Usage
## S3 method for class 'default}(fcn, action=c("prepend", "append", "replace"), ...)':
onSessionExitundefined
- fcn{A
function to be called without argument.}
 - action{A
character string specifying how the hook function is
   added to list of hooks.}
 - ...{Not used.}
Returns (invisibly) the hooks successfully called.
Functions registered this way are called when finalizeSession() is
  called.  Moreover, when this package is loaded, the .Last()
  function is modified such that finalizeSession() is called.
  However, note that .Last() is not guaranteed to be called
  when the Rsession finished.  For instance, the user may quit Rby
  calling quit(callLast=FALSE).
  Moreover, when Ris run in batch mode, .Last() is never called. 
[object Object]
onSessionExit(function(...) {
    cat("Bye bye world!\n");
  })
  quit()
.Last().
  finalizeSession().
programming