OpenGuru Weblog

Run lz4 compression in parallel using GNU parallel

2022-09-07T13:37:00.003+10:00

I like compressing my SQLite DB as separate lz4 files. I use the below commands to compress them in parallel using the lz4 utility.

parallel lz4 -12 -m ::: *.db

You can install GNU parallel on Ubuntu using the below command

sudo apt install parallel

Note: Passing -m option to the lz4 utility is essential to avoid stdout outputs.

Fix gtest linker error on Windows

2022-03-16T19:05:00.008+11:00

If you are getting the below-mentioned linker error with Google gtest on Windows MSVC, the solution is to define the macro within your project file/Makefile.
Linker error:

error LNK2001: unresolved external symbol "class testing::internal::Mutex testing::internal::g_gmock_mutex" (?g_gmock_mutex@internal@testing@@3VMutex@12@A)

Macro to declare within your project file/Makefile:
GTEST_LINKED_AS_SHARED_LIBRARY=1

Tags: gtest, linker error

Fix slow VNC connection to headless Linux server with intel GPU

2021-05-07T01:14:00.002+10:00

Back in 2018, I had observed that VNC connections to headless Ubuntu 16.04 server (the one without any monitors connected) was extremely slow and laggy. After bunch of experiments, I figured out that the problem was caused due to missing Xorg.conf template

Below solution was tested with Ubuntu 16.04, I am not sure if same problem is still observed with newer Ubuntu versions

Solution:

Ubuntu Force apt to use IPv4

2021-05-06T10:42:00.003+10:00

On U16.04, I found that apt took really long time to update over IPv6.

Enter below command to force the use of IP v4 for apt

echo "Acquire::ForceIPv4 "true";" | sudo tee /etc/apt/apt.conf.d/99force-ipv4 > /dev/null

How to install Dropbox on Linux with single sign on (SSO)

2021-05-05T17:33:00.003+10:00

I had to do mini research to be able to successfully install dropbox on Linux with single sign-on. Here are the steps I followed.

Close all browsers windows.
Open fresh browser window, visit to https://www.dropbox.com/ and login using SSO.
Once logged-in, install dropbox package as usual. I used below steps
- Download the .deb package from https://www.dropbox.com/install-linux
- Enter command sudo dpkg -i <.deb package file path>
Open Dropbox from the installed program files, click OK to install dropbox daemon process.
It should open your browser once again and ask for linking confirmation. Press OK.

Keywords:

dropbox linux enter linking code
Entering Linking Code After Dropbox Install on Ubuntu/Linux

Script to disable automatic updates on Ubuntu 16.04

2021-04-28T11:15:00.003+10:00

I work on Ubuntu with some custom Kernel extensions which needs to be built upon each Kernel updates. Since, it is a dev. environment, sensible option was to lock the packages which I was using for development.

Below script disables automatic package updates on Ubuntu 16.04.x

Note: Do NOT disable security updates on production system!

qDebug log with and without spaces in a single sentence

2021-03-31T01:06:00.001+11:00

Below sample shows how spaces can be disabled/enabled in middle of a single qDebug log.

Keyword: qDebug disable space in middle of log

Mac OS: How to stop/kill Kaspersky Endpoint Security

2021-03-27T14:30:00.050+11:00

Recently all of sudden I had started getting all sorts of internet connecitivity issues on my Office issued Mac book Pro. My internet would stop working all together on my Mac book Pro and the only way to get it working again was to reboot Mac Os.

After some closer inspection, I found that Kaspersky Endpoint Security pushed my company's IT was causing this issue. Since Kaspersky Endpoint Security does not contain graphical user interface to interact with, I had to come up with a way to unload it from system memory.

Below script unloads Kaspersky Endpoint Security Daemon. You need to run it after each reboot. You need to have super user permission.

sudo launchctl unload /Library/LaunchDaemons/com.kaspersky.kav.plist

WARNING: Above command stops Kaspersky Endpoint Security. Enter it only if you know what you're doing!

Qt: Nested QMap example

2021-03-26T22:07:00.005+11:00

I had to recently use nested Qt QMap. Below is a simple C++ code sample which shows how I used nested QMap and initialised using C++ initialiser list.

Install Qt Creator without Qt Account

2021-03-25T23:11:00.006+11:00

I hate using my Qt account whenever I install Qt Creator on any public computers, because Installer automatically stores the login credentials on computer. Once stored, I need to manually delete them later on.

