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Jumat, 17 Februari 2023

Downgrading a Package via apt-get

In a situation where a recently upgraded software is causing issues?

While you can always investigate the issue to fix it, at times, going back to the previous working version saves time and effort.

If the new version introduced a bug, you could do nothing on your end, right?

The good thing is that you can easily downgrade an apt package in Ubuntu and Debian.

All you have to do is to use the apt command like this:

sudo apt install package_name=package-version-number

That seems easy enough but how would you get the exact version number? Which old versions are supported? You can get that detail with:

sudo apt-cache policy package_name

Let me explain all this with a real-life example.

Downgrading apt package

Recently, I was updating the Ubuntu server that hosts It's FOSS Community forum.

I did the usual apt update && apt upgrade and things went bonkers by the time updates were installed.

Apparently, the latest version of Docker didn't support the aufs storage driver. To reduce the downtime, I opted to downgrade to the previous Docker version.

Check the currently installed package version

Then check for the available versions that could be installed:

sudo apt-cache policy package_name

It may throw a huge list or just a small one:

If it shows at least one older version than the current one, you are in luck.

Now, you may think that the version number of a package would be composed of just the numbers. But that may not always be the case.

Basically, you copy the entire stuff before 500 (the priority number).

brave-browser:
  Installed: 1.48.158
  Candidate: 1.48.164
  Version table:
     1.48.164 500
        500 https://brave-browser-apt-release.s3.brave.com stable/main amd64 Packages
 *** 1.48.158 500
        500 https://brave-browser-apt-release.s3.brave.com stable/main amd64 Packages
        100 /var/lib/dpkg/status
     1.47.186 500
        500 https://brave-browser-apt-release.s3.brave.com stable/main amd64 Packages
     1.47.171 500
        500 https://brave-browser-apt-release.s3.brave.com stable/main amd64 Packages
     1.46.153 500

Once you have got the package number, use it to downgrade the installed package like this:

sudo apt install package_name=package-version-number

You'll see a warning about downgrading the package, of course.

But once the process completes, your package would have been downgraded to the given older version.

So, hold it, maybe?

So, you just learned to downgrade apt packages. But if you don't pay attention, the package will be upgraded again with the next system update.

Don't want that? You can prevent a package from being updated. Use the apt-mark command like this:

sudo apt-mark hold package_name

Want more details? Check out this article.

I hope this quick tip helps you with downgrading the apt packages when the need arises. Let me know if you have questions or suggestions.

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Kamis, 16 Februari 2023

FOSS Weekly #23.07: Terminal Basics, KDE Plasma 5.27 and Markdown Guide

For years, the focus of It's FOSS has been on desktop Linux. This is the reason why we mostly go for GUI solutions and tools.

Though this is not changing, knowing the basic Linux commands gives you an edge while troubleshooting.

And hence I am starting a new series this week. It's called 'Terminal Basics'. I aim to give you a base for doing some of the common things in the Linux command line.

The tutorials are written in an interactive 'do it while you read it' manner. I have also added simple exercises to practice what you learn. You can further discuss your solutions and doubts in the community forum.

Here's the first part of the series. Even if you are experienced with the commands, please give it a read and provide feedback by replying to this mail or leaving a comment.

💬 Let's see what else you get in this week's issue:

KDE Plasma 5.27 release, among other news
Markdown guides
And more Linux news, open source applications, videos and memes

📰 Linux News Round-up

CrossOver 22.1 arrived at the scene.
Fedora's new Anaconda Web UI installer is looking good.
A proposed change to Google's Go programming language will be controversial.
ONLYOFFICE has added ChatGPT and Zoom integration.
A worrisome report has shed light on over 700 malicious packages in npm and PyPI.
Mozilla has given us a sneak peek at the major UI overhaul of Thunderbird.

🧠 What we’re thinking about

It looks like Linux Lite has integrated an AI helper onto the distro. They may be one of the very first ones to do so!

Linux Lite | AI Helper

AI HelperJerry Bezencon

🗓️

On 15th February 1999, hundreds of computer owners (dominated by Linux users) marched on Microsoft’s offices demanding refunds for the copies of Windows that came pre-installed on their computers. This day came to be known as Windows Refund Day.

🗂️Markdown guides

Markdown is everywhere. You can write technical documents or take personal notes. It can be rendered beautifully on the web so you can write blogs in Markdown. Many applications like Discord also support Markdown syntax for formatting the content.

Here's a beginner's guide to help you learn Markdown.

There are several variants of Markdown. One of them is for creating R programming-related documents. Here are some details on it.

🐧Linux learning resources

I stumbled across a new Bash scripting book that is available for free legally. You can download it from its official GitHub repository.

Download Bash Scripting Book

📹 What we are watching

Take a look at the newly released KDE Plasma 5.27.

📱Application highlights

A minimal-looking software tool with essential features, Design aims to be a nice 2D CAD option for Linux users.

