Hi, Thanks for your reply!
Say, I have a index.html which is not changed, but some of the pages
linked from this page might be changed. When I use -N option to retrieve
index.html recursively, wget will quit after find out that index.html is
not changed, without following the url in index.html, and thus missed the
fact that some other pages being linked by index.html might have been
changed.
Am I right? Or I am wrong? Thanks.
> Date: Sat, 4 Aug 2001 17:15:45 +0100
> From: Ian Abbott <[EMAIL PROTECTED]>
> To: [EMAIL PROTECTED], "Bao, Jiangcheng" <[EMAIL PROTECTED]>
> Subject: Re: wget timestamping (-N) bug/feature?
>
> On 4 Aug 2001, at 3:25, Bao, Jiangcheng wrote:
>
> > Suppose I have page a.html, which has a link to b.html. If a is not
> > changed, and b is changed. When I process a, I have no way to check a so
> > that I can process b too, without downloading a. -N will cause a not to be
> > downloaded, but not processed either, so change of b will be ignored. If I
> > will -nc, then a will be processed, and b too, but b's change will still
> > be ignored. If a new page c is linked into b now, then c won't get
> > noticed.
> >
> > Is this a feature or it's a bug? Thanks.
>
> What version of wget are you using, since I've just tried your
> scenario in wget 1.7 and it worked correctly. I used the -N and -r
> options, but you could just use the -m option instead which combines
> these two options (timestamp checks and recursion).
>
> If you use the -nc option then no new versions of the pages that are
> already stored locally will be downloaded so you won't see the
> changed versions and (if using recursion) wget will process the old,
> existing versions. In this case, wget doesn't need to request any
> thing at all from the web server for files it already has.
>
> If you use the -N option (or -m) then if the local file exists, wget
> will at first ask the web server for just the HTTP headers, rather
> than the whole document. The "Last-Modified" and "Content-Length"
> HTTP response headers will be compared with the last-modified time
> and length of the local file (if it exists) and if the local file
> does not exists, the lengths are different or the local file is older
> than than the new content, another request will be sent to the web
> server to retrieve the whole document.
>
> So when you say -N will cause files that are not downloaded to not be
> processed, you are incorrect, at least as far as wget 1.7 is
> concerned.
>
Jiangcheng Bao
