Shell Programming and Scripting

echo $TZ
NFT-1DFT,M3.5.0/02:00:00,M10.5.0/03:00:00

#! /bin/bash
start=`date +"%s"`
while [ `date +"%s"` -ne `expr $start + 10800` ]
do
    echo "Hello"
    sleep 1
done

#!/bin/ksh
# usage: sleeperagent.ksh <flagfile> <timeinseconds>
[ ! -f $1 ] && sleep $2   # flagfile should not exist when we start sleeping
touch $1

...
flagfile=/tmp/$$.flag
/path/to/sleeperagent.ksh $flagfile 10800 &  # 10800 seconds = 3 hours
while [ ! -f $flagfile ]; do
...
done
rm $flagfile
...

#!/bin/bash

test $# -ne 2 && echo "Usage : killer_script <pid> <time_secs>" && exit 0                      
pid_to_kill=$1
time_to_die=$2
sleep $time_to_die
kill -9 $pid_to_kill

#!/bin/bash

./killer_script $$ 10800 &

#do your stuff and the killer will kill this script after the specified time

echo "touch /tmp/exitflagfile" | at now +3 hours

while whatever
do
     [ if -f /tmp/exitflagfile ]
     then
            rm /tmp/exitflagfile
            exit
     fi
     # Rest of script
done