It examines the settings in the host environment for any environment variables that may apply to the runtime. Environment variables are values maintained by the host operating system that can be changed by the user. They can be set in the autoexec.bat file, or in a .login or .profile file. Using one of these files to set environment variables ensures that the variables are set for a particular user for each session. Otherwise they can be set for a single session for a one-time use only.
Filenames are almost always lower case.
The exact syntax to set environment variables depends on the operating system and shell that is being used. Many different types of terminals are used with the UNIX operating system. Each terminal type requires different control sequences to set video attributes and position the cursor. Each entry in the termcap file consists of the name of a terminal type, followed by its screen and keyboard attributes and definitions. Configuration variables can be set in the host environment.