match regular expression before first \n

[st12iker]

Im looking for a regex expression that would enable me to match a pattern only before the first \n of a line. So for example if I had text

if $\ = $$ and had text
123 DFG\n (1st line)
$$
345\n
3678 DSGDFG\n
678TY&^*\n
(all 2nd line because of $\ = $$)
$$
789DHYUTN\n
345345 SDFGDFG \n
(3rd line)

So I would need a search that would search only the text containing "345", " 123 DFG", and "786 ... " since they are all before the first \n of their respective lines. This is only an example to illustrate what I am having trouble with.

[miller]

since they are all before the first \n of their respective lines

Striker,

This statement makes no sense. The \n is the return character so that denotes when a new line is. What do you mean respective lines?

I believe that this probably is a continuation of your previous thread:
change $/

If this is the case, please limit your discussion to that single thread instead of starting new questions. It helps to know the entire context in which a question is asked, as often a solution to the problem is best presented as an entirely different approach instead of the method that you are current attempting to get to work.

- Miller