• To create Shell variables (Shell variables means only accessible within the shell script)

  TEST_VAR='Hello World!'
  

• To make shell vraibles as Environemnet variables (Environment Variables are accesible to child process)

  export TEST_VAR
  

• To create new Environment variables (Once the shell is closed the environment variables are destroyed. And the child process environment variables cannot be accessed by parent)

  export NEW_VAR="Testing export"
  

• To see the environment variables

  printenv
  printenv variable_name (To print the environment variable value)
  

• To list all shell variables, environmental variables, local variables, and shell functions

  set
  

• To change Environment variable to shell variable

  export -n TEST_VAR
  

• If we want to completely unset a variable, either shell or environmental

  unset TEST_VAR