$$e^{i\pi} + 0.999\ldots = 0$$
The article A Small Equation #55 first appeared on Vielhuber David .
In October 1999, a group led by the then 16-year-old Norwegian Jon Lech Johansen released the DeCSS program to circumvent the Content Scramble System (CSS) DVD playback protection. CSS used 40-bit encryption, the keys to which were distributed to licensed manufacturers, to restrict DVD playback. Because the distribution of the code fell under the US DMCA and […]
The article Code in Prime Numbers first appeared on Vielhuber David .
$$\sum_{k=1}^\infty \fracVielhuber{k^2} = \frac{\pi^2}{6}$$
The article A Small Equation #54 first appeared on Vielhuber David .
$$\fracVielhuber{2} + \fracVielhuber{3} + \fracVielhuber{6} = 1$$
The article A Small Equation #53 first appeared on Vielhuber David .
The rational numbers \(\mathbb{Q}\) appear at first glance to be a continuous whole: between any two fractions, there is always another. But this impression is deceptive: there are sets of rational numbers that are indeed bounded, but whose supremum or infimum simply does not exist in \(\mathbb{Q}\). The reason lies in the existence of irrational numbers such as \(\sqrt{2}\), […]
The post ℚ is incomplete first appeared on Vielhuber David .
PaperMC provides a simple foundation for extending Minecraft server-side with small plugins, without requiring clients to install anything. When developing plugins, the question arises of how to display dynamic information to the player. The answer lies in an often overlooked vanilla feature: the boss bar. Originally intended for end bosses, the boss bar can be repurposed […]
The post Minecraft Bossbars first appeared on Vielhuber David .
The Internet Protocol (IP) is the foundation of all internet applications. Other protocols, such as TCP and UDP, build upon it, transporting services like HTTP(S), email, telephony, and DNS. IPv6 is replacing the outdated transport protocol IPv4 because its relatively small address space of around 4 billion addresses has long been exhausted. IPv6 is now almost ubiquitous and more useful […]
The article IPv6 first appeared on Vielhuber David .
We've all been there: You need to quickly run `git pull` or access a database on a cheap shared hosting package (e.g., at IONOS), but the host doesn't offer SSH access – or only in their more expensive plans. Often, the only option left is the tedious manual FTP upload, which makes deployments unnecessarily complicated and prone to errors. One possible solution […]
The article Git without SSH first appeared on Vielhuber David .
Amazon is the perfect shopping channel for freelancers: fast, affordable, and everything in one place. Amazon has now managed to consistently provide timely and readily available invoices for download (even for purchases on the Marketplace). Whether it's a new laptop, an office chair, or just a quick order of printer paper – the goods can be ordered with just a few clicks, usually via a personal account, […]
The article Amazon and VAT first appeared on Vielhuber David .
$$\fracVielhuber{89} = \sum_{n=1}^{\infty} \fracVielhuber{10^{2n}}$$
The article A Small Equation #52 first appeared on Vielhuber David .
$$\int_{0}^{\infty} \frac{\sin(x)}{x} dx = \frac{\pi}{2}$$
The article A Small Equation #51 first appeared on Vielhuber David .
$$\sqrt[3]{-1} + 1 = 0$$
The article A Small Equation #50 first appeared on Vielhuber David .
Anyone who types `git status` first thing in the morning and then drinks coffee will love this little helper. Especially when developing many web projects in parallel, a concise overview is invaluable: Where is the work tree clean, where are there unmerged changes, and where is a pull/push pending? A small shell tool is all you need – as long as it handles spaces/Unicode in paths robustly […]
The post git status 2.0 first appeared on Vielhuber David .
$$\sum_{n=1}^{\infty} \frac{(-1)^{n-1}}{n} = \ln(2)$$
The article A Small Equation #49 first appeared on Vielhuber David .
There's a beautiful song called "It Is What It Is and It Ain't What Is Ain't" by Cali Rose. This can be simply translated as "It is what it is and it isn't what it isn't." With just a few words, entire worlds of truth can be explored. By varying and combining the two halves, a small […]
The article Language and Logic first appeared on Vielhuber David .
