an example luvit/luv spawn a process and connect stdout to stdout or file

spawn_ls_exit_code.lua

local uv = require("luv")

local options = {
  stdio = {
    nil,
    1,
    nil
  }
}

local child, pid = uv.spawn("ls", {"-l"}, options)
function child:onexit(code, signal)
  print("EXIT", "code", code, "signal", signal)
  uv.close(child)
end

repeat
until uv.run('once') == 0

spawn_ls_stdout_to_file.lua

local uv = require "luv"

local fd = uv.fs_open('ls_output.txt', 'w', tonumber('644', 8))

local options = {
  stdio = {
    0,
    fd,
    2
  }
}
local child, pid = uv.spawn("ls", {"-l"}, options)
uv.fs_close(fd)

spawn_ls_stdout_to_stdout.lua

local uv = require "luv"

local options = {
  stdio = {
    nil,
    1,
    nil
  }
}
local child, pid = uv.spawn("ls", {"-l"}, options)

luvit/luv repository is at https://github.com/luvit/luv

See also:

• https://github.com/luvit/luv/blob/master/examples/test-spawn.lua
• https://github.com/luvit/luv/blob/master/examples/test-spawn-stdio.lua