com grep - egrep -o "[0-9]+ days"
(your nstats command) | sed -n '2p' | egrep -o "[0-9]+ days"
22 days
com awk - awk '{print $14,$15}'
(your nstats command) | sed -n '2p' | awk '{print $7,$8}'
22 days
Com awk (apenas os dias) - awk '{print $14}'
(your nstats command) | sed -n '2p' | awk '{print $7}'
22