[tex-live] ctan->tl updates caught up

[Zdenek Wagner]

2012/8/3 Philip TAYLOR <P.Taylor at rhul.ac.uk>:
>
>
> T T wrote:
>
>>> 2) Why, if this step can be safely omitted under Windows, can it
>>>          not be safely omitted for all operating systems ?
>>
>>
>> Why change sane defaults on other systems, when issues are only on
>> Windows?
>
>
> I don't think that really answers my question, Tomek :
> if it is not necessary to modify the "last modified" date
> on Windows, why is it necessary to modify it on any other
> operating system ?
>
There is a good reason. People usually routinely make backup. To copy
the whole disk every day (or in some companies several times a day)
would be very expensive, thus the backup is incremental and it is
necessary to know what was changed from the last backup time. The
archive bit is not available in most file systems while the
last-modified time is. As a matter of fact, in Linux it is not
modified by tar but by the file system kernel drivers and the user
cannot change it. The last modified time is changed even if only file
permissions are modified and the file contents remains unchanged, thus
if the file is damaged and restored from a backup copy, it will be
restored with the correct file permissions. AFAIK the archive bit is
also automatically reset if a file is modified.

In a user program it is not easy to find out what features are offered
by the underlying file system. Thus even on Windows TL can be
installed on a file system where the archive bit is unsupported. I do
have Windows (old XP in a virtual machine) and I can connect a network
drive from a Linux computer with the EXT3 file system. Since I
sometimes have to show someone how TeX Live works in Windows, I
install Windows binaries in Linux and use TL in Windows via that
network drive. It is nothing special, Masaryk University in Brno does
the same, they have on Unix installation with binaries for al
platforms shared via network with all computers. Thus in Windows there
may be cases when you can rely on last-modified only, not on the
archive bit.

>
> ** Phil.
> --
> MIL-05991/237/2012-B : Any loss of data or other computer malfunction
> resulting directly or indirectly from the use of Linux will be regarded as a
> self-inflicted injury and treated accordingly.  Users of Mac OS/X will be
> assumed to be insane.  You have been warned ...



-- 
Zdeněk Wagner
http://hroch486.icpf.cas.cz/wagner/
http://icebearsoft.euweb.cz