# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/((<(.|\n)+?>)?[^=])//g;t' <<< "<html style='aklfhnakfn'>This is test content
<head font=\"13\"> dummy head </head>
<p> This is a sample?<a href=\"www.google.com\"> a=b=c=d test release </a> </p>
<p> Dummy a = b = c= d </p>
</html>"
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 SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html