regex - Extracting text between two keywords or a keyword and \n -

i have set of lines of them follow format

startkeyword text want extract endkeyword\n

i want find these lines , extract information them.

note, text between keywords can contain wide range of characters (latin , non-latin letters, numbers, spaces, special characters) except \n.

endkeyword optional , can omitted.

my attempts revolving around regex

startkeyword (.+)(?:\n| endkeyword)

however capturing group (.+) consumes many characters possible , takes endkeyword not need.

is there way some text want extract solely regular expressions?

you can make (.+) non greedy (which default greedy , eats whatever comes in way) adding ? , add $ instead of \n making more efficient

startkeyword (.+?)(?:$| endkeyword$)

if want \n can use:

startkeyword (.+?)(?:\n| endkeyword\n)

UV code