Flush DNS Cache on Ubuntu 20.04 - Step by Step process ?

This article covers how to flush the DNS cache on Ubuntu. If the sites are not loading properly or you are receiving outdated sites, try to flush the DNS cache to see if the issue resolves. 

Remember, after the DNS cache is flushed, sites will first load slightly slower. 

But once the DNS cache is re-populated, sites will be loaded faster.

Facts about flushing DNS cache on Ubuntu:

1. DNS cache is a temporary database that stores information about previous DNS lookups. 

2. Whenever you visit a website, your OS and web browser will keep a record for the domain and the corresponding IP address. 

3. Flushing DNS cache eliminates the need for repetitive queries to the remote DNS servers and allows your OS or browser to resolve the website's URL quickly.

How to use dns-clean to flush DNS-Cache ?

You can clear the DNS cache is by starting the dns-clean utility. Run the following command in your Terminal to do so:

$ sudo /etc/init.d/dns-clean start

Install Atom Editor on Ubuntu 20.04 - Step by step process ?

This article covers the different methods to install Atom editor on Ubuntu 20.04 system. Atom is an open-source text and source code editor for Windows, Linux, and macOS, developed by GitHub. 

It is called "A hackable text editor for the 21st century" due to being a highly customizable text editor.

To Install Atom Editor using Snap:

1. First, install the Snap package manager on your system if it is not already installed.

$ sudo apt update && sudo apt install -y snapd

2. Then, install Atom editor with the snap command.

$ sudo snap install atom --classic

Install Dropbox on Ubuntu 20.04 - Step by step process ?

This article covers how to install Dropbox on your Ubuntu 20.04 system. Dropbox online storage provides us support for Ubuntu Linux. 

Dropbox provides us online storage to store or backup our data automatically. We use Dropbox to backup our contents with some security and peace of mind. 

In the event of our PCs crash, Our data will be saved and ready to be restored onto server.

To install Dropbox from Command Line on Ubuntu:

1. Install the wget package using the apt command,

$ sudo apt-get update
$ sudo apt-get install wget

2. Dropbox cli version is available for both 32 and 64 bit editions, we will download Dropbox upon out version.

For 32-bit,

$ cd ~ && wget -O - "https://www.dropbox.com/download?plat=lnx.x86" | tar xzf -

For 64-bit, 

$ cd ~ && wget -O - "https://www.dropbox.com/download?plat=lnx.x86_64" | tar xzf -

3. Run the following command to start the Dropbox from .dropbox-dist folder.

$ ~/.dropbox-dist/dropboxd

To manage Dropbox service:

1. Enable dropbox service using command below.

$ sudo systemctl enable dropbox

2. Start dropbox service using command below.

$ sudo systemctl start dropbox

3. Check running of the service using command below.

$ sudo systemctl status dropbox

Password Protect a File Using Vim on Ubuntu - Step by Step process ?

This article covers how to password protect a file using Vim on Linux.  When password protecting a file, make sure you remember it, or else you will not be able to access your file.

You can also use a password management software if you find it difficult to remember passwords. Or visit our guide on how to install Teampass password manager on Ubuntu .

Always remember to appropriately secure text files that could contain secret info such as usernames and passwords, financial account info and so on, using strong encryption and a password.

To install VIM in Linux:

Vim is available in the repositories of most major distributions. 

So, use your distribution package manager to get installed.

For Debian based systems, use apt-get or apt package manager to install vim.

$ sudo apt-get install vim

For RHEL/CentOS based systems, use yum package manager to install vim.

$ sudo yum install vim-enhanced

For Fedora system, use dnf package manager to install vim.

$ sudo dnf install vim-enhanced

For openSUSE system, use zypper package manager to install pass.

$ sudo zypper in vim

For Arch Linux based systems, use pacman package manager to install vim.

$ sudo pacman -S vim

Install R on Ubuntu 20.04 - Step by Step process ?

This article covers R installation on Ubuntu 20.04 system. R is an open-source programming language, R is widely used for performing data analysis and statistical computing. Supported by the R Foundation for Statistical Computing, it is an increasingly popular and extensible language with an active community. R offers many user-generated packages for specific areas of study, which makes it applicable to many fields.

To Install R on Ubuntu:

1. Add the relevant GPG key,

$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E298A3A825C0D65DFD57CBB651716619E084DAB9

2. Add the repository,

$ sudo add-apt-repository 'deb https://cloud.r-project.org/bin/linux/ubuntu focal-cran40/'

3. Run update after this in order to include package manifests from the new repository.

$ sudo apt update

4. Install R with the following command:

$ sudo apt install r-base

If prompted to confirm installation, press y to continue.

Asynchronous Programming in Python - More about this ?

This article covers how to make applications performant and efficiently use CPU cycles and threads. However, it is not all rainbows and unicorns when talking about asynchronous code.

Asynchronous programming is a type of parallel programming in which a unit of work is allowed to run separately from the primary application thread. When the work is complete, it notifies the main thread about completion or failure of the worker thread. 

There are numerous benefits to using it, such as improved application performance and enhanced responsiveness.

On the other hand, A synchronous program is executed one step at a time. Even with conditional branching, loops and function calls, you can still think about the code in terms of taking one execution step at a time. When each step is complete, the program moves on to the next one.

Examples of synchronous program:

1. Batch processing programs are often created as synchronous programs. You get some input, process it, and create some output. Steps follow one after the other until the program reaches the desired output. The program only needs to pay attention to the steps and their order.

2. Command-line programs are small, quick processes that run in a terminal. These scripts are used to create something, transform one thing into something else, generate a report, or perhaps list out some data. This can be expressed as a series of program steps that are executed sequentially until the program is done.