Rules for “Date Modified” of folders in Windows Explorer

问题

How does Windows Explorer determine the "Date Modified" field for folders? [Aside: I know this is asking from an explorer-specific perspective, but the behaviour could be useful to coding search/sort type activities]

Is there a definitive description of this anywhere - searches of Microsoft, MSDN, Google & Stack Overflow have been unsuccessful.

Personal experiments seem to suggest that in a tree of folders:

when a folder/file is added/deleted in a folder, the containing folder's date modified is updated.
when the content of a file is modified, the containing folder is unaffected

However, I'm looking at some directories that don't seem to conform to these basic rules - running down the tree I have (dates in DD/MM/YYYY format):

folder     (date created:  2/2/2006, date modified: 2/3/2006)
  folder   (date created:  2/2/2006, date modified: 2/3/2006)
    folder (date created:  2/2/2006, date modified: 1/6/2009)
      file (date created: 27/3/2009, date modified: 2/2/2006)

回答1:

This is not explorer specific, this is NTFS-related.

See ~~http://support.microsoft.com/kb/299648~~ https://web.archive.org/web/20080219020154/http://support.microsoft.com/kb/299648 for some rules.

Note: Modified time can be disabled with filesystem option, so you should never rely on it. Any suggested reliable methods would be appreciated.

回答2:

Disclaimer: I tested all of these myself on Windows 10. I could not find an authoritative source documenting all of these behaviours. It is entirely possible that I made a mistake somewhere.

The folder's last modified time is updated for these actions:

new file or folder directly in target folder
renamed file or folder directly in target folder
deleted file or folder directly in target folder
hardlink create/delete/rename - same as files
file/folder symlink create/delete/rename
directory junction create/delete/rename

It is not updated for these actions:

modified contents of file directly in target folder
edit target of symlink or junction contained in target folder
file's or sub-folder's created/modified date changing
edit basic attributes (hidden/archive/system) of a direct child
NTFS compression/encryption change of a direct child
anything at all happening in a sub-folder - literally anything
changing attributes of the folder itself
changing owner/ACL of the folder itself
owner or ACL of a direct child changing
if the folder is a directory junction, changing the target
adding/deleting alt data streams to a direct child file

来源：https://stackoverflow.com/questions/1025187/rules-for-date-modified-of-folders-in-windows-explorer

标签

windows

datetime

explorer