in glog.go [398:411]
func init() {
flag.BoolVar(&logging.toStderr, "logtostderr", false, "log to standard error instead of files")
flag.BoolVar(&logging.alsoToStderr, "alsologtostderr", false, "log to standard error as well as files")
flag.Var(&logging.verbosity, "v", "log level for V logs")
flag.Var(&logging.stderrThreshold, "stderrthreshold", "logs at or above this threshold go to stderr")
flag.Var(&logging.vmodule, "vmodule", "comma-separated list of pattern=N settings for file-filtered logging")
flag.Var(&logging.traceLocation, "log_backtrace_at", "when logging hits line file:N, emit a stack trace")
// Default stderrThreshold is ERROR.
logging.stderrThreshold = errorLog
logging.setVState(0, nil, false)
go logging.flushDaemon()
}