latex-cjk-thai software package provides Thai module of LaTeX CJK, 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 latex-cjk-thai
latex-cjk-thai is installed in your system.
Make ensure the latex-cjk-thai package were installed using the commands given below,
$ sudo dpkg-query -l | grep latex-cjk-thai *
You will get with latex-cjk-thai package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | TeX |
| Package | latex-cjk-thai |
| Version | 4.8.3+git20120914-2ubuntu1 |
| Description | Thai module of LaTeX CJK |
| Sub Section | TeX |