pmx software package provides Preprocessor for MusiXTeX, 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 pmx
pmx is installed in your system.
Make ensure the pmx package were installed using the commands given below,
$ sudo dpkg-query -l | grep pmx *
You will get with pmx package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | TeX |
| Package | pmx |
| Version | 2.7.0.ctan20131214-1 |
| Description | Preprocessor for MusiXTeX |
| Sub Section | TeX |