Simple TCP Echo Server in Lua

echo.lua

-- sudo luarocks install luasocket
-- sudo apt install lua-socket
local socket=require("socket")

local server=assert(socket.bind("localhost",9999))
server:settimeout(0) -- for server:accept()

local ip,port=server:getsockname()
print("ncat".." "..ip.." "..port)

local clients={}
while true do -- don't exit

-- new client
local client_new,err=server:accept()
if client_new then
  client_new:settimeout(0) -- for client:receive()
  table.insert(clients,client_new)
end

-- clients
for i,client in ipairs(clients) do
  --print(i.." receive...") -- debug info
  local msg=client:receive()
  if msg then
    --print("received: "..msg) -- debug info
    client:send(msg.."\n") -- send back
  end
end

end -- end while
server:close()