What's the best way to search for a string in a file?

Question

The title speaks for itself really. I only want to know if it exists, not where it is. Is there a one liner to achieve this?

Answer 1

This reads the file only to the first appearance of 'string' and processes it line by line - not reading the whole file at once.

def file_contains_regexp?(filename,regexp)
  File.foreach(filename) do |line|
    return true if line =~ regexp
  end
  return false
end