on.exit for scripts

on.exit2

# on.exit for scripts, on.exit2 will create, update or overwrite 
# the object .on.exit.exprs (of class expression) in the calling environment
# at the end of the script we evaluate .on.exit.exprs
on.exit2 <- function(expr = NULL, add = FALSE, after = TRUE){
  if(!exists(".on.exit.exprs", parent.frame())) 
    assign(".on.exit.exprs",expression(), envir = parent.frame())
  if(add){
    if(after)
      .on.exit.exprs <<- c(.on.exit.exprs, substitute(expr))
    else
      .on.exit.exprs <<- c(substitute(expr),.on.exit.exprs)
  } else {
    .on.exit.exprs <<- as.expression(substitute(expr))
  }
}
# then as the last line of the script
eval(.on.exit.exprs)

To go further:

exit.script <- function() {
eval.parent(.on.exit.exprs)
rm(".on.exit.exprs", envir = parent.frame())
}