🎫 Event Alert: Open Source Summit North America

Open Source Summit is the premier event for open source developers, technologists, and community leaders to collaborate, share information, solve problems, and gain knowledge, furthering open source innovation and ensuring a sustainable open source ecosystem. It is the gathering place for open-source code and community contributors.

The event will be taking place in May in Vancouver, Canada.

It's FOSS is a media partner of this event. If you are willing to attend the event, you can get a 20% discount on the tickets using coupon code OSSNA23FOSS20.

🤣 Linux Humor

Can any of the current-gen proprietary OSes do that? :P

❤️ Enjoying FOSS Weekly?

Forward it to Linux-using friends and encourage them to subscribe (hint: it's here).

Become a Pro member and show your support 🙏

Join our Telegram channel.

Something else? Share it with me by pressing the reply button.

Enjoy :)

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Rabu, 15 Februari 2023

Beginner's Guide to R Markdown Syntax [With Cheat Sheet]

You probably already know about the lightweight Markdown markup language. Refer to our Markdown guide, if you're new to the concept. Overall, it is a simple and effective language for creating plain-text documents.

However, Markdown may not be enough to make detailed reports or technical documents.

Hence, R Markdown as an interactive file format came into existence back in 2014 thanks to packages like knitr and Pandoc. It combines plain text with in-line R code, helping you make a dynamic document.

To create R Markdown documents, you can use various IDEs and extensions to make it possible. However, the official IDE that helps you do it is RStudio. So, in this article, we will focus on learning R Markdown syntax using RStudio.

💡

If you did not know, R programming language is used for statistical computing, graphics representation, and reporting.

Suggested Read 📖

Setting RStudio

RStudio makes it easy to work with R Markdown by its setup process. You just need to install a package, and you are done for the most part!

Once you have RStudio installed, head to the Tools menu and select the Install Packages option.

On the new dialog box, search for rmarkdown and install it.

💡

To use code chunks like python, you need to install additional packages. RStudio will prompt you to install the required packages when you try to include them in your document.

Once installed, you can start a new rmarkdown document by selecting File > New > RMarkdown.

This will prompt you to add some information regarding the document (metadata for the file). Fill those up.

Or you can create an empty document to start fresh.

RMarkdown Syntax

Since it is just "enhanced Markdown," most syntax remains the same.

There would be some differences when you add things not usually supported with Markdown, like tables, math equations, code chunks, etc.

Here's a quick summary of what we will be covering:

Name of the RMarkdown Block	Proper Syntax
Heading	# Level 1 ## Level 2 ### Level 3 Level 1 ======= Level 2 -------
Emphasis	Italics _Italics_ Bold __Bold__
List	Unordered List * Item * Item + Sub + Sub Ordered List 1. Item 2. Item + Sub + Sub
Code Chunk	Normal Code Block ``` Code Goes Here ``` R Code Block ```{r} R CODE ``` You can use other languages also. Inline `code`
Links	Plain Link: Paste the URL Link with Caption: [Text](URL_Address) Link to a section: [Text](#Name-of-section)
Table	\| Column \| Column \| Column \| \| ------ \| ------ \| ------ \| \| Item \| Item \| Item \| \| Item \| Item \| Item \|
Equations	In line Equations: $Equations$ Display Equations: $$Equations$$
Images	Without Caption: ![](Link-to-Image) With Caption : ![optional caption text](Location-of-image)
Block Quotes	> Type your Block Quotes
Misc	Super Script : Text^Superscript^ Horizontal rule or Page Break: ========= or ---------- For Manual Line break, end line with 2+ spaces

The YAML Header

At the top of a Rmarkdown document, there is a YAML header enclosed within two ---. This block usually contains a title, author, date, and the file type you want to output, defining the final look of the document.

The file type is either HTML, PDF, or Word.

---
title: "Sample"
author: "It's FOSS"
date: "2023-02-08"
output: pdf_document
---

This can be added while setting the new document in RStudio, which is shown in the above section.

Heading

In R Markdown, we can give heading in two different methods. Either we can use the # character for different levels of heading like:

# Heading Level 1
## Heading Level 2
### Heading Level 3
#### Heading Level 4
##### Heading Level 5
###### Heading Level 6

Or, = and - for level 1 and 2 headings, respectively.

Level 1 Heading
===============

Level 2 Heading
---------------

Lists

There are two types of Lists, the first one is an Unordered list, or you could call them bullet points:

* Item 1
* Item 2
                + Sub 1
                + Sub 2
* Item 3

And the second one is the Ordered list, which is the numbered type:

1. Item 1
2. Item 2
                + Sub 1
                + Sub 2
3. Item 3

Suggested Read 📖

Format text within a paragraph

There are several ways to format text.

You can add emphasis to the text like italics or bold using:

Italics: Place the text in between single asterisks or single underscore
Bold: Place the text in between double asterisks or double underscores.

*This is Italicized text*
_This is Italicized text_

**This is Bold Text**
__This is Bold Text__

You can explore on this using our resource on how to add bold and italic text in Markdown.

