Ruby find string in file and print result

Question

It\'s been a very long time since I\'ve used ruby for things like this but, I forget how to open a file, look for a string, and print what ruby finds. Here is what I have:

Answer 1

File.open 'file.txt' do |file|
  file.find { |line| line =~ /regexp/ }
end

That will return the first line that matches the regular expression. If you want all matching lines, change find to find_all.

It's also more efficient. It iterates over the lines one at a time, without loading the entire file into memory.

Also, the grep method can be used:

File.foreach('file.txt').grep /regexp/