracut-core software package provides Low-level tool for generating an initramfs image (core tools), you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install dracut-core
dracut-core is installed in your system.
Make ensure the dracut-core package were installed using the commands given below,
$ sudo dpkg-query -l | grep dracut-core *
You will get with dracut-core package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Utilities |
| Package | dracut-core |
| Version | 044+3-3 |
| Description | Low-level tool for generating an initramfs image (core tools) |
| Sub Section | Utils |