# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^(1|2)\d{3}\-(0[1-9]|1[0-2])\-((0[1-9])|((1|2)\d)|3(0|1))(T|\s)((0|1)\d|2[0-3]):([0-5]\d):([0-5]\d)((\+0\d|\+1[0-4]|-0\d|-1[0-2])([0-5]d)?)?|(\d{10-13})//g;t' <<< "2018-05-25 23:59:59"
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