title: How to overwrite environment variables in mac using Shell Script
body: <p>I have a set of environment variables that need to be set on the basis of the arguments specified in the shell script. 
  But the problem is that those variables are already defined in the bash profile
  FOR EXAMPLE: </p>
  
  <p>bash_profile has a variable called "KARAN":
  export KARAN=/config/1</p>
  
  <p>Now on running the shell script, this is what it should do:
  export KARAN=/config/2 (Changed the bash profile's KARAN value to 2)</p>