Question

Is there anyway to check if a value exist in a file without ALWAYS going through entire file ?

Currently I used:

if open('file.txt').grep(/value/).length > 0
  puts "match"
else 
  puts "no match"
end

But it’s not efficient as I only want to know whether it exists or not. Really appreciate a solution with grep / others similar one-liner.

Please note the “ALWAYS” before down-vote my question

Answer 1

If you want line-by-line comparison using a one-liner:

matches = open('file.txt') { |f| f.lines.find { |line| line.include?("value") } }
puts matches ? "yes" : "naaw"