errors in Configuring DruTeX Input formats

I just installed the DruTeX module.
Do I need a TeX distribution installed in the server to get a dvi preview?
If I misunderstand how the module works, would anyone tell me if there are any demo pages telling users how to render source code in a page and how the output is shown?

Administer › Site configuration › Input formats › DruTeX
This shows multiple lines of errors.

* warning: exec() has been disabled for security reasons in /home/vol3/gofreeserve.com/gofre_4188226/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 89.
* warning: exec() has been disabled for security reasons in /home/vol3/gofreeserve.com/gofre_4188226/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 107.
* warning: exec() has been disabled for security reasons in /(I omit)/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 125.
* warning: exec() has been disabled for security reasons in /(I omit)/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 89.
* warning: exec() has been disabled for security reasons in /(I omit)/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 107.
* warning: exec() has been disabled for security reasons in /(I omit)/htdocs/home/modules/autoload/drutex/drutex_tools.inc on line 125.

I assume LaTeX users may think the simple code like below should produce an appropriate output easily.

\documentclass{article}
\begin{document}
\TeX!
\end{document}

I tried the version containing following lines only.
\int \ln(x) \;dx
&= \int 1 \cdot \ln(x) \;dx \
&= x \cdot \ln(x) - \int x \cdot \frac{1}{x} \;dx \
&= x \cdot \ln(x) - x
But it did not work.

Thank you.