Question

I have the following code snippet from a HTML file:

<div id="rwImages_hidden" style="display:none;">
    <img src="http://example.com/images/I/520z3AjKzHL._SL500_AA300_.jpg" style="display:none;"/>
    <img src="http://example.com/images/I/519z3AjKzHL._SL75_AA30_.jpg" style="display:none;"/>
    <img src="http://example.com/images/I/31F-sI61AyL._SL75_AA30_.jpg" style="display:none;"/>
    <img src="http://example.com/images/I/71k-DIrs-8L._AA30_.jpg" style="display:none;"/>
    <img src="http://example.com/images/I/61CCOS0NGyL._AA30_.jpg" style="display:none;"/>
</div>

I want to extract the code

520z3AjKzHL
519z3AjKzHL
31F-sI61AyL
71k-DIrs-8L
61CCOS0NGyL

from the HTML.

Please note that: <img src="" style="display:none;"/> must be used because there are other similar urls in HTML file but I only what the ones between <img src="" style="display:none;"/>.

My Code is:

cat HTML | grep -Po '(?<img src="http://example.com/images/I/).*?(?=.jpg" style="display:none;"/>)'

Something seems to be wrong.

Answer 1

You can solve it by using positive look ahead / look behind:

cat HTML | grep -Po "(?<=<img src=\"http://example.com/images/I/).*?(?=\._.*.jpg\" style=\"display:none;\"/>)"

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Demonstration:

• ideone.com link

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Regexp breakdown:

• .*? match all characters reluctantly
• (?<=<img src=...ges/I/) preceeded by <img .../I/
• (?=\._...ne;\"/>) succeeded by ._...ne;\"/>