Managing kernel modules on Linux

Basic Linux Kernel module administration commands

The kernel of a Linux system is the core that everything else in the operating system relies on. The functionality of the kernel can be extended by adding modules to it. As such, a user can fine tune their kernel settings by enabling or disabling modules. This level of granular control is one of the many reasons why users love Linux in the first place.

In this guide, we’ll go over some of the most essential kernel module administration commands on Linux. Knowing these commands will help you understand the components that have been loaded into your system’s kernel, and will also allow you to load, reload, or unload modules in the system kernel.

In this tutorial you will learn:

  • How to administer kernel modules on Linux with commands

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Configuring a VirtualBox shared folder

How to configure shared VirtualBox folder on Linux

After installing a Linux distro into a VirtualBox virtual machine, you may be wondering how to share files between the host operating syste and the virtual machine itself. One of the easiest and most convenient ways to provide this function is by setting up a VirtualBox shared folder.

Essentially this means that a folder on your host machine can be mounted on the virtual machine, where both systems will be able to access files or drop them in the folder. It doesn’t matter what host operating system you’re using, as the instructions will be the same across Linux, Windows, etc.

In this guide, we’ll go through the step by step instructions to configure a shared VirtualBox folder. We’ll also show you how to mount the shared folder on your Linux system, allowing you to easily share files back and forth.

In this tutorial you will learn:

  • How to configure a shared VirtualBox folder on Linux
  • How to mount a VirtualBox shared folder

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Recovering deleted files from a FAT filesystem on Linux

Data recovery of deleted files from the FAT filesystem

Although FAT32 or FAT16 are very old file systems, which is reflected in their poor performance in comparison to other file system alternatives, they are still widely used by many electronic devices. Usually, these devices include USB sticks, digital cameras, camcorders and other peripheral storage devices.

There’s a good chance that you own and store personal data on a device with the FAT filesystem. If you accidentally delete important data from the device, we’ve got good news for you: it can be recovered on Linux.

In this guide, we’ll go over the step by step instructions to recover deleted data from the FAT filesystem on Linux. Read on as we use the testdisk command to perform file recovery.

In this tutorial you will learn:

  • How to create a low level backup of FAT filesystem
  • How to install testdisk tool on major Linux distros
  • How to use testdisk to recover deleted files from FAT

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Retrieving and setting a new UUID for a partition on Linux

How to retrieve and change partition’s UUID Universally Unique Identifier on linux

Hard drive partitions on Linux systems rely on a UUID (universally unique identifier) for unique labels. This is basically a unique string of characters that the operating system will use to identify your hard disk partitions and other storage components.

You can see this for yourself by examining the /etc/fstab file on your own system.

$ grep UUID /etc/fstab

In this guide, we’ll go over several command line methods to retrieve the UUIDs of hard disk partitions. We’ll also show you how to generate UUIDs and change a partition’s UUID.

In this tutorial you will learn:

  • How to retrieve, generate, and change the UUID of a partition

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Getting to know the hardware of your Linux box

Getting to know the hardware of your Linux box

When you buy a new PC, laptop, or server and install a Linux distribution, you want to know what hardware is actually installed in the Linux box and more importantly which piece of hardware is supported by the kernel out of the box and which needs special tweaking with modules to get it to work.

This guide features a list of command line examples which should help you to troubleshoot your hardware and find some information about it. This is not an ultimate troubleshooting guide but certainly will serve as a good starting point. Note that some commands may not be available for your platform by default, and some commands may be specific to certain distributions.

In this tutorial you will learn:

  • How to see what hardware is installed via Linux commands

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List of users on a Linux system

Extract user list from your Linux system

User management is an important part of Linux administration, so it’s essential to know about all the user accounts on a Linux system and how to disable user accounts, etc. In this guide, we’ll show you how to list the current users via command line and GUI. This will include a GNOME desktop environment as well as KDE.

