File and Directory Times

Coordinated universal time (UTC) is the standard international time used internally by the system. UTC is loosely defined as the current date and time of day in Greenwich, England. This time is called also Greenwich mean time (GMT).

Local time is the date and time of day for your time zone. The current time-zone settings control how the system converts between UTC and local time.

A file time represents the specific date and time at which a specified file was created, last accessed, or last written to. The system records file times whenever applications create, access, and write to files. The system records the times using a 64-bit value specifying the number of 100-nanosecond intervals that have elapsed since 12:00 A.M. January 1, 1601 (UTC). Writing to a file changes the last write time; writing to or reading from the file (including running an executable file) changes the last access time.

Note Not all file systems can record creation and last access time and not all file systems record them in the same manner. For example, on Windows NT FAT, create time has a resolution of 10 milliseconds, write time has a resolution of 2 seconds, and access time has a resolution of 1 day (really, the access date). On NTFS, access time has a resolution of 1 hour. Furthermore, FAT records times on disk in local time, while NTFS records times on disk in UTC, so it is not affected by changes in time zone or daylight saving time.

See Also

File Systems