envvars file

The Apache2 environment variables are set in the /etc/apache2/envvars file. These variables are not the same as the environment variables of your Linux system; they are stored and manipulated in an internal Apache structure.

The /etc/apache2/envvars file holds variable definitions such as APACHE_LOG_DIR (the location of Apache log files), APACHE_PID_FILE (the Apache process ID), APACHE_RUN_USERS (the user that run Apache, by default www-data), etc.

You can open and modify this file in a text editor of your choice: