Danny Ayers is looking for a shell script to keep another process alive. I'm sure I won't do better... I do as little shell scripting as possible. Shell programming never seemed aimed at humans.
Everything I've wanted to do manually in a shell script I have done more easily in Emacs or some other interactive programming environment involving Lisp or Smalltalk. For automated tasks its as easy to schedule a Lisp script as easily as bash. The trick in the past was using a small Lisp like XLisp or one that generates small apps like Gambit Scheme. That's still the trick but there are more choices.
Many Lisp implementations these days understand the #! notation to run as a script. Another option is to use scsh, the Scheme Shell.