date -d '1970-01-01 UTC 946684800 seconds' +"%Y-%m-%d %T %z"
start_time=`date -d "1970-01-01 UTC $date_start seconds" +"%Y-%m-%d %H:%M:%S"`;
date -d '1970-01-01 UTC 946684800 seconds' +"%Y-%m-%d %T %z"
start_time=`date -d "1970-01-01 UTC $date_start seconds" +"%Y-%m-%d %H:%M:%S"`;