Environment variable in Mac OS X

What is environment variable?

--> Environment variable is an array of string type having the form of "name=value", which is a simple way to provide multiple applications and processes with the same configuration of a particular setting in operating system level.

Environment variable can be user-specific, which means different users may have different "name-value" pairs of their own. Typing the command "man 7 environ", environment variables of the current user of this machine are prompted on the terminal. 

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