02/02/2020! The first palindrome date since 11/11/1111

It's been almost a decade since I've seen an "only happens every several hundred years" thing floating around that seemed too out-there to be real.

So let's debunk the "first palindrome date since 11/11/1111" shall we? Surely these happen more frequently than that. And for shame not using ISO-8601 format. Fortunately, today also works as an ISO-8601 palindrome: 2020-02-02.

I whipped up a quick bash script to scan for dates n-days before and after today's date looking for palindromes in ISO-8601 format as well as the two other formats that are commonly (ab)used here in the United States, DD-MM-YY and DD-MM-YYYY. It's inefficient, relying on a lot of calls to date(1) and rev(1) but it is what it is.

#!/bin/sh

export i=1

while true

do

# ISO-8601 or GTFO.

idtb=`date -v-${i}d +%Y%m%d`

idtf=`date -v+${i}d +%Y%m%d`

# MM-DD-YYYY format

ydtb=`date -v-${i}d +%m%d%Y`

ydtf=`date -v+${i}d +%m%d%Y`

# MM-DD-YY format

dtb=`date -v-${i}d +%m%d%y`

dtf=`date -v+${i}d +%m%d%y`

if [ "$idtb" -eq "`echo $idtb | rev`" ]

then

echo YYYYMMDD $idtb was a palindrome.

fi

if [ "$idtf" -eq "`echo $idtf | rev`" ]

then

echo YYYYMMDD $idtf will be a palindrome.

fi

if [ "$ydtb" -eq "`echo $ydtb | rev`" ]

then

echo MMDDYYYY $ydtb was a palindrome.

fi

if [ "$ydtf" -eq "`echo $ydtf | rev`" ]

then

echo MMDDYYYY $ydtf will be a palindrome.

fi

if [ "$dtb" -eq "`echo $dtb | rev`" ]

then

echo MMDDYY $dtb was a palindrome.

fi

if [ "$dtf" -eq "`echo $dtf | rev`" ]

then

echo MMDDYY $dtf will be a palindrome.

fi

export i=`expr $i + 1`

done

A quick run for a minute or so shows a lot of palindromes past and future.

MMDDYY 021120 will be a palindrome.
MMDDYY 022220 will be a palindrome.
YYYYMMDD 20211202 will be a palindrome.
MMDDYYYY 12022021 will be a palindrome.
MMDDYY 121121 will be a palindrome.
MMDDYY 122221 will be a palindrome.
MMDDYY 112211 was a palindrome.
MMDDYY 111111 was a palindrome.
YYYYMMDD 20111102 was a palindrome.
MMDDYYYY 11022011 was a palindrome.
MMDDYY 012210 was a palindrome.
MMDDYY 011110 was a palindrome.
YYYYMMDD 20300302 will be a palindrome.
MMDDYYYY 03022030 will be a palindrome.
YYYYMMDD 20100102 was a palindrome.
MMDDYYYY 01022010 was a palindrome.
MMDDYY 031130 will be a palindrome.
MMDDYY 032230 will be a palindrome.