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.
{
    rpc_notify_block_change_connection = uiInterface.NotifyBlockTip_connect(std::bind(RPCNotifyBlockChange, std::placeholders::_2));
}
static void OnRPCStopped()
{
    rpc_notify_block_change_connection.disconnect();
    RPCNotifyBlockChange(nullptr);
    g_best_block_cv.notify_all();
    LogPrint(BCLog::RPC, "RPC stopped.\n");
}
void SetupServerArgs(ArgsManager& argsman)
{
    SetupHelpOptions(argsman);
    argsman.AddArg("-help-debug", "Print help message with debugging options and exit", ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST); 
    init::AddLoggingArgs(argsman);
    const auto defaultBaseParams = CreateBaseChainParams(CBaseChainParams::MAIN);
    const auto testnetBaseParams = CreateBaseChainParams(CBaseChainParams::TESTNET);
    const auto signetBaseParams = CreateBaseChainParams(CBaseChainParams::SIGNET);
    const auto regtestBaseParams = CreateBaseChainParams(CBaseChainParams::REGTEST);
    const auto defaultChainParams = CreateChainParams(argsman, CBaseChainParams::MAIN);
    const auto testnetChainParams = CreateChainParams(argsman, CBaseChainParams::TESTNET);
    const auto signetChainParams = CreateChainParams(argsman, CBaseChainParams::SIGNET);
    const auto regtestChainParams = CreateChainParams(argsman, CBaseChainParams::REGTEST);
    
    std::vector<std::string> hidden_args = {
        "-dbcrashratio", "-forcecompactdb",
        
        "-choosedatadir", "-lang=<lang>", "-min", "-resetguisettings", "-splash", "-uiplatform"};
    argsman.AddArg("-version", "Print version and exit", ArgsManager::ALLOW_ANY, OptionsCategory::OPTIONS);
#if HAVE_SYSTEM