How to run psql script in the background?

#!/bin/bash

CURRENTDATE=`date +"%Y%m%d_%H%M%S"`

OUTPUT_FILE="./outp/trace_${CURRENTDATE}.out"

export PGPASSWORD='********'

nohup psql -h my_hostname -U my_db_user -d my_db_name -a -f my_sql_script.sql > ${OUTPUT_FILE} 2>&1 < /dev/null &