Q:

line breaks based on sequence of characters

I have lines of parameters in a text file, which can be spread over several lines. They are terminated (the actual line break) by a sequence of characters, which can also be spread over several lines or contain spaces like these three (non-exhaustive) examples:
< x >

< x 
  > 

<   x >

I would like to tidy this text file up so that I can actually parse it. The output should be something like this (P1 … P3 are parameters):
P1 P2 P3 < x >
P1 P2 P3 < x >
P1 P2 P3 < x >

Original:
P1 P2 P3 < x   >

P1 P2    P3 < x 

>
P1 P2 

P3 < 
x >

A:

You should do fine with a simple lexical analyzer.
See some previous SO questions:

Recommendations for a good C#/ .NET based lexical analyser
C#/.NET Lexer Generators

