io.lua

local levee = require("levee")
local _ = levee._

local h = levee.Hub()

_.fcntl_nonblock(0); h.stdin = h.io:r(0)
_.fcntl_nonblock(1); h.stdout = h.io:w(1)

local stream = h.stdin:stream()

local count= 0

while true do
  local err, line = stream:line()
  if err then break end
  h.stdout:send(line, "\n")
  count = count + 1
end

h.stdout:send(("count: %s\n"):format(count))
h.stdout.empty:recv()

run.sh

imgix:tmp andy$ for i in $(seq 1 3) ; do echo $i; sleep 1; done | levee run io.lua
1
2
3
count: 3