Good point! Both of them. That would make a not-so-quick but better hack. Append a timestamp and a start note / end note with exit code to a log file, to have a history. You might also send an email in case of a crash. Let's see ...

#!/bin/sh
while true
do
  start_your_program
  RC=$?          # return code
  if [ $RC -gt 0 ]
  then
    date >> /var/log/your_log_file
    echo "ABNORMAL program termination, rc = $RC" >> /var/log/your_log
+_file
    echo "terminated at `date`, restarting | mail -s "Problem with zzz
+" root
    sleep xxx
  else
    date >> /var/log/your_log_file
    echo "Normal program termination, rc = $RC" >> /var/log/your_log_f
+ile
    sleep yyy
  fi
done
[download]

You can do further checking on the exit code as Mark suggested and act diffently according to the exit code (see case statement in your shell manual).

Andreas