Answer :
Use the env command to see your current environment variables. A global variable is an environment variable that is available to all of your processes.
The environment variables in the current shell are displayed using the printenv command-line tool. Printenv is the most used command for displaying environment variables. Only that variable's value is displayed if the variable's name is supplied as an argument to the command. Printenv prints a list of all environment variables, one variable per line, if no argument is given. The best method for proving that two variables are causally related is to utilize a controlled study. In a controlled study, the sample or population is divided into two groups that are nearly identical in every way.
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