#!/usr/bin/env lua
-- like plain grep, but first arg is not the needle, but a file containing a list of needles

function lines(fname)
	local lst = {}
	local f = io.open(fname)
	for line in f:lines() do table.insert(lst, line) end
	return lst
end

if select('#', ...) ~= 2 then print("syntax: multigrep needles haystack") return end

local needles  = lines(select(1, ...))
local haystack = lines(select(2, ...))
table.sort(needles)
table.sort(haystack)

local pos = 1
local found = false

for i, n in ipairs(needles) do
	for i, h in ipairs(haystack) do
		local f = h:find(n, 1, true)
		if f then print(h) end
		found = found or f
	end
end

os.exit(found and 0 or 1)