On my Linux Mint 19.1:
```bash
$ umask
0022
```

After the first run of `bitcoin-qt -sysperm=false` the `0700` permissions are expected for both the datadir (`~/.bitcoin`) and the walletdir (`~/.bitcoin/wallets`).

Actually, the directories are created with such access permissions:
```bash
$ stat ~/.bitcoin | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
$ stat ~/.bitcoin/wallets | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
```

Refs:
- #4286
- #13371
- #13389

NOTE: reading through the initial PR #4286 makes me think it was controversial. Is it a better and simpler way to just get rid of `-sysperm` option? I believe a user who needs this option can easily run `chown` command.
node.scheduler->scheduleEvery([]{
        RandAddPeriodic();
    }, std::chrono::minutes{1});
    GetMainSignals().RegisterBackgroundSignalScheduler(*node.scheduler);
    
    
    
    
    g_wallet_init_interface.Construct(node);
    uiInterface.InitWallet();
    * Register RPC commands regardless of -server setting so they will be
     * available in the GUI RPC console even if external calls are disabled.
     *
    RegisterAllCoreRPCCommands(tableRPC);
    for (const auto& client : node.chain_clients) {
        client->registerRpcs();
    }
#if ENABLE_ZMQ
    RegisterZMQRPCCommands(tableRPC);
#endif
    * Start the RPC server already.  It will be started in "warmup" mode
     * and not really process calls already (but it will signify connections
     * that the server is there and will be ready later).  Warmup mode will
     * be disabled when initialisation is finished.
     *
    if (args.GetBoolArg("-server", false)) {
        uiInterface.InitMessage_connect(SetRPCWarmupStatus);
        if (!AppInitServers(node))
            return InitError(_("Unable to start HTTP server. See debug log for details."));
    }