Usage: sudo.js -u nobody whoami

sudo.js

#!/usr/bin/env node

var args = process.argv.slice(2)
  , arg
  , requestedUid = 0
  , cmd = []
  , cmdArgs
  , tty = process.binding("stdio")
  , path = require("path")
  , usage = path.basename(__filename)
          + " [-u <user>]"
          + " <cmd>"
          + "\nRun <cmd> as <user>"

while (arg = args.shift()) {
  switch (arg) {
    case "--":
      cmdArgs = true
      break
    case "-u": case "--uid": case "--user":
      requestedUid = args.shift()
      break
    case "-h": case "--help": case "-?":
      console.error(usage)
      process.exit(0)
      break
    default:
      cmdArgs = true
      cmd.push(arg)
      break
  }
}
if (!cmd) {
  console.error(usage)
  process.exit(1)
}

var cp = require("child_process")
  , opts = { env : process.env
           , cwd : process.cwd()
           , customFds : [ tty.stdinFD
                         , tty.stdoutFD
                         , tty.stderrFD ]}
var child
if (0 === process.getuid()) {
  process.setuid(requestedUid)
  child = cp.spawn(cmd.shift(), cmd, opts)
} else {
  child = cp.spawn("sudo", process.argv, opts)
}
child.on("exit", function (code) { process.exit(code) })