@@ -44,6 +44,7 @@ Logging Options:
     -D, --debug                      Enable debugging output
     -V, --trace                      Trace the raw protocol
     -DV                              Debug and trace
+    --sys_trace                      Trace the system account (default: false)
 
 Authorization Options:
         --user <user>                User required for connections
// Copyright 2012-2019 The NATS Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"flag"
	"fmt"
	"os"

	"github.com/nats-io/nats-server/v2/server"
)

var usageStr = `
Usage: nats-server [options]

Server Options:
    -a, --addr <host>                Bind to host address (default: 0.0.0.0)
    -p, --port <port>                Use port for clients (default: 4222)
    -P, --pid <file>                 File to store PID
    -m, --http_port <port>           Use port for http monitoring
    -ms,--https_port <port>          Use port for https monitoring
    -c, --config <file>              Configuration file
    -sl,--signal <signal>[=<pid>]    Send signal to nats-server process (stop, quit, reopen, reload)
                                     <pid> can be either a PID (e.g. 1) or the path to a PID file (e.g. /var/run/nats-server.pid)
        --client_advertise <string>  Client URL to advertise to other servers
    -t                               Test configuration and exit

Logging Options:
    -l, --log <file>                 File to redirect log output
    -T, --logtime                    Timestamp log entries (default: true)
    -s, --syslog                     Log to syslog or windows event log
    -r, --remote_syslog <addr>       Syslog server addr (udp://localhost:514)
    -D, --debug                      Enable debugging output
    -V, --trace                      Trace the raw protocol
    -DV                              Debug and trace

Authorization Options:
        --user <user>                User required for connections
        --pass <password>            Password required for connections
        --auth <token>               Authorization token required for connections

TLS Options:
        --tls                        Enable TLS, do not verify clients (default: false)
        --tlscert <file>             Server certificate file
        --tlskey <file>              Private key for server certificate
        --tlsverify                  Enable TLS, verify client certificates
        --tlscacert <file>           Client certificate CA for verification

Cluster Options:
        --routes <rurl-1, rurl-2>    Routes to solicit and connect
        --cluster <cluster-url>      Cluster URL for solicited routes
        --no_advertise <bool>        Advertise known cluster IPs to clients
        --cluster_advertise <string> Cluster URL to advertise to other servers
        --connect_retries <number>   For implicit routes, number of connect retries


Common Options:
    -h, --help                       Show this message
    -v, --version                    Show version
        --help_tls                   TLS help
`

// usage will print out the flag options for the server.
func usage() {
	fmt.Printf("%s\n", usageStr)
	os.Exit(0)
}

func main() {
	exe := "nats-server"

	// Create a FlagSet and sets the usage
	fs := flag.NewFlagSet(exe, flag.ExitOnError)
	fs.Usage = usage

	// Configure the options from the flags/config file
	opts, err := server.ConfigureOptions(fs, os.Args[1:],
		server.PrintServerAndExit,
		fs.Usage,
		server.PrintTLSHelpAndDie)
	if err != nil {
		server.PrintAndDie(fmt.Sprintf("%s: %s", exe, err))
	} else if opts.CheckConfig {
		fmt.Fprintf(os.Stderr, "%s: configuration file %s is valid\n", exe, opts.ConfigFile)
		os.Exit(0)
	}

	// Create the server with appropriate options.
	s, err := server.NewServer(opts)
	if err != nil {
		server.PrintAndDie(fmt.Sprintf("%s: %s", exe, err))
	}

	// Configure the logger based on the flags
	s.ConfigureLogger()

	// Start things up. Block here until done.
	if err := server.Run(s); err != nil {
		server.PrintAndDie(err.Error())
	}
	s.WaitForShutdown()
}

I like it from some tools that they use `-vv` and `-vvv` to define "very verbose" and extra verbose levels on the command line, (examples I can think of are memcached and curl), maybe could be a good fit for the nats-server too? Could be in this case that `-VV` means very verbose, activating tracing of system events for example