Documentation copy /u

Oct 18, 2008
277
1
Hello --- just to confirm, when files are copied (or moved) with the /u (or /c) switch, the entire 64 bit value of the ntfs (file) timestamp is used? so if the timestamp of a file just differs is in the "sub second" part of the file, that would cause the files to me copied ( or not)?
 
May 20, 2008
9,274
62
Syracuse, NY, USA
If the source and destination are both NTFS, it looks like it uses every one of those 64 bits.
Code:
v:\> echo %@fileage[f2.txt]
131789272146787914

v:\> echo %@fileage[pluggies\f2.txt]
131789272146787913

v:\> copy /u f2.txt pluggies\
V:\f2.txt =>! V:\pluggies\f2.txt
     1 file copied

v:\> echo %@fileage[pluggies\f2.txt]
131789272146787914
Code:
v:\> echo %@fileage[f2.txt]
131789275491168791

v:\> echo %@fileage[pluggies\f2.txt]
131789275491168790

v:\> move /u f2.txt pluggies\
V:\f2.txt ->! V:\pluggies\f2.txt
     1 file moved

v:\> echo %@fileage[pluggies\f2.txt]
131789275491168791
 
May 20, 2008
9,274
62
Syracuse, NY, USA
And
Code:
v:\pluggies> echo %@fileage[f2.txt]
131789278179897159

v:\pluggies> echo %@fileage[v:\f2.txt]
131789278179897160

v:\pluggies> copy /u f2.txt ..\
     0 files copied

v:\pluggies> move /u f2.txt ..\
     0 files moved
 
Oct 18, 2008
277
1
thanks for the info --- this could be problematic if programs are not adding in the nano-seconds
 
May 20, 2008
9,274
62
Syracuse, NY, USA
I first tested with TCC's TOUCH which only uses milliseconds and that's only good to one tick of the system clock (typically about 15.6 milliseconds). Then I wrote my own (in C) which made two FILETIMEs which differed by 1. That behavior is not at all normal. Even if a program uses GetSystemTimeAsFileTime to get a timestamp, that is only updated with every tick of the system clock ... typically every ~15.6 milliseconds. My current "system time adjustment" is 156003 (ten-millionths of a second). If I look at what GetSystemTimeAsFileTime gives (using my plugin _AGENOW), that's exactly the increment I see (~15.6 ms).

Code:
do forever ( echo %_agenow )
<snip>
131789451506789980
131789451506789980
131789451506789980
131789451506945983
131789451506945983
131789451506945983
 
May 20, 2008
9,274
62
Syracuse, NY, USA
My point was that programs can't even come close to using nanoseconds. Typically they get ticks of the system clock (~15.6 milliseconds). Even using HiRes timing (which is system-wide and a bit rude) you can only get that down to 1 ms.
 
Oct 18, 2008
277
1
My point was that programs can't even come close to using nanoseconds. Typically they get ticks of the system clock (~15.6 milliseconds). Even using HiRes timing (which is system-wide and a bit rude) you can only get that down to 1 ms.
again -- thx for the info
 

rps

Jul 6, 2008
388
4
thanks for the info --- this could be problematic if programs are not adding in the nano-seconds
Couldn't using a time range with the copy help?
You can even specify which of the three Windows times to use.