dia-libs software package provides Diagram editor (library files), 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 dia-libs
dia-libs is installed in your system.
Make ensure the dia-libs package were installed using the commands given below,
$ sudo dpkg-query -l | grep dia-libs *
You will get with dia-libs package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | Graphics |
| Package | dia-libs |
| Version | 0.97.3-1 |
| Description | Diagram editor (library files) |
| Sub Section | Graphics |