OnServerCommand

using UnityEngine;
using System.Linq;
using System;
using System.Collections.Generic;
using Newtonsoft.Json;
using Oxide.Core;

namespace Oxide.Plugins
{
    [Info("Command Blocker", "RustPluginGenerator", "1.0.0")]
    [Description("Blocks configured console commands unless the player has a bypass permission")]
    public class CommandBlocker : RustPlugin
    {
        private const string PermBypass = "commandblocker.bypass";

        private PluginConfig config;
        private HashSet<string> blocked;

        private class PluginConfig
        {
            [JsonProperty("Blocked commands")]
            public List<string> BlockedCommands = new List<string>
            {
                "kill",
                "respawn",
                "global.kill",
                "global.respawn"
            };
        }

        protected override void LoadDefaultConfig() => config = new PluginConfig();

        protected override void LoadConfig()
        {
            base.LoadConfig();
            try
            {
                config = Config.ReadObject<PluginConfig>();
                if (config == null) throw new Exception();
            }
            catch
            {
                PrintWarning("Configuration file is invalid, using defaults");
                LoadDefaultConfig();
            }
            SaveConfig();
        }

        protected override void SaveConfig() => Config.WriteObject(config);

        protected override void LoadDefaultMessages()
        {
            lang.RegisterMessages(new Dictionary<string, string>
            {
                ["Blocked"] = "The command '{0}' is not allowed on this server."
            }, this);
        }

        private string Msg(string key, string userId = null, params object[] args) =>
            string.Format(lang.GetMessage(key, this, userId), args);

        private void Init()
        {
            permission.RegisterPermission(PermBypass, this);
        }

        private void OnServerInitialized()
        {
            blocked = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            foreach (string command in config.BlockedCommands)
            {
                if (!string.IsNullOrEmpty(command))
                    blocked.Add(command.Trim());
            }
        }

        private object OnServerCommand(ConsoleSystem.Arg arg)
        {
            if (arg == null || arg.cmd == null || blocked == null || blocked.Count == 0)
                return null;

            string command = arg.cmd.FullName;
            if (string.IsNullOrEmpty(command) || !blocked.Contains(command))
                return null;

            BasePlayer player = arg.Player();
            if (player == null)
                return null;

            if (permission.UserHasPermission(player.UserIDString, PermBypass))
                return null;

            player.ChatMessage(Msg("Blocked", player.UserIDString, command));
            return false;
        }
    }
}