Thunderbird has experienced a remarkable revival since 2022. After years of stagnation, the Mozilla Foundation is once again actively investing in its development. The Supernova initiative (Thunderbird 115+) brought fundamental modernizations such as Rust integration for performance-critical components, a modernized UI based on Web Components, and native Exchange support via the EWS/Microsoft Graph API. For users who rely on Thunderbird to manage extensive […]
The article "Automating Thunderbird" first appeared on Vielhuber David .
$$\lim_{x \to 0} \frac{\sin x}{x} = 1$$
The article A Small Equation #48 first appeared on Vielhuber David .
$$\int_{0}^{\infty} e^{-x^{2}} \, dx = \frac{\sqrt{\pi}}{2}$$
The post A Little Equation #47 first appeared on Vielhuber David .
In October 2019, Python 3.8 introduced the Walrus operator (:=) via PEP 572, sparking one of the biggest controversies in the history of the programming language. The debate was so bitter that Python creator Guido van Rossum resigned from his position as BDFL (Benevolent Dictator For Life) in July 2018, even before the release. […]
The post Walrus Operator in PHP first appeared on Vielhuber David .
$$\fracVielhuber{89} = \sum_{n=1}^{\infty} F_n \cdot 10^{-(n+1)}$$
The post A Little Equation #46 first appeared on Vielhuber David .
$$\int_0^1 x^x \, dx = \sum_{n=1}^{\infty} (-1)^{n+1}/n^n$$
The post A Little Equation #45 first appeared on Vielhuber David .
You're on the phone with a friend in the USA on a freezing cold winter day. "It's minus 40 degrees here!" you both exclaim simultaneously. Normally, this would clarify who means Celsius and who means Fahrenheit—but not at this particular temperature. Why is that? This point is the only temperature at […]
The post Of Celsius and Fahrenheit first appeared on Vielhuber David .
$$\frac{d}{dx} \left( x^n \right) = nx^{n-1}$$
The post A Little Equation #44 first appeared on Vielhuber David .
Most graphical file managers don't sort strictly lexicographically, but rather use "natural" sorting. Blocks of numbers in the name are interpreted as numbers – the larger block of numbers wins, even if the opposite would be true alphabetically. The idea behind natural sorting: What people usually want is "9 before 10," "Chapter 2 before Chapter 10"; without leading zeros [...]
The post Confusion in the natural sort order appeared first on Vielhuber David .
$$\frac{d}{dx}(e^{x^2}) = 2xe^{x^2}$$
The post A Little Equation #43 first appeared on Vielhuber David .
Anyone who runs jobs in the Windows Task Scheduler will sooner or later encounter unexplained runtime differences. A PHP script that runs in 5 minutes on the command line suddenly takes 20 minutes when executed via the Windows Task Scheduler. Same user, same permissions, same code – four times the execution time. What was going on? After hours of debugging, Process Monitor [...]
The post Priority in Windows Task Scheduler first appeared on Vielhuber David .
$$\sqrt[3]{-1} = -1^{\frac{2}{3}}$$
The post A Little Equation #42 first appeared on Vielhuber David .
$$\zeta(2) = \frac{\pi^2}{6}$$
The post A Little Equation #41 first appeared on Vielhuber David .
$$e^{i\pi} + 0.5\sqrt{2} = -1 + 0.5\sqrt{2}$$
The post A Little Equation #40 first appeared on Vielhuber David .
$$\zeta(3) = \sum_{n=1}^{\infty} \fracVielhuber{n^3} \approx 1.202$$
The post A Little Equation #39 first appeared on Vielhuber David .
$$\sqrt[3]{2} \cdot \sqrt[3]{4} = \sqrt[3]{8}$$
The post A Little Equation #38 first appeared on Vielhuber David .