Whilst installing Qt Creator via offline installer, I noticed that installer does not prompt for login whenever there is no internet connectivity. You can simulate this by configuring invalid proxy configuration within the Qt Creator installer.

It's quite straight forward. Click on settings button, and configure 0.0.0.0 as the proxy.

After this you can proceed to install Qt Creator without having to worry about the Qt Account login.

Update:

It seems above trick does not work with Qt Creator 4.15 (at-least on Linux). Qt Creator installer checks for network connectivity at startup. I use below command to override.

sudo bash -c "http_proxy="http://localhost:0" ./qt-creator-opensource-linux-x86_64-4.15.0.run"

Alternatively, you can disable internet on your computer before starting the installer.

How to enable display mirroring over VNC on Ubuntu

2020-07-29T21:45:00.004+10:00

Ubuntu ships within a built-in VNC server, which can be configured to enable promptless screen mirroring over VNC.
Run below script/commands on target Ubuntu system.

How to rename Windows 10 user home folder

2020-07-28T23:41:00.008+10:00

Steps to rename User name

Rename the user name in the Control Panel (Windows Menu → Settings → Accounts).

Steps to rename the home folder under C:\Users

To rename the user's home folder, we first need to create a temporary Admin account in Windows 10.
To create a temporary local Admin user in Windows 10, follow below steps:
1. Go to Windows Menu → Settings → Accounts → Family & Other users → Add someone else to this PC
2. Click on I don't have this person's sign-in information.
3. Select Add a user without a Microsoft account
4. You can leave the password field empty, as this is a temporary account and we will delete this account at the end.
Once a new account is created, change the account type to Administrator
Logout and Login as newly created user from login menu.
Open File Explorer, Go to C:\Users\ and rename the folder under C:\Users\<old_username> to the desired name.
After renaming the folder, now let us map the renamed folder with the user account.

Open regedit from Win + R
Traverse to Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProfileList
Traverse through the profile list and find the matching profile where key ProfileImagePath value contains the previous home folder path. Once found, update the value to match your new folder path.
Example:As shown in below image, I renamed from C:\Users\Administrator to C:\Users\supernova

Create a link from your previous home folder to new one via Command Prompt. This should help us with programs which have stored previous home folder path in their settings.
1. Search for Command Prompt in Windows Menu. Right Click and select run as administrator
2. Create a link from previous folder name to new folder name via mklink command.
  Syntax:mklink /j <old_username> <new_name>
  Examplemklink /j Administrator supernova Where Administrator is my previous folder name.
Delete the temp account created in Step 1.

Installing and using Qt libraries with Conan

2020-07-27T23:02:00.002+10:00

For some reason or the other, I always had Qt installed on my dev machine either by manually compiling it from sources or via apt-get. Recently I started using conan to install Qt libaries and qmake.
After installation however, I could not find an automated way of adding installed Qt binaries to my binary search path. Even after many searches online, I did not find any sample conanfile.txt anywhere showcasing the proper way to install Qt with conan. After going through conan documentation however, I found out that conan generator virtualrunenv can be used to tackle this problem. virtualrunenv generator can be used to add/remove directories installed by conan to your binary search path.
To add Qt binaries installed by conan to your PATH, execute:
source activate_run.sh
To remove them from the search path, execute:
source deactivate_run.sh
By adding virtualrunenv as one of your code generators, you can easily bring/remove qt binaries to/from your search path.
Below is my conanfile.txt which I use to install latest Qt 5.15.x via conan:

[requires]
qt/[>=5.15.0 <5.16.0]@bincrafters/stable

[generators]
qmake
virtualrunenv

Some of the disadvantages of using Conan to install Qt:

Qt installed via conan does not include Qt designer and other binaries. It only includes qmake.
Qt installation via Conan still requires few packages to be manually installed via APT.

More info:

conan virtualrunenv documentation

Windows Batch script to use Qt + Microsoft C++ Build Tools

2020-07-26T23:58:00.001+10:00

I recently started using Qt Creator on Windows with Microsoft C++ build tools. During this process, I created below batch script to open a console window where I can give all Qt + nmake/jom commands.

Script to download latest Qt-Creator nightly development installer

2020-07-25T23:58:00.004+10:00

Here is a script I created to download latest Qt-Creator nightly build installer for Linux. However, it can be modified to download the installer Windows or Mac OS. Replace .run with .exe for Windows, and with .dmg to make it download installer for Mac OS.
You can use above script to download latest stable release as well. Just change the URL to https://download.qt.io/official_releases/qtcreator/ to download latest stable release.

