# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/\<span\sclass\=\"js_value\stab-weather__value_l\"\>\s*+([+-]\d++)\s*+\<span\sclass\=\"tab-weather__value_m\"\>\s*+([.,]\d++)(?:\s*+\<\\/span\>){2}/$1$2/gm;t' <<< "<span class=\"js_value tab-weather__value_l\">
+6<span class=\"tab-weather__value_m\">,2</span></span>
<span class=\"js_value tab-weather__value_l\">
-12<span class=\"tab-weather__value_m\">.45</span></span>
<span class=\"js_value tab-weather__value_l\">
+0<span class=\"tab-weather__value_m\">,1</span></span>"
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