If you want to add superscript to a text, place the text that should be superscript in between ^ symbol.

Normal Text^super_script^

Or, if you want to add text strike-through, place the text in between two ~~ symbol.

~Strike Through this~~

Adding Code Chunks

Embedding code is the primary purpose of R Markdown. It allows us to add codes in several ways.

Adding Normal code block.

If you want to add a normal code block to separate it from other text, use the syntax below:

```
Your Code Goes Here
```

You can also try adding code blocks with syntax highlighting.

You should append the language in curly braces if you want to add code and embed its output to the document:

```{Language}
Your Code Goes Here
```

Or, you can add inline codes by placing the respective text between ` symbols.

        The `code` is a code

Here's how it should look like:

Links

To add a link as plain text, just paste the link as it is in a line.

https://itsfoss.com

Or, to make a text hyperlink, use the syntax:

[Text](URL Address)

Another way to add a link is, when you want to link to a section of the page. In this case, use the syntax:

[Text](#Name-of-section)

Tables

The syntax for adding tables is similar to that of markdown.

|Column|Column|Column|
| --- | --- | --- |
|Item|Item|Item|
|Item|Item|Item|

📋

Curious to know more? Refer to our guide on creating tables in Markdown.

Images

To add an image, use the syntax:

![](http://example.com/logo.png)

OR

![optional caption text](figures/img.png)

Block Quotes

RMarkdown allows you to add block quotes. To use this, use the > (greater than) symbol in front of the line/paragraph you want to quote.

This is a normal text

> This is a Block Quote

If you want to explore more use cases of blockquote, head to our Markdown quotes guide.

Equations

Using RMarkdown, you can add either equations or display complex LaTex equations.

For example:

In line Pythagorean Theorem: $Equation$

Display Equation: $$Equation$$

Horizontal Rule / Page Break

Use three or more asterisks or dashes to add a horizontal rule /page break.

************

------------

If you want to add a manual line break, end that line with two or more spaces.

Summary

R Markdown is Useful (Cheat Sheet)

Whether you are working with scientific reports or want to create any other type of dynamic document, R Markdown is your best bet to make the most out of Markdown.

Here's a cheat sheet to help you summarize it all:

R Markdown Cheat Sheet

R Markdown Cheat Sheet.pdf

145 KB

💬 Did we miss something that you use with R Markdown? Share your thoughts in the comments down below.

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Login as Root in Ubuntu GUI

By default, Ubuntu disables the root account. You must use the sudo command for any tasks requiring root privileges.

This is for your own security, of course. Using the system as root all the time is like running around with a sword in your hand. It increases the chances of messing up things.

Logging in as root is still common in the servers. On the desktop side, it's quite rare to log in as root. Even Kali Linux has changed it.

And yet, a few desktop users want to log in as root. This is not something advisable but surely doable.

in this guide, I will show you how to log in as a root in your GNOME desktop using Ubuntu.

🚧

I won't advise login as root on the desktop. You have sudo mechanism for all your root needs. Do it only if you have a good enough reason. This tutorial is for demo purposes only. You have been cautioned.

Step 1: Enable root account

You want to log in as root. But the root account is disabled by default. The first step is to enable it.

Change the root account password that will eventually enable the root account for you:

sudo passwd root

It goes without saying that you should not forget the root password.

Step 2: Change GDM configuration

🚧

This part of the tutorial is only valid for GNOME. Please check your desktop environment and ensure that it is GNOME.

Ubuntu uses GNOME by default and GNOME uses the GDM display manager.

To allow log in as root into GNOME, you need to make some changes in the GDM configuration file located at /etc/gdm3/custom.conf.

Make a backup of the config file:

cp /etc/gdm3/custom.conf /etc/gdm3/custom.conf~

In the worst case, if you somehow mess things up, the back up file can be used to replace the existing one from the TTY.

Now, open the GDM file with the following command:

sudo nano /etc/gdm3/custom.conf

And add the following line to allow the root login:

AllowRoot=true

Press Ctrl+X to exit Nano while saving it.

Step 3: Configure PAM authentication

Now, you will have to configure the PAM authentication daemon file, which can be opened by the following command:

sudo nano /etc/pam.d/gdm-password

In this file, you will have to comment out the following line with the # symbol that denies the root access in GUI:

auth   required        pam_succeed_if.so user != root quiet_success

Save changes and exit from the nano text editor.

Step 4: Log in as root

Now, reboot your system:

reboot

At the login screen, select the Not listed option, enter root in username and enter the password that you configured at the beginning of this guide:

Once you log in, it will notify you by saying, "logged in as a privileged user":

That's it! Now, you are running your Ubuntu system as a root.

Things you should know when running the system as a root user

There is a reason why Ubuntu disables a root account by default. Want to know why? Here you have it:

And again, it is not advisable to log in a s root in your desktop Linux system. Please follow the norms and stay away from such (mis) adventures.

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