Shell Programming and Scripting

# Contained test of principal
#
cnt=0
while [ $cnt -lt 600 ]
 do
    while [ $cnt -lt 300 ]
     do
      echo .
      ping -c 3 not_connected_IP>>/tmp/pinglog$$.txt
      sleep 13
      ((cnt=cnt+15))
     done

    while [ $cnt -lt 300 ]
     do
      echo -n "Minutes since start = " > divres
      echo "scale=2; $cnt/60" | bc >> divres
      if cat divres | grep .00
       then
        echo
        cat divres
      fi
     done
 done
rm -r /tmp/pinglog$$.txt

cnt=0
while [ $cnt -lt 600 ]
 do

    while [ $cnt -lt 300 ]
     do
      echo .
      # Instead of opening pinglog$$.txt n/15 times, redirect the
      # while loop itself, so you only open it once.
      ping -c 3 not_connected_IP#>>/tmp/pinglog$$.txt
      sleep 13
      ((cnt=cnt+15))
      # Jumps back up to the top of the loop if cnt is less than 300.
     done >> /tmp/pinglog$$.txt

    # to reach here, the while loop must have ended.  Therefore, 
    # cnt is already >= 300.  So this next while loop never happens.
    while [ $cnt -lt 300 ]
     do
      echo -n "Minutes since start = " > divres
      echo "scale=2; $cnt/60" | bc >> divres

#      this is a Useless Use of Cat.  http://partmaps.org/era/unix/award.html
#      grep doesn't need cat's help.
#
#      You should also use grep -q so grep doesn't try print matching lines.
#      Also:  Are you trying to match a literal dot?  dots mean 'any character'
#      grep.  Escape it with a backslash to make it match only the dot char.
#      if cat divres | grep .00
       if grep -q "\.00" < divres
       then
        echo
        cat divres
      fi
     done

     # Loops back to the beginning of the first while loop whenever
     # cnt is less than 600.
     # But cnt will never be greater than 300 because your inner
     # while loops stop doing anything past 300.
     # so this becomes an infinite loop!
 done
rm -r /tmp/pinglog$$.txt

ping -w 15 -f mysite.com