In this tutorial you will learn:

  • How to list users via command line
  • How to list users on GNOME GUI
  • How to list users on KDE GUI

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Learning about the awk command through various command line examples on Linux

Learning Linux Commands: awk

In the case of this article, the Learning Linux Commands: awk title might be a little misleading. And that is because awk is more than a command, it’s a programming language in its own right. You can write awk scripts for complex operations or you can use awk from the command line. The name stands for Aho, Weinberger and Kernighan (yes, Brian Kernighan), the authors of the language, which was started in 1977, hence it shares the same Unix spirit as the other classic *nix utilities.

If you’re getting used to C programming or know it already, you will see some familiar concepts in awk, especially since the ‘k’ in awk stands for the same person as the ‘k’ in K&R, the C programming bible. You will need some command-line knowledge in Linux and possibly some scripting basics, but the last part is optional, as we will try to offer something for everybody. Many thanks to Arnold Robbins for all his work involved in awk.

In this tutorial you will learn:

  • What does awk do? How does it work?
  • awk basic concepts
  • Learn to use awk through command line examples

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Send an email using Telnet

Send an email using Telnet

In this guide, we’ll show the step by step instructions to send an email using Telnet on a Linux system. This a great way to test your mail server configuration such as exim, sendmail or postfix without the need for an email client.

In this tutorial you will learn:

  • How to install Telnet on major Linux distros
  • How to send an email using Telnet protocol on Linux

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Viewing an Excel formatted xlsx file in LibreOffice Calc

Converting xlsx Excel format files to CSV on Linux

Files with the xlsx extension have been formatted for Microsoft Excel. These documents contain columns and rows of data, just like those found in Google Sheets or LibreOffice Calc. This data can be stored as CSV (comma separated values), making it easily readable by various applications or even plain text editors. Due to their proprietary nature, Excel spreadsheets can be difficult to open on Linux systems, making CSV files a much more cross compatible format.

In this guide, we’ll show you a few different methods to convert Excel spreadsheets into comma separated files. This can be done from the command line, or you can open the spreadsheets with LibreOffice and resave them in the desired format, as you’ll see below.

In this tutorial you will learn:

  • How to convert xlsx files to csv via command line with ssconvert
  • How to convert xlsx files to csv via command line or GUI with LibreOffice

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VSZ and RSS columns in the ps command output

ps output – Difference between VSZ vs RSS memory usage

The ps command on Linux systems is a default command line utility that can give us insight into the processes that are currently running. It can give us a lot of helpful information about these processes, including their PID (process ID), TTY, the user running a command or application, and more.

There are two columns in the output of the ps command that don’t get talked about a lot. These are the VSZ (Virtual Memory Size) and RSS (Resident Set Size) columns. Both columns give us information about how much memory a process is using. In this guide, we’ll go over their meanings and how to interpret the data they show us in the ps command on Linux.

In this tutorial you will learn:

  • How to interpret VSZ and RSS numbers in the ps command output

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Disabling the bell terminal sound on Linux

Turn off beep / bell on linux terminal

Working with the terminal using a command line interface is very fast and effective way of doing stuff on Linux systems. But have you tried working with the terminal, listening to some music via headphones and having a terminal warning or tab-completion beep / bell turned ON at the same time? Well, it can be very annoying. Listening to the PC Speaker beeps via headphones is very close to the feeling of hitting your head with a hammer. Even without headphones this beeping bell sound is very annoying.

In this guide, we’ll show you several ways to turn off the terminal beep / bell noise in Linux, without just turning your system volume completely off. These instructions have been tested to work with a variety of major Linux distros.

In this tutorial you will learn:

  • Multiple methods to turn off the bell / beep terminal sound in terminal
  • Turn off beep / bell sound in vim text editor

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Executing remote commands via SSH

Executing commands remotely with ssh and output redirection

The SSH command can be used to remotely login to a server running an sshd daemon. This allows Linux administrators to perform variety of administrative jobs. However, SSH is more powerful than just providing a user with remote shell access, as it can also be used to automate remote command executions, like running simple backups and downloading the backup file locally.

In this guide, we’ll go over a few different command line examples to show how you can execute commands on a remote system via SSH, as well as direct the output back to your local machine.

In this tutorial you will learn:

  • Examples for remote command execution via SSH

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