# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/\{\{(\d+)(,(\d+))?\}\}/<input name="var$1" value="$3" \/>/gmi;t' <<< "This is my first example string. {{1}} This is what it looks like.
This is my second example string. {{1,2}}. This is what it looks like.
This is my third example string. {{1,3}} and {{2}}. This is what it looks like."
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