Using ST_ATIME to watch for files being read

[Christos TZOTZIOY Georgiou]

On 2 Apr 2004 07:39:38 -0800, rumours say that iamlevis3 at hotmail.com
(Chris) might have written:

Hi Chris,

>I need to monitor a bunch of files to see what is being opened, read,
>and closed, with no modifications being made.  This is being done
>first on Windows machines, and later on Solaris.

<snip>

># from the i.shell.  st_atime date is inside >>><<<
>>>> os.stat("c:\\devtemp\\python\\1.txt")
>(33206, 0L, 2, 1, 0, 0, 3L, >>>1080919329<<<, 1080919329, 1080918583)

># now i open c:\devtemp\python\1.txt, close it, and rerun

How exactly do you open the file?  Through python or through an external
program (eg notepad)?  If only through python, do you read any data?  I
believe you have to read data for the access time to be updated.

>>>> os.stat("c:\\devtemp\\python\\1.txt")
>(33206, 0L, 2, 1, 0, 0, 3L, >>>1080919329<<<, 1080919329, 1080918583)
>
>The Win32 books states that stat.ST_ATIME is "the time the file was
>last accessed or zero if the filesystem doesn't support this
>information".  Obviously I'm missing something, or maybe atime isn't
>the best thing for me to use in this situation.  Hoping someone can
>provide guidance.

Windows has a weird behaviour even with st_mtime... I have a directory
structure in a USB disk, which, taking advantage of NTFS capability for
hard links, I present under two different views for the users of my
network.  To avoid re-reading the contents of all files, I keep a cache
of (relative-filename, size, modification time); by comparing the cache
to the actual directory structure, every time I change a couple of
files, I read only the changed ones to decide where in the linked
structures I will present them.

I have found (through trial and error) that the modification time does
not show up immediately, esp. if the file is modified in the linked
directory structures... I tried even using a sync.exe from sysinternals,
but that doesn't change a lot.  So, after a change, I wait a couple of
minutes and then I run the python script that relinks the files.
Everything works this way.
-- 
TZOTZIOY, I speak England very best,
Ils sont fous ces Redmontains! --Harddix