how to start a process and make it sleep for 5 mins and then kill that process

write a script and give sleep function in that.call it with background process by running

scriptname &

while [ 0 -le 5 ] #which is infinite while loop
do
./my_function_which_prints_hi_every_5secs #written in C & stored
sleep 10
killall -9 ./my_function_which_prints_hi_every_5secs #shuld kill program
done

scriptname &; sleep 300; kill $!

I tried this method,still I am getting no process killed. can you justhelp in this
I=1
while [ $I -le 2 ]
do
scriptname &
sleep 10
killall -9 scriptname
echo $I
I=`expr $I + 1`
done

do_something &
sleep 300
kill $!

you havent used kill $! to kill the last background process
use that !

instead of use

kill $!