$(date +%F)

$(date +%Y%m%d)

$(date +%Y%m%d%H%M%S)

date --date "3 days ago" +%F

date --date "3 days" +%F

for d in $(seq 0 400); do day=$(date --date "$d days ago" +%Y%m%d)0000; touch -t ${day} ${day}; done