#!/bin/bash
if [ "$#" -eq "0" ] || [ "$1" == "-?" ]; then
  echo "Usage: `basename $0` sleeptime frequency [message]"
  echo "Sleep for <sleeptime>, notify every <frequency>"
fi
SLEEPTIME=$1
FREQUENCY=$2
shift 2
MESSAGE=$@

echo "`date` $MESSAGE"

# Start the main sleep process
sleep "$SLEEPTIME" &
# Note its PID
SLEEP_PID=$!

while :
do
  sleep $FREQUENCY
  echo "`date` $MESSAGE"
done &
# The while loop runs in its own subshell, and
# has its own PID. Make a note:
LOOP_PID=$!

# Kill the loop if we exit for any reason
trap 'kill -9 $LOOP_PID' 0

# Wait for the main sleep to finish
wait $SLEEP_PID

# Finished.
echo "`date` $MESSAGE : Done."
#kill -9 $LOOP_PID