code: function init(opts) {
  	if (!opts) opts = {}
  	if (opts.infoLog != null) infoLog = opts.infoLog
  	if (typeof opts.opsShutdown === 'function') opsShutdown = opts.opsShutdown
  	if (typeof opts.log === 'function') log = opts.log
  	if (opts.appName) appName = opts.appName + ':' + process.pid
  	var signals = opts.signals || {}
  	for (var signal in knownSignals) { // add knownSignals default listeners
  		if (signals[signal] !== false) ensureListener(signal, knownSignals[signal])
  	}
  	for (var signal in signals) { // add additional ignoring listeners
  		if (!knownSignals[signal] || signals[signal] === true) ensureListener(signal, ignoringHandler(signal))
  	}
  	if (opts.appInfo) appInfo = opts.appInfo
  	if (opts.tmpFolder) tmpFolder = opts.tmpFolder
  }
docs: /*
  Configure shutdown
  opts: optional object
  .log optional function log, default console.log
  infoLog: boolean default true: log more than minimum
  .opsShutdown(cb): optional function invoked right before process.exit
  .appName: optional string prepended to log, default 'unknown:pid'
  .signals: optional array of string
  - default signals: uncaught sigint sigusr2 configured unless false
  - other signals: configured if true
  .appInfo: optional object that is written to the filesystem by default sigusr2 handler
  .tmpFolder: optional string: set folder for .appInfo writes, defaults writes don't happen
  
  only act on the options that are present