How to uninstall Mac OS Xcode command-line tools

2020-07-23T11:27:00.006+10:00

You can uninstall Xcode command-line tools by manually deleting the directory /Library/Developer/CommandLineTools
You can delete this directory either from Finder App or by entering following command in Terminal App.
sudo rm -rf /Library/Developer/CommandLineTools

Resetting the default command line tools:

Once you remove the directory, enter below command to reset the default command-line tools
sudo xcode-select -r

Apple Developer Docs - How can I uninstall the command-line tools?

Above commands should also help you remove command-line tools from Mac OS auto update.

Before:

After:

How to clear Qt online installer Account credentials

2020-07-22T18:21:00.000+10:00

Now that Qt has stopped hosting offline installers, the only option left is to use Qt online installer.
Unfortunately Qt online installer automatically saves the account credentials without asking, and does not provide any option to avoid auto save. This could be particularly problematic if you are using Qt online installer on a public computer, and you don’t want to keep your account credentials lingering around.
Below are steps to delete Qt online installer account credentials
Qt stores the account credentials in a file named qtaccount.ini
You need to delete this file to remove Qt account credentials from the computer.

Windows:

qtaccount.ini is stored at C:\Users\<User Name>\AppData\Roaming\Qt\
Note: You can enter below shortcut in Windows Run (Win Key + R) to open this directory with File Explorer.
%APPDATA%\Qt\
To delete the file in console, open cmd.exe from Windows menu and enter below command
del %APPDATA%\Qt\qtaccount.ini

Linux:

qtaccount.ini is stored at /home/<User Name>/.local/share/Qt/
To delete this file from terminal, enter below code in terminal
rm /home/$USERNAME/.local/share/Qt/qtaccount.ini

Mac OS X:

Qt Account details are stored at /Users/<User Name>/Library/Application\ Support/Qt/
To delete this file via Terminal, open terminal app and enter below code
rm $HOME/Library/Application\ Support/Qt/qtaccount.ini

Related bug report:

https://bugreports.qt.io/browse/QTBUG-82858

NBN: Why 5GHz WiFi router is critical to get good internet speed

2020-07-21T00:14:00.001+10:00

I have Vodafone NBN on 100Mbps/40Mbps plan and below are my two speed test results taken one after the other at around 19:45 (Which is evening peak hours)

Speed test results when connected with 5GHz WiFi

Speed test results when connected to 2.5GHz WiFi

As you can see, 5GHz WiFi is critical to get full download & upload speed on your NBN.

Fix lldb.exe missing python36.dll error

2020-07-15T23:47:00.004+10:00

I generally use Ubuntu 16.04 as my development machine. Recently I tried to setup a Windows 10 development machine on Virtual machine with Qt 5.15 and Qt Creator 4.12

In this machine, I was getting below error each time I tried to open Qt Creator from the start menu.

Turns out the culprit is LLVM I had installed earlier.

Fix is simple. Download Python 3.6 Windows zip file from python website (I used python-3.6.8-embed-amd64). Extract the downloaded zip file, copy the python36.dll to LLVM bin directory (For me it was C:\Program Files\LLVM\bin as shown below). Press OK if you get any warning prompt.

It feels strange that someone forgot to include a crucial DLL with their installer!

Happy coding..

Bamboo Auto-start script in Linux

2017-11-03T18:49:00.002+11:00

Since there are diverse flavours of Linux distributions out there, Bamboo agent installation does not create a auto-start service automatically during the agent installation.

Using the below mentioned steps you can create a Bamboo auto-start service. Below instructions are tested under CentOS 7, however; they should work for any systemd based Linux systems with minor variations.

Creating the Bamboo service

Login to the Bamboo system console over SSH/directly.
Switch to super user.

su -
Create the bamboo.service file inside the directory /etc/systemd/system. Set the proper file permission.

touch /etc/systemd/system/bamboo.service
chmod 664 /etc/systemd/system/bamboo.service

Enter the following command to insert the bamboo.service file contents

echo "[Unit]
Description=Bamboo startup Agent
After=syslog.target network.target
[Service]
Type=forking
User=buildadmin
ExecStart=/home/buildadmin/Bamboo/bamboo-home/bin/bamboo-agent.sh start &
ExecReload=/home/buildadmin/Bamboo/bamboo-home/bin/bamboo-agent.sh restart &
ExecStop=/home/buildadmin/Bamboo/bamboo-home/bin/bamboo-agent.sh stop &
[Install]
WantedBy=multi-user.target" > /etc/systemd/system/bamboo.service

Note:Here buildadmin is the user who is configured to run the Bamboo. Also ensure that you replace the Bamboo start script location with the actual location where it is installed in your system.

