Environment variables are a must use tool for developers, here is a easy list of commands you will need to know.

What are environment variables?
Environment variables can be thought of as global variables that can be accessed by different applications. Imagine if several applications were using a shortcut key for your desktop, they could and would use an environment variable that pointed to your desktop which could be easily updated if need be. Environment variables don't have to be paths, they can store other data.

Retrieve list of existing environment variables
printenv - shows all environment variable
set - show complete list of shell variables

Retrieve a specific environment variable
echo $NAME

Set environment variables
touch ~/.bash_profile // creates a file if it doesn't exist

nano ~/.bash_profile // opens the bash_profile file in terminal
// or open like this
open ~/.bash_profile // opens the bash_profile file using a text editor

export VARIABLE_NAME=data // set/update environment variable

source ~/.bash_profile // run bash_profile file

Update environment variable
same as setting an environment variable

Delete environment variable
touch ~/.bash_profile // creates a file if it doesn't exist

nano ~/.bash_profile // opens the bash_profile file in terminal
// or open like this
open ~/.bash_profile // opens the bash_profile file using a text editor

unset VARIABLE_NAME // deletes environment variable

source ~/.bash_profile // run bash_profile file