# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/<secondary_references>(\[id=(\d+)\]([-, ]{0,2}))*<\/secondary_references>/%/gu;t' <<< "<secondary_references>[id=1],[id=2]</secondary_references>
<secondary_references>[id=1]</secondary_references>
<secondary_references>[id=1]-[id=2]</secondary_references>
<secondary_references>[id=1][id=2]</secondary_references>"
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