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Old March 11th 19, 08:32 PM posted to alt.windows7.general
pyotr filipivich
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Posts: 752
Default Did Miscrosoft change how it dates files?

Stan Brown on Mon, 11 Mar 2019 12:05:59
-0400 typed in alt.windows7.general the following:
On Sun, 10 Mar 2019 22:23:09 -0700, pyotr filipivich wrote:

Greetings

I have a batch file using Robocopy which is only suppose to copy
those files which are "newer" (I.e., modified) than the ones on the
drive. Usually, there is no problem. But tonight, as I go to close
up operations for the evening, it is copying far more files than
before. all tagged "newer".
Was there something magical about the shift to Daylight Savings
time which makes a source drive file dated "Jan 2 2019 10:20 AM" to
now be "newer" than the target drive file dated "Jan 2 2019 10:20
AM"?


If you use the /TS option, robocopy will show you the timestamps of
the source file. When the source file is on an NTFS drive, that will
be in UTC, not your local time. (The timestamps displayed in File
Explorer are converted from the NTFS native UTC to your time zone.)

When the source file is on a FAT or FAT32 drive, native time is the
local time zone when the file was created or modified. (I can't
remember whether robocopy shows that local time, or converts it to
UTC.) That means if you create a file on a FAT32 USB stick at
10:00:00 Eastern Standard Time, and then mount it in Eastern Daylight
Time, the timestamp will show in File Explorer as 10:00:00, even
though the file was created at 9:00:00 Easter Daylight Time.

Robocopy supposedly understands the semiannual daylight-time shift,
and doesn't copy files in such cases, but I don't know how it knows.
I just make sure that I have updated my USB stick the last thing
before going to bed the night before the shift, so that even if the
timestamps are wrong the file contents are correct.

This past weekend, after the time shift, out of hundreds of Eastern
Standard Time files on my USB stick, robocooy wanted to copy exactly
four. I don't know what made those different from the others, so I
don't know if robocopy does basically compensate for DST and just
failed with these four.

There is an option in robocopy to copy the timestamp of a file
without copying the file contents. You might want to use that, come
November.


Thanks, I will look into that.

I'm already trying to remember the hack I had so that after it
ran, it then shut the computer off "for the night".
--
pyotr filipivich
Next month's Panel: Graft - Boon or blessing?
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