Once installed Magento in Ubuntu and noticed in the browser the following error:
There were also pieces of code, depending on the open page.
In my case, the error occurred because of the uninstalled libapache2-mod-php, installed it with the command:
sudo apt-get install libapache2-mod-php
After that the error did not appear and I continued the installation of Magento.
Thanks for sharing all of your experiences!