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today's howtos

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  • How to Install Calibre E-book Server on Ubuntu 22.04

    Calibre is a free and open-source e-book manager. In this tutorial, you will learn to install the Calibre server on an Ubuntu 22.04 machine.

  • Install Sysdig System Visibility Tool on Ubuntu 22.04 -

    This tutorial will take you through how to install Sysdig system visibility tool on Ubuntu 22.04. Sysdig is a simple visibility tool that provides deep visibility into your system.

  • A brief history of looking up host addresses in Unix

    In the beginning, back in V7 Unix and earlier, Unix didn't have networking and so the standard C library didn't have anything to look up host addresses. When BSD famously added IP networking to BSD Unix, that had to change, so BSD added C library functions to look up this sort of information, in the form of the gethost* functions, which first appeared in 4.1c BSD but are probably most widely known in the 4.2 BSD version. Because this was before DNS was really a thing, functions like gethostbyname() searched through /etc/hosts.

    The next step in practice in host lookups was done by Sun, when they introduced what was then called YP (until it had to be renamed to NIS because of trademark issues). To avoid having to distribute a potentially large /etc/hosts to all machines and to speed up lookups in it, Sun made their gethostbyaddr() be able to look up host entries through YP; on the YP server, your hosts file was compiled into a database file for efficient lookups (along with all of the other YP information sources). As a fallback, gethostbyaddr could still use your local /etc/hosts, which was useful to insure that you weren't completely out to sea if the YP server stopped responding to you. People who didn't use YP (which was a lot of us) still used /etc/hosts, and perhaps distributed a (large) local version to all of their machines.

  • I wish that systemd (and everything) would rate-limit configuration warnings

    The obvious reason you're seeing this message is that the 22.04 'oidentd@.service' template service unit specifies the now-obsolete 'StandardError=syslog' setting. You're seeing this message frequently because systemd apparently generates these messages whenever the unit is started and oidentd.socket is set to start it on every connection (ie, oidentd.socket specifies 'Accept=yes', which is also the only time you can have a templated socket service unit).

  • Using Prometheus's recent '@ end()' PromQL feature to reduce graph noise

    Modern versions of Prometheus support a special '@' time modifier on PromQL queries. These let you evaluate a part of the query at a specific, fixed time, rather than at either the 'now' of an instant query or at every step of a range query. In addition to literal times, this can use two special time functions, 'start()' and 'end()', which evaluate to the start and end of a range query.

  • Vim settings I'm using for editing YAML (with a sideline into Python)

    I normally stick with minimal Vim customizations, partly because as a system administrator I'm not infrequently editing files as a different user instead of myself. However, due to Prometheus and other things I'm editing more and more YAML these days, and YAML files have such a rigid and annoying requirement for their indentation and formatting that it's painful to edit them in a stock vi-like Vim setup. Initially I stuck 'modelines' at the top of most of the the Prometheus YAML files, but by default these are ignored if you're root so I had to remember to ':set' them by hand. Recently I decided that enough was enough, so I'd set our Prometheus server up so that YAML editing worked properly.

  • How To Install VirtualBox on Linux Mint 21 - idroot

    In this tutorial, we will show you how to install VirtualBox on Linux Mint 21. For those of you who didn’t know, VirtualBox is a free and open-source hypervisor for x86 and x86-64 virtualization, which the Oracle Corporation develops. Not only is VirtualBox an extremely feature-rich, high-performance product for enterprise customers, it is also the only professional solution that is freely available as Open Source Software under the terms of the GNU General Public License (GPL) version 2. It can be installed on operating systems, including Linux, Windows, Solaris, and macOS.

    This article assumes you have at least basic knowledge of Linux, know how to use the shell, and most importantly, you host your site on your own VPS. The installation is quite simple and assumes you are running in the root account, if not you may need to add ‘sudo‘ to the commands to get root privileges. I will show you the step-by-step installation of a VirtualBox Virtualization on Linux Mint 21 (Vanessa).

