txt = "This is line one." + newline + "Here is line two." + newline + "Last but not least.";
pat = lineBoundary("start") + wildcardPattern(1,inf) + lineBoundary("start");
パターンを抽出します。
extract(txt,pat)
ans = 2×1 string
"This is line one.↵"
"Here is line two.↵"