#!/bin/bash
# define interval(seconds) after which you want the script to wake up
interval=180
sleep 1000
# start infinite loop
while [ 1 ]
do
# first sleep interval seconds
sleep ${interval}
# next check condition on which you want VASP to stop
./check_hcl
grep "E0= " OSZICAR | tail -n 1 | awk '{print $9}' >> trajectory.dat 
done