Installing TigerVNC in Ubuntu 24.04

Ubuntu 24.04 supports RPD protocol but it behaves in a way that is not fit for my needs. The Desktop Sharing mode needs to have a user logged in or set to automatically login on reboot. Anyone will have access to your desktop if they are physically present. The Remote Login would have been the best option but when the connection is lost, all applications running on that session are gone. So you can't reconnect to that same session.

So, we are back to the tried and tested VNC protocol. To get TigerVNC working on Ubuntu 24.04 is a little tricky due to Wayland becoming the default in 24.04. To workaround Wayland, we need to install XFCE, like so:

$ sudo apt install --no-install-recommends xubuntu-desktop

This installs base XFCE4 with very applications specific to XFCE.

Install xfce4-terminal for convenience. GNOME-Terminal is pretty heavy and uxterm/xterm are not to my liking.

$ sudo apt install xfce4-terminal

Now install TigerVNC

$ sudo apt install tigervnc-standalone-server

Then set the password that will be used to connect to the VNC server by running it like below:

$ vncpasswd

Now we have to define the mapping between a VNC session and user for that session. To do this open /etc/tigervnc/vncserver.users, like:

$ sudo vim /etc/tigervnc/vncserver.users

Below is an example that shows user u1 is mapped to VNC server session 2:

# TigerVNC User assignment
#
# This file assigns users to specific VNC display numbers.
# The syntax is <display>=<username>. E.g.:
#
# :2=andrew
# :3=lisa
:2=u1

Now run VNC server, like:

$ vncserver -geometry=1360x768 -xstartup /usr/bin/startxfce4 :2 -localhost no

Using RealVNC client on Windows, you can calculate geometry of the server like this to get maximum client area: The same script can be used to calculate client dimensions for remote desktop client.

Should you need to close/kill the session, do:

$ vncserver -kill :2

There is a big caveat that I haven't figured out, yet. No user should be logged in to the console/physical session. Otherwise, everything goes crazy.
References:
https://medium.com/oracledevs/your-next-developer-desktop-with-ubuntu-24-04-and-tigervnc-on-oci-d0356ffa0cf9

Error opening directory '/media/sf_C_DRIVE': Permission denied

I tried to share a folder from Windows 10 host to Kali 2020.1 Linux guest using VirtualBox but I am getting the following error message:

Error opening directory '/media/sf_C_DRIVE': Permission denied

To fix, do:

$: sudo adduser $USER vboxsf

Then log-off then log back in. If this does not work, reboot the VM

Getting similar issue using Fedora 33(tested up to Fedora 40) on VirtualBox 7.0.12, below is the error message

This location could not be displayed You do not have the permissions necessary to view the contents of "sf_D_DRIVE"

To fix do the following and reboot the VM.

$: sudo usermod -a -G vboxsf $USER

Refs:
https://stackoverflow.com/questions/26740113/virtualbox-shared-folder-permissions

Install Winget on Windows 2022 or Windows 10 LSTC

Install Winget on Windows 2022 or Windows 10 LTSC

Install Pre-reqs

Install Microsoft.UI.Xaml/2.8.6

Navigate to https://www.nuget.org/packages/Microsoft.UI.Xaml/2.8.6, on the left side look for Download Package button to download microsoft.ui.xaml.2.8.6.nupkg.

Using 7-zip, extract microsoft.ui.xaml.2.8.6.nupkg\tools\AppX\x64\Release\Microsoft.UI.Xaml.2.8.appx

Install

PS C:\>Add-AppxPackage .\Microsoft.UI.Xaml.2.8.appx

Install Microsoft.VCLibs.140.00.UWPDesktop

Download https://aka.ms/Microsoft.VCLibs.x64.14.00.Desktop.appx

Install

PS C:\>Add-AppxPackage .\Microsoft.VCLibs.x64.14.00.Desktop.appx

Install Winget

Download Microsoft.DesktopAppInstaller_8wekyb3d8bbwe.msixbundle or any recent versions (tested using 1.8.1911) from Github

Download license file 76fba573f02545629706ab99170237bc_License1.xml (should be one of the artifacts) from Github, the same URL from above.

Install (on elevated cmd/shell)

PS C:\>cd ~/Downloads
PS C:\Users\u1\Downloads> Add-AppxProvisionedPackage -Online -PackagePath .\Microsoft.DesktopAppInstaller_8wekyb3d8bbwe.msixbundle -LicensePath .\76fba573f02545629706ab99170237bc_License1.xml -Verbose

If you are in a hurry, you can grab the script below and run it on a PowerShell console
And if you trust me ;), run below:

iex (Invoke-RestMethod -Uri "https://gist.githubusercontent.com/technoscavenger/37f06e23daa833d0c7bee1d378ff332e/raw/122d300c8a6bb711dcd70652551599818dfdb09e/InstallWinget.ps1")

Refs: https://8thstring.blogspot.com/2023/04/install-winget-on-windows-2022.html

QNX: Running a function at specific interval using timer interrupt

#include <iostream>
#include <csignal>
#include <ctime>
#include <cerrno>
#include <cstring>
#include <unistd.h>
#include <sys/time.h>
#include <time.h>
#include <stdio.h>

void timer_handler(int signo) { 
    struct timeval tv;
    gettimeofday(&tv, NULL);
    char buf[100];
    struct tm* nowtm;
    nowtm = localtime(&tv.tv_sec);
    strftime(buf, sizeof(buf), "%Y-%m-%d %H:%M:%S", nowtm);
    printf("Timer expired at %s.%03ld\n", buf, tv.tv_usec / 1000);
}

int main() {
    timer_t timerid;
    struct sigevent sev;
    struct itimerspec its;
    struct sigaction sa;

    // Install the timer handler
    sa.sa_flags = 0;
    sa.sa_handler = timer_handler;
    sigemptyset(&sa.sa_mask);
    if (sigaction(SIGRTMIN, &sa, NULL) == -1) {
        std::cerr << "sigaction: " << errno << std::endl;
        return -1;
    }

    // Create the timer
    sev.sigev_notify = SIGEV_SIGNAL;
    sev.sigev_signo = SIGRTMIN;
    if (timer_create(CLOCK_REALTIME, &sev, &timerid) == -1) {
        std::cerr << "timer_create: " << errno << std::endl;
        return -1;
    }

    // Set the timer to expire every second
    its.it_value.tv_sec = 1;
    its.it_value.tv_nsec = 0;
    its.it_interval.tv_sec = 1;
    its.it_interval.tv_nsec = 0;
    if (timer_settime(timerid, 0, &its, NULL) == -1) {
        std::cerr << "timer_settime: " << errno << std::endl;
        return -1;
    }

    // Main loop
    while (true) {
        pause(); // Wait for signals
    }

    return 0;
}

CPP Quick Guide

Basics
Hello world
User input
While loop
If statement
For loop
Switch statement
Read file using ifstream
Write to a file using ofstream

Containers
Basic usage of std::list
Basic usage of std::map
Basic usage of std::vector
Data type conversion

Windows API with Exmaples
DeviceIoControl
FindFirstVolumeW
GetDiskFreeSpaceExW
GetLogicalDrives
GetLogicalDriveStrings

C++/WinRT
C++/WinRT Hello World

QNX
Using timer interrupt

Qt Cross-platform
Installing Qt Creator 9.0.1 on Windows 10
Qt console hello world
Qt Widget hello world
Qt Widget hello world code only


Keywords: C++, Qt, Programming, Tutorial