There's no on-disc Last Change timestamp the Last Access timestamp has a granularity of 1 day and the Last Write and Creation timestamps have a granularity of 2 seconds. Seeing why the 1st few times takes longer. Windows NT's FAT filesystem driver, and the FAT filesystem driver in DOS+Windows 95/98/ME, used theretofore spare fields in directory entries for storing more timestamps. To convert a single files date/time to EXIF values requires Shift-J, Alt-F, Enter. The FAT filesystem format, for example, originally only had one timestamp per file: its Last Write timestamp. That's the API that filesystem drivers have to implement.īut not all filesystems actually have them defined in the on-disc data structures, or have them defined to the same granularity as the Windows NT kernel does. After you have selected the files, click the blue upload button. To pick and choose files, hold down the Command key (mac) or Control key (PC) and then click-select multiple files. It is changes to a file's metadata, in the I-node/MFT Record, that influence the Last Changed timestamp.Įvery filesystem in Windows NT has to provide these four timestamps to the kernel. To select multiple files in sequence, use the shift key. It doesn't change the Last Write timestamp because that is only influenced by changes to a file's data. in windows command line i can use the following to change the timestamp of a file to the current datetime: copy /b filename. So changing a file's attrtibutes - read-only, hidden, system, archive, index, offline, and so forth - with SetFileAttributes will update its Last Changed timestamp. Windows NT sets the timestamp even if the thing that is changed is changed from Win32, since (of course) both subsystems are layered over the native API when it comes to files. In POSIX, the I-node Changed timestamp reflects the time that something in the I-node - permissions, owner, group, and so forth - is changed. Windows NT, and NTFS, in order to support both Win32 and POSIX thus give files four timestamps: Creation, Last Write/Modified, Last Access, and Last Changed. POSIX has Last Modified, Last Access, and I-node Changed timestamps. In Win32, files have Creation, Last Write, and Last Access timestamps. You can get the last modification time of a file with stat, and the current date with date. Two of those timestamps are common to Win32 and POSIX. In both Win32 and POSIX, files have three timestamps. Windows NT has, since inception, supported both a Win32 subsystem and a POSIX subsystem.
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