Re: [tlug] Web Page Caching: Timestamps, HTTP+HTML,touch (Re: Website Update Prompt -II)

[bruno raoult <bruno@example.com>]

Jim wrote:
> Also, learn the "touch" command. If you are messing around with 
> file timestamps, how to you restore an old version of a file 
> with the old timestamp? 
> 
>    cp -p
>    mv
>    tar (backup and restore)
> 
> The "make" command relies on file timestamps. 

There could be also (even unlikely) a timezone/time issue, if wrongly
set for instance. This does not give days difference, normally, but
easily hours. For instance, the www user (apache or www, depending on
distribs) could have a different timezone from your own user. This is
easy to find with your "touch" (user) and "wget" (apache) commands.

Yes, I know, Linux (and all Unixes) know this well, for local files.
This could happen anyway for file servers and different clients. For
instance, if you "vi" a file on a file server, the time stamp would be
set by the server. But if you "touch" it, the time is given by the
client. That is why there could be some inconsistencies.

Your remark about "make" just remembered me that story: An NFS server,
with 2 different clients, one of them (clients) with wrong time
settings. The "make" command simply did not work on client #1 if you
"touched" a file with client #2 (time set on the file was still in the
past for client #1).

Takes only a second to check, anyway.

br.

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