[SOLVED] Unix string to date conversion, what is wrong

Issue

I know the topic has already emerged and some of the posts give a good summary like the one here: Convert string to date in bash . Nevertheless, I encounter a problem presented below with an example I should solve:

date +'%d.%m.%y' works as desired and returns 05.12.20 but the inverse operation I should use to convert strings to date fails:

date -d "05.12.20" +'%d.%m.%y'
date: invalid date ‘05.12.20’

and this is exactly what I need. The Unix date formatting I have also checked on https://www.cyberciti.biz/faq/linux-unix-formatting-dates-for-display/ but it seems to be in line with that. What is the problem? I also tried to supply time zone indicators like CEST but they did not solve the problem.

Solution

Try

date -d "05-12-20" +'%d.%m.%y'

UNIX date expects either - or / as a date separator.

However, if your input really must be in the format "05.12.20" (i.e. using .), then you can convert it to the format expected by UNIX date:

date -d `echo "05.12.20" | sed 's/\./-/g'` +'%d.%m.%y'

Answered By - costaparas