[Sderby] shell script for retrieving an image file from a remote http server

[Ashley Heath]

On Sat, 3 Jul 2004 00:12:45 +0100
"Paul Grosse" <paul-grosse at ntlworld.com> wrote:

> Folks,
> 
> Does anybody know of a way (using commands that are likely to be found on
> most people's machines) of retrieving an image file from a remote http host?
> The commands would have to be representable in the form of a bash script
> (suitable for running as a cron tab) and I would prefer not to have to have
> people loading programs onto their machines in order to achieve this.
> 
> One thing that sprung to mind was the use of telnet (having the telnet
> command in the shell script) with commands sent to it from its .telnetrc
> file, redirecting the output to a file which could then have the first bits
> of code removed as they are not part of the image.
> 
> Doing this manually, it is something along the lines of...
> +++++++++++++++++++++++++++
> ==In BASH...
> telnet www.xxx.yyy.zzz 80 >[some_directory]/image.png
> 
> ==In Telnet...
> GET /image.png HTTP/1.0[return]
> Host:www.domain.com[return]
> [return]
> 
> ==In [some_directory], have a program that...
> opens the file, finds the content-length data in the header returned by the
> server.
> 
> Then, (possibly another program or line(s) of script) starts from the end
> and counts that number of bytes towards the beginning then trunkates the
> file, leaving just the image in the file (ie, chops the first bit off,
> leaving the rest).
> 
> ==Then, in [some directory] rename the file with the date and time (say, in
> the form of 20040703000335.jpg)
> +++++++++++++++++++++++++++
> and that is all.
> 
> Is there a bit of perl that is something along the lines of lwp-retrieve ...
> that will do the first part of this?
> 
> I think that using telnet is a bit long winded although I don't want to have
> people loading libraries if they have a nice tight system and don't want
> loads of other stuff there that might just compromise their security.
> 
> The idea is that people with web counters can retrieve the image for a
> certain time of the week, every week without having to do it manually - the
> only manual part is inspecting the images to collect the counter values.
> 
> Any ideas anyone???
> 

It would be far easier to use wget (non interactive network downloader), should be standard on all Linux distros
eg wget www.xxx.yyy.zzz/[some_directory]/image.png

Cheers
Ash