re = /(?:\h*<!-- ARTICOL START -->\R|\G)\K(?:(<p class=.*?<\/p>\R?)|(?:(?!<p class=.*?<\/p>)[\s\S])+)(?=[\s\S]+<!-- ARTICOL FINAL -->)/m
str = ' <!-- ARTICOL START -->
<div align="justify">
<table width="682" border="0">
<tr>
<td><h1 class="den_articol" itemprop="sfe">My text here</h1></td>
</tr>
<tr>
<td class="text_dreapta">On Ianuarie 14, 2014, in <a href="https://neculaifantanaru.com/en/qualities-of-a-leader.html" title="See al articles from Qualities of a leader" class="external" rel="category tag">Qualities of a leader</a>, by Author</td>
</tr>
</table>
<h2 class="text_obisnuit2"><img src="index_files/sfa.jpg" width="718" height="605" id="sfs" usemap="#m_dgrnt" alt="hip" /><map name="tfAbonament" id="m_34">
<area shape="rect" coords="259,545,457,582" href="#plata" alt="" />
</map></h2>
<p class="den_articol">Why this text text?</p>
<p class="text_obisnuit">test text text</p>
<p class="text_obisnuit">test text text</p>
<p class="text_obisnuit2">test text text</p>
</div>
<p align="justify" class="text_obisnuit style3"> </p>
<!-- ARTICOL FINAL -->'
subst = '$1'
result = str.gsub(re, subst)
# Print the result of the substitution
puts result
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Ruby, please visit: http://ruby-doc.org/core-2.2.0/Regexp.html