On 10/28/19 12:34 AM, zhangzhi...@mail.iap.ac.cn wrote:
~>date -d "1940-06-01" +"%Y-%m-%d"
date: invalid date ‘1940-06-01’
Presumably your TZ setting is Asia/Shanghai, as I see the symptoms as
follows:
$ TZ=Asia/Shanghai date -d "1940-06-01" +"%Y-%m-%d"
date: invalid date ‘1940-06-01’
This is because there is no instant of time 1940-06-01 00:00:00 in
Shanghai, as the the clock ticked over from 1940-05-30 23:59:59 to
1940-06-01 01:00:00 due to a daylight-saving time transition.
For this particular case, you'll have better luck with:
$ date -d "1940-06-01 12:00" +"%Y-%m-%d"
but this sort of approach does not work in general, because 12:00 does
not always exist either. In other words, the 'date' command is not
suited for calendrical arithmetic in general, only for time arithmetic.
