I just synthesized a small piece of code which may be of use to beginners and intermediate users.
This code upon execution sets the current working directory to that of the notebook from which it is run. This may be useful when a notebook is shifted from one place to another and it reads an input data file.
I know it is a ''piece of cake'' for pros in Mathematica, but for beginners like me it is a god sent routine.
I request the moderator to post it in the appropriate place.