# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/\b((?:LON|LAT)\d\t)(\s-?\d+(?:\.\d+)?)\b/$1=$2/gm;t' <<< "LON1 129.97579956
LAT1 -26.33283424
LON2 130.10830688
LAT2 -26.33283424"
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