# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/<label .*?>(.*?)<\\/label>/$1/g;t' <<< "<label class=\"s-nav right\" for=\"s-22\">simply</label>
<label class=\"s-nav left\" for=\"s-21\">dummy</label>
<label class=\"s-nav right\" for=\"s-23\">text</label>
<label class=\"s-nav left\" for=\"s-22\">of the printing</label>
<label class=\"s-nav right\" for=\"s-24\">and typesetting</label>
<label class=\"s-nav left\" for=\"s-23\">industry</label>
<label class=\"s-nav right\" for=\"s-25\">Lorem Ipsum</label>
<label class=\"s-nav left\" for=\"s-24\">Ipsum</label>"
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