run the script with nohup in background

#!/bin/ksh
DATE=$(date +%m%d%y)
DPID=$(ps -ef|grep str_process_main|grep -v grep)
if [ "${DPID}" = "" ]; then
cd /usr/local/wss_polling
nohup str_process_main &
echo "The process was not running."
else
echo "The process is already running: $DPID."
fi
exit