Set EnvironmentVariables in MacOS

* Check Environment Variables

# list all environment variables
$ printenv 

# list one specific variable PATH
$ echo $PATH

* Set Permanent Environment Variable

1. Find or create ~/.bash_profile

# list exist .bash_profile 
$ ls -la ~/.bash_profile

# create one if not exist
$ vim ~/.bash_profile

2. Open ~/.bash_profile and add the following line at the end of the file

# export [variable_name]=[variable_value]

$ export OPEN_AI_KEY="sk-"

$ PATH="~/bin:${PATH}"
$ export PATH

save any changes to ~/.bash_profile

3. Either restarting the terminate window or running

source ~/.bash_profile