More in Tux Machines

today's howtos

  • How to Change Comment Color in Vim – Fix Unreadable Blue Color

    Are you annoyed about the comment color in vim? The dark blue color of the comment is often hard to read. In this tutorial, we learn how to change the comment color in Vim. There are few methods we can use to look vim comment very readable.

  • How to Add Repository to Debian

    APT checks the health of all the packages, and dependencies of the package before installing it. APT fetches packages from one or more repositories. A repository (package source) is basically a network server. The term "package" refers to an individual file with a .deb extension that contains either all or part of an application. The normal installation comes with default repositories configured, but these contain only a few packages out of an ocean of free software available. In this tutorial, we learn how to add the package repository to Debian.

  • Making a Video of a Single Window

    I recently wanted to send someone a video of a program doing some interesting things in a single X11 window. Recording the whole desktop is easy (some readers may remember my post on Aeschylus which does just that) but it will include irrelevant (and possibly unwanted) parts of the screen, leading to unnecessarily large files. I couldn't immediately find a tool which did what I wanted on OpenBSD [1] but through a combination of xwininfo, FFmpeg, and hk I was able to put together exactly what I needed in short order. Even better, I was able to easily post-process the video to shrink its file size, speed it up, and contort it to the dimension requirements of various platforms. Here's a video straight out of the little script I put together: [...]

  • Things You Can And Can’t Do

    And it got me thinking about what you can and can’t do — what you do and don’t have control over.

  • allow-new-zones in BIND 9.16 on CentOS 8 Stream under SELinux

    We run these training systems with SELinux enabled (I wouldn’t, but my colleague likes it :-), and that’s the reason I aborted the lab: I couldn’t tell students how to solve the cause other than by disabling SELinux entirely, but there wasn’t enough time for that.

  • Will the IndieWeb Ever Become Mainstream?

    This is an interesting question, thanks for asking it, Jeremy. I do have some history with the IndieWeb, and some opinions, so let’s dive in.

    The short answer to the question is a resounding no, and it all boils down to the fact that the IndieWeb is really complicated to implement, so it will only ever appeal to developers.

  • How to Install CUPS Print Server on Ubuntu 22.04

    If your business has multiple personal computers in the network which need to print, then we need a device called a print server. Print server act intermediate between PC and printers which accept print jobs from PC and send them to respective printers. CUPS is the primary mechanism in the Unix-like operating system for printing and print services. It can allow a computer to act as a Print server. In this tutorial, we learn how to set up CUPS print server on Ubuntu 22.04.

Open Hardware: XON/XOFF and Raspberry Pi Pico

  • From XON/XOFF to Forward Incremental Search

    In the olden days of computing, software flow control with control codes XON and XOFF was a necessary feature that dumb terminals needed to support. When a terminal received more data than it could display, there needed to be a way for the terminal to tell the remote host to pause sending more data. The control code 19 was chosen for this. The control code 17 was chosen to tell the remote host to resume transmission of data.

  • Raspberry Pi Pico Used in Plug and Play System Monitor | Tom's Hardware

    Dmytro Panin is at it again, creating a teeny system monitor for his MacBook from scratch with help from our favorite microcontroller, the Raspberry Pi Pico. This plug-and-play system monitor (opens in new tab) lets him keep a close eye on resource usage without having to close any windows or launch any third-party programs. The device is Pico-powered and plugs right into the MacBook to function. It has a display screen that showcases a custom GUI featuring four bar graphs that update in real-time to show the performance of different components, including the CPU, GPU, memory, and SSD usage. It makes it possible to see how hard your PC is running at a glance.

Security Leftovers

How to Apply Accent Colour in Ubuntu Desktop

A step-by-step tutorial on how to apply accent colour in Ubuntu desktop (GNOME) with tips for Kubuntu and others. Read more