Now you can enable and start the service using the usual systemctl commands.
systemctl enable bamboo.service
systemctl start bamboo.service

Tags: Bamboo, Linux, systemd, auto-start, init-script.

How to enable Incognito mode in Google Chrome

2016-12-01T06:11:00.001+11:00

In case you are unable to see New incognito window option in Google chrome, follow the below steps to enable it back.

Step 1: Open regedit from Windows start menu or by pressing Windows Key + r.

Step 2:Go to the location HKEY_Local_Machine\SOFTWARE\Policies\Google\Chrome.

Step 3: In this location, you will find a key named IncognitoModeAvailability. Right click on this key & press delete button.

Step 4: Restart Google Chrome & Check if Incognito menu option is enabled.

Tags: Google Chrome incognito menu option not shown in Windows 10.

IceRocket Tags: Chrome,Incognito,Windows10

Fixing Ruby Gem installation issue

2016-11-30T06:26:00.000+11:00

Today I tried installing asciidoctor gem & I got into below error.

C:\>gem install asciidoctor
ERROR:  Could not find a valid gem 'asciidoctor' (>= 0), here is why:
          Unable to download data from https://rubygems.org/ - SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (https://api.rubygems.org/specs.4.8.gz)

This error is due to missing SSL certificate in Ruby gem. This error can be fixed by updating Ruby gem to latest version. Follow the below steps.

Simple way

First find the current version of gem via gem --version command
Try updating the gem version via gem update --system
Now check the gem version again gem --version

Manual way

First find the current version of gem via gem --version command
Download the latest gem updater gem file from https://rubygems.org/pages/download
Install the gem using gem install rubygems-update-2.6.8.gem
Install latest version of gem via update_rubygems
Now check the gem version again gem --version

Above should fix your problem with Ruby gem.

Tags: Ruby gem install failure.

Airtel V-Fiber Modem

2016-11-27T07:50:00.003+11:00

Airtel provides Huawei Home Gateway HG630a router/modem for v-fiber. Airtel charges Rs 1000 for this modem (billed at Rs 200/month in 5 installments).

Unlike the other A-DSL routers/modems, you cannot directly login into the web console of this router/modem. So in case you want to set different password for your WiFi or change your SSID, you need to contact Airtel customer care. Airtel would send you a one time password, using which you can set your WiFi SSID & password at http://setup.airtelbroadband.in/

But then you can work around this WiFi setup limitation by connecting Huawei modem to your own WiFi router.

Tags: Airtel, v-fiber, Huawei.

Airtel V-Fiber Speed test

2016-11-26T23:47:00.002+11:00

I let the speed test image do all the talking..

How to get it?

Visit Airtel V-Fiber site & provide your details. They would call you back for upgrade.

What they change?

Just the modem. They will replace old A-DSL modem with the newer model. No change in the wiring at-all. The newer modem has built-in Wi-Fi as well. Remember, you also need to get new A-DSL splitter. Airtel does not provide the same.

How much does it cost?

Airtel charges 1,000 Rs for the modem. Airtel charges this to your monthly bill via 5 monthly installments (200 Rs each moth). Also the new splitter costs about 280 Rs.

What about the monthly plan?

No changes in your monthly broadband plan. My current plan is 1399 Rs for 100GB.

Is it worth it?

Absolutely! Go get it..

Technorati tags: OpenGuru.

How to upgrade to Windows 10 free of cost

2016-11-17T06:42:00.000+11:00

All though the free upgrade offer to users of Windows 7 and Windows 8 has ended, you can still perform free upgrade of your Windows installation via below mentioned trick.

Microsoft is still allowing the free upgrade of Windows 7/8 to Windows 10 for users who are using assistive technologies. Microsoft does not seems to be verifying if the user is actually using any assistive technology during the Windows upgrade process.

How to upgrade?

Visit Microsoft website for users of assistive technologies & download Windows 10 upgrade assistant.

Tags: Windows 10 free upgrade from Windows 7 and Windows 8 via assistive technologies.

IceRocket Tags: Windows10