# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/<input name="__RequestVerificationToken" type="hidden" value="([A-Za-z0-9+=\\/\-\_]+)">//;t' <<< "<input name=\"__RequestVerificationToken\" type=\"hidden\" value=\"fdsafs\">"
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