#Friday13th
y1="${1:-$(date +%Y)}"
y2="${2:-$y1}"
for i in $(seq "$y1" "$y2"); do
for j in $(seq 1 12); do
test $(date -d "$i-$j-13" +%a) = 'Fri' && \
printf '%04d-%02d-13\n' "$i" "$j"
done
done
WATCH: 'We are very concerned about him.' The health of the world’s last male northern white rhino has deteriorated, bringing the subspecies a step closer to extinction. https://t.co/FOBgruKbe4