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The image is generated once every n minutes, and I want to get each of these to my local directory. I had no success in getting the png-image using the command:

wget -r -l1 --no-parent -A.png http://url.com/home/images/

since it is blocked by the site, and I cannot use

wget http://url.com/home/images/filename.png

since the name of the images changes from update to update.

The image is however linked in http://url.com/home/index.html and I could get the file name from there. What is a robust way to do this? I know the pattern to search for: it is the only image that is called from the directory /home/images/.

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    I am successful with your first cmd. Why weren't you? What is missing, what is wrong with it? – polym Jun 19 '14 at 17:14
  • @polym True, there is nothing wrong with the command, it is just that the website does not allow me to get the images that way. Post edited. – Figaro Jun 19 '14 at 17:31
  • Can you print the response? – polym Jun 19 '14 at 17:33
  • There is no error, but wget only finds *.html files that are telling me that the page is missing. However, the png-file can be accessed directly through the browser. – Figaro Jun 19 '14 at 17:39
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    Try my suggestion below. If it still doesn't work, maybe the server is detecting wget requests because of the request header. In this case, you should emulate a browser header. – polym Jun 19 '14 at 17:45
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Two strategies:

  • index.html grep strategy

It only works, as long there is only one png reference in index.html:

#!/bin/bash
wget http://url.com/home/images/index.html
LINK=$(cat index.html | grep -zPo 'href=.*.png"')
LINK=${LINK#href=\"}; LINK=${LINK%\"}
wget --no-parent "http://url.com/home/images/$LINK"
rm index.html
  • Browser emulation by modifying request headers

Examples how to do that are here, here and here.

  • Must try the emulation, too. Thank you. I did try your script, but I am a bit slow on the syntax, when the png is embedded as "<img src="images/img123456.png" width=600 height=600>", how do I extract its path? It is also not the only png. It is however the only image with that path (for now). – Figaro Jun 19 '14 at 17:59
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    If its src, then change all href to src and wget from http://url.com/home/$LINK on line 5 instead of http://url.com/home/images/$LINK. I used simple string manipulation, first i remove the href=" part, second the last ". – polym Jun 19 '14 at 18:44
  • Got it working. Added a | head -1 to the grep so I only got the first (=correct) png. Not the most robust solution, but it is working. – Figaro Jun 19 '14 at 19:30
  • One more thing. How do I get this to work with cron? */5 * * * * /home/user/wget_testbed.sh does not generate any results. – Figaro Jun 19 '14 at 20:26
  • Got it working, had to specify the correct destination folder to wget – Figaro Jun 20 '14 at 16:33

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