POSIX and strftime

I'd suggest Time::Piece instead, it's been a core module since 5.10.

<update>

$ perl -MTime::Piece -le 'print localtime->strftime("%Y.%m.%d.%H%M")'
2019.08.01.2239
[download]

</update>

DateTime::Format

Note that link goes to a defunct module, you probably meant the DateTime::Format::* family of modules instead. But plain DateTime has both strftime and CLDR formatting built right in, that's generally been enough for me (I usually parse with DateTime::Format::Strptime).