Repeat Linux command every x seconds

watch -n 5 "ps -ef | grep COPY"

watch -n 10 "psql -U postgres -c \"select clock_timestamp() - query_start as duration, substr(query,1,50) from pg_stat_activity where pid <> pg_backend_pid() and state='active' order by 1 desc\""

for i in {1..10}; do ps -ef | grep COPY; date ; sleep 5; done

while true; do ps -ef | grep COPY ; date ; sleep 5; done