Unix: Increment date column by one day in csv file - unix

Question

Help needed. I want to increment Date (which is a string) column in csv by one day.
e.g. (Date Format yyyy-MM-dd)
Col1,Col2,Col3
ABC,001,1900-01-01
XYZ,002,2000-01-01
Expected OutPut
Col1,Col2,Col3
ABC,001,1900-01-02
XYZ,002,2000-01-02

Answer 1

There's one standard Unix utility that has all the date magic from September 14, 1752 through December 31, 9999 built-in: the calendar cal. Instead of reinventing the wheel and do messy date calculations we will use its intelligence to our advantage. The basic problem is: given a date, is it the last day of a month? If not, simply increment the day. If yes, reset day to 1 and increment month (and possibly year).
However, the output of cal is unspecified and it may look like this:
$ cal 2 1900
February 1900
Su Mo Tu We Th Fr Sa
1 2 3
4 5 6 7 8 9 10
11 12 13 14 15 16 17
18 19 20 21 22 23 24
25 26 27 28
What we would need is a list of days, 1 2 3 ... 28. We can do this by skipping everything up to the "1":
set -- $(cal 2 1900)
while test $1 != 1; do shift; done
Now the number of args gives us the number of days in February 1900:
$ echo $#
28
Putting it all together in a script:
#!/bin/sh
read -r header
printf "%s\n" "$header"
while IFS=,- read -r col1 col2 y m d; do
case $m-$d in
(12-31) y=$((y+1)) m=01 d=01;;
(*)
set -- $(cal $m $y)
# Shift away the month and weekday names.
while test $1 != 1; do shift; done
# Is the day the last day of a month?
if test ${d#0} -eq $#; then
# Yes: increment m and reset d=01.
m=$(printf %02d $((${m#0}+1)))
d=01
else
# No: increment d.
d=$(printf %02d $((${d#0}+1)))
fi
;;
esac
printf "%s,%s,%s-%s-%s\n" "$col1" "$col2" $y $m $d
done
Running it on this input:
Col1,Col2,Col3
ABC,001,1900-01-01
ABC,001,1900-02-28
ABC,001,1900-12-31
XYZ,002,2000-01-01
XYZ,002,2000-02-28
XYZ,002,2000-02-29
yields
Col1,Col2,Col3
ABC,001,1900-01-02
ABC,001,1900-03-01
ABC,001,1901-01-01
XYZ,002,2000-01-02
XYZ,002,2000-02-29
XYZ,002,2000-03-01
I made one little assumption: The first two columns don't contain a - or escaped comma. If they do, the IFS=,- read will act up.

Answer 2

Using the date command, this can be done in awk:
awk 'BEGIN{FS=OFS=","}NR>1{("date -d\""$3" +1 day\" +%Y-%m-%d")|getline newdate; $3=newdate; print}' file.in

Answer 3

If you can extract the date from the file, you can use this:
d="1900-01-01" # date from file
date --date '#'$(( $(date --date $d +"%s") + 86400 ))