The original title reads "... for your Unix shell", suggesting that the code is portable to many shells. I have not verified that claim. "... for the Unix shel

The original title reads "... for your Unix shell", suggesting that the code is portable to many shells. I have not verified that claim. "... for the Unix shell" makes little sense. When I used Unix my shell was csh, later tcsh. Nowadays my shell is bash in most cases and dash in some more limited environments. Either case, "the Unix shell" does not exist.