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Programming Leftovers

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  • LD_PRELOAD: How to Run Code at Load Time

    Today I want to continue the series on using LD_PRELOAD. In previous posts, we covered how to inject a shared object binary into a process, and use that to hijack a library function call to run our own code. This is great when we want to overwrite the behavior of external library calls in a process, but we would have to wait for that call to happen first before our code can run. What if we want to run code before the program even runs from within the target process? Today, we are going to explore how this can be accomplished and look at a few use cases where this could be useful.

  • Qt Creator 4.14.1 released

    This release fixes various issues in various parts of Qt Creator. Please see our change log for an overview of the improvements.

  • Using maps in GNU poke

    Editing data with GNU poke mainly involves creating mapped values and storing them in Poke variables. However, this may not be that convenient when poking several files simultaneously, and when the complexity of the data increases.

  • Bash script to While Loop while Reading Stdin – Linux Hint

    The concept “stream” in a computer applies to something that might move data. Any instruction you are executing in the terminal would be at any position of the flow. These positions can be an origin or an outflow. Let’s get a quick overview of the specific Stdin stream. In Linux, stdin refers to the default or standard input. The input it requires must be a text. To acquire data or information from you, it’s the file handler that your procedure readout. Almost all flows are viewed in Linux as if they are directories. We may read/write information from all of these streams, exactly as you can read/write a document. By using a special file descriptor number related to it provides a great approach to access a document. There have been special values allocated to every one of these throughout the situation of such streams. Stdin has a value of 1.

  • How to Obtain a Bash Substring After a Specified Character – Linux Hint

    In programming, a string is a series of characters, whether as a precise constant or some sort of variable. The characters contained within a string can be any number, digit, or special character.

  • Create Bash Functions with Arguments – Linux Hint

    In programming, a function is an entity that performs an activity when it is called. This function may or may not accept arguments, which are the parameters that determine the activity that a function performs. Many of those who are new to programming might wonder why we even need to create functions when we can simply write a program as-is without breaking it into different parts.

    This is where the concepts of Modularity and Code Reusability come into play. Modularity, or modular programming, is a highly recommended programming approach that breaks code into chunks to enhance readability, which also results in Code Reusability. Code Reusability refers to the ability to reuse a certain piece of code repeatedly, thus avoiding the task of rewriting the code every time it is used.

    Modularity and Code Reusability are why functions are so extensively used in all programming languages, regardless of whether they are high-level or low-level. However, it can be quite tricky to create functions that work with the correct arguments or that accept certain arguments. This article uses several examples to show you how to create Bash functions with arguments in Linux Mint 20.

  • Creating Bash Infinite Loop by Example Scripts – Linux Hint

    An infinite loop in Bash or any other programming language refers to a loop that is continuous i.e., its terminating condition is never met or its executing condition forever stays true. Such loops in any programming language are very simple to write. Whether it is a “for” loop or a “while” loop, it can be made infinite with very slight tweaking in its normal syntax.

    In this article, we will be sharing with you the different ways on how you can conveniently make the “for” and “while” loops infinitely in Bash in Linux Mint 20.

  • How to Break from a Bash While Loop? – Linux Hint

    Loops are an extremely useful means of performing repetitive tasks not only in Bash scripting but also in all other programming languages. It enables us to write a task (that is supposed to occur multiple times) at once and enclose it within any desired loop so that the said task can be performed repeatedly. Different loops are used in every programming language, i.e., multiple types of loops can be used with every programming language. Amongst all types, the most frequently used loops are the “for” loop and the “while” loop.

    A major difference between the execution of the “for” loop and the “while” loop is that in the former one, the incrementing or decrementing variable is specified with the loop whereas, in the latter, that variable is specified after the task that is supposed to be performed repeatedly is stated. The “while” loops appear to be more convenient for the programmers syntactically.

    The concept of infinite loops in every programming language is also very common, i.e., a loop that never terminates and its condition assesses to be always “true”. At times, these loops are written accidentally by the programmers, however, there are situations in which such loops are written deliberately. Either way, there can be certain conditions in which we want that infinite loop to break.

  • How to Create a Bash Function that Returns an Array – Linux Hint

    It may appear at first glimpse that returning an array from a Bash function is not realistic. Considering all the benefits, it can be useful to call multiple methods to construct arrays to split up the process of gathering all the appropriate parameters for a YAD call.

More in Tux Machines

digiKam 7.7.0 is released

After three months of active maintenance and another bug triage, the digiKam team is proud to present version 7.7.0 of its open source digital photo manager. See below the list of most important features coming with this release. Read more

Dilution and Misuse of the "Linux" Brand

Samsung, Red Hat to Work on Linux Drivers for Future Tech

The metaverse is expected to uproot system design as we know it, and Samsung is one of many hardware vendors re-imagining data center infrastructure in preparation for a parallel 3D world. Samsung is working on new memory technologies that provide faster bandwidth inside hardware for data to travel between CPUs, storage and other computing resources. The company also announced it was partnering with Red Hat to ensure these technologies have Linux compatibility. Read more

today's howtos

  • How to install go1.19beta on Ubuntu 22.04 – NextGenTips

    In this tutorial, we are going to explore how to install go on Ubuntu 22.04 Golang is an open-source programming language that is easy to learn and use. It is built-in concurrency and has a robust standard library. It is reliable, builds fast, and efficient software that scales fast. Its concurrency mechanisms make it easy to write programs that get the most out of multicore and networked machines, while its novel-type systems enable flexible and modular program constructions. Go compiles quickly to machine code and has the convenience of garbage collection and the power of run-time reflection. In this guide, we are going to learn how to install golang 1.19beta on Ubuntu 22.04. Go 1.19beta1 is not yet released. There is so much work in progress with all the documentation.

  • molecule test: failed to connect to bus in systemd container - openQA bites

    Ansible Molecule is a project to help you test your ansible roles. I’m using molecule for automatically testing the ansible roles of geekoops.

  • How To Install MongoDB on AlmaLinux 9 - idroot

    In this tutorial, we will show you how to install MongoDB on AlmaLinux 9. For those of you who didn’t know, MongoDB is a high-performance, highly scalable document-oriented NoSQL database. Unlike in SQL databases where data is stored in rows and columns inside tables, in MongoDB, data is structured in JSON-like format inside records which are referred to as documents. The open-source attribute of MongoDB as a database software makes it an ideal candidate for almost any database-related project. 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 the MongoDB NoSQL database on AlmaLinux 9. You can follow the same instructions for CentOS and Rocky Linux.

  • An introduction (and how-to) to Plugin Loader for the Steam Deck. - Invidious
  • Self-host a Ghost Blog With Traefik

    Ghost is a very popular open-source content management system. Started as an alternative to WordPress and it went on to become an alternative to Substack by focusing on membership and newsletter. The creators of Ghost offer managed Pro hosting but it may not fit everyone's budget. Alternatively, you can self-host it on your own cloud servers. On Linux handbook, we already have a guide on deploying Ghost with Docker in a reverse proxy setup. Instead of Ngnix reverse proxy, you can also use another software called Traefik with Docker. It is a popular open-source cloud-native application proxy, API Gateway, Edge-router, and more. I use Traefik to secure my websites using an SSL certificate obtained from Let's Encrypt. Once deployed, Traefik can automatically manage your certificates and their renewals. In this tutorial, I'll share the necessary steps for deploying a Ghost blog with Docker and Traefik.