Using Environment Variables
A number of in-memory variables are assigned and loaded by default when you log in. These variables are known as environment variables and can be used by various commands to get information about your environment, such as the type of system you are running, your
/home directory, and the shell in use. Environment variables are used to help tailor the computing environment of your system and include helpful specifications and setup, such as default locations of executable files and software libraries. If you begin writing shell scripts, you might use environment variables in your scripts. Until then, you need to be aware only of what environment variables are and do.
The following list includes a number of environment ...