The behaviour of LibGGI can be altered by setting various environnemnt variables. This allow the user to choose a target display, specify a default mode for ggi applications, enable or disable inputs.
There are two kinds of environment variables in GGI: those which defined as the global level, such as the requested target or default mode, and those which are specific to a particular input or target modules. The general environment variables are detailed in the libgii and libggi reference pages. You should refer to your modules reference to know which specific environment variables are defined.
In the UNIX world, setting an environment variable is achieved on the command line using setenv or export, depending on your shell.
Example 4-1. Setting env on a csh-like shell
user@cshlikeshell / > setenv MYENVVAR "its value" user@cshlikeshell / > echo $MYENVVAR its value
Example 4-2. Setting env on a bash-like shell
user@bashlikeshell / > export MYENVVAR="its value" user@bashlikeshell / > echo $MYENVVAR its value
You can add these lines to your profile to avoid retyping them every time.
Keep in mind however that these are just default settings for applications, which can be bypassed. Although it should be avoided whenever possible, the developer may have hardcoded certain values in a given application, forcing it to run in 640x480 mode for example, regardless of the user settings.
TODO.