libxau6 software package provides X11 authorisation library, you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install libxau6
libxau6 is installed in your system.
Make ensure the libxau6 package were installed using the commands given below,
$ sudo dpkg-query -l | grep libxau6 *
You will get with libxau6 package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | Libraries |
| Package | libxau6 |
| Version | 1:1.0.8-1 |
| Description | X11 authorisation library |
| Sub Section | libs |