Shell Programming and Scripting

integer n=0
while ((n <= 18));
do
     if [[ -e filename ]]
          then
               integer n=19
          else
               if [[ n = 18 ]]
                    Send your mail with whatever command you need....
               else
                    sleep 600
               fi
     fi
n++
done

#!/bin/sh
: your code here # you would need a counter to end (see above thread of treesloth) 
                      # and mail after 3 hours of unsuccessfull attempts...etc..

echo "$0" "$@" | at now + 10 minutes

while (( $i <= 60 ))
do
  if [ -f $File ]
  then
      echo "File Found"
      break
  else
      sleep 10
      i=`expr $i + 10`
      if [ $i -gt 60 ]
      then
          echo "ALERT!!" | mailx -s "ALERT!!" ${ID}
      else
          sleep 1
      fi    
  fi
done