$$\int_{0}^{\infty} \frac{\sin x}{x} dx = \frac{\pi}{2}$$
The post A Little Equation #37 first appeared on Vielhuber David .
$$1 + 2 + 3 + \ldots = -\fracVielhuber{12}$$
The post A Little Equation #36 first appeared on Vielhuber David .
$$\int_{0}^{\infty} \fracVielhuber{x^4+1} \, dx = \frac{\pi}{4\sqrt{2}}$$
The post A Little Equation #35 first appeared on Vielhuber David .
$$\int_{0}^Vielhuber x^{-x} \, dx = \sum_{n=1}^{\infty} \fracVielhuber{n^n}$$
The post A Little Equation #34 first appeared on Vielhuber David .
$$\sqrt[3]{x^3} = |x| \quad \forall x \in \mathbb{R}$$
The post A Little Equation #33 first appeared on Vielhuber David .
$$\fracVielhuber{89} = 0.\overline{011235955056179775280898876404494382}$$
The post A Little Equation #32 first appeared on Vielhuber David .
The continuous decline in the price of computing power—two orders of magnitude per decade—has fueled deep learning models enormously since 2010. Larger networks plus more data seemingly reliably delivered ever-higher scores on common benchmarks—and fueled the hope that scaling alone would inevitably lead to AGI. As early as 2019, François Chollet introduced the ARC-AGI benchmark for measuring intelligence. […]
The post The ARC-AGI Benchmark first appeared on Vielhuber David .
The sender's email address is still a good indicator of whether something is spam or not. By default, it's not intuitive in Microsoft Outlook Desktop to expand the view to include a column that shows the specific email address instead of the name. Microsoft hasn't yet implemented this feature as an easy option—yet [...]
The post Show sender email address in Outlook first appeared on Vielhuber David .
$$\sqrt[3]{1728} = 12$$
The post A Little Equation #31 first appeared on Vielhuber David .
$$\int_{0}^Vielhuber x^{-x} dx = \sum_{n=1}^{\infty} \fracVielhuber{n^n}$$
The post A Little Equation #30 first appeared on Vielhuber David .
$$1 + 2 + 3 + \cdots = -\fracVielhuber{12}$$
The post A Little Equation #29 first appeared on Vielhuber David .
$$\sqrt{-1} \cdot \sqrt{-1} = -1$$
The post A Little Equation #28 first appeared on Vielhuber David .
$$\int_{0}^Vielhuber \fracVielhuber{1+x^2} \, dx = \frac{\pi}{4}$$
The post A Little Equation #27 first appeared on Vielhuber David .
In the digital age, data protection, security, and unrestricted access to information are more important than ever. Whether for companies, freelancers, or private individuals – the use of proxy servers offers numerous advantages that go far beyond mere IP masking. Especially in times of increasing censorship, regional blocks, and sophisticated anti-bot systems, powerful proxies are an essential tool for efficient and […]
The article Why proxies have become indispensable in everyday digital life first appeared on Vielhuber David .
In times of HTTPS-only browsers, SameSite cookies, and realistic development conditions, it's important to work locally with real SSL certificates. Let's Encrypt has pioneered this – with the help of certbot and Cloudflare, creating and renewing wildcard certificates is quick and easy. This allows you to access [...]
The post SSL in local development environment first appeared on Vielhuber David .
1. Demystifying VPN Technology and Its Role in Protecting Online Privacy Imagine a secret passageway, mysterious and secure; that's what Virtual Private Networks, or VPNs, represent in the digital world. These little wonders act like a protective layer, encrypting your data and keeping out prying eyes. Think of it this way […]
The post Internet Security: How VPNs Are Changing Online Privacy and Security appeared first on Vielhuber David .
$$\sqrt[3]{-1} = \fracVielhuber{2} + i\frac{\sqrt{3}}{2}$$
The post A Little Equation #26 first appeared on Vielhuber David .
"A machine can have a large memory, but it cannot think - unless we teach it." - Alan Turing. Modern AI models such as GPT-4 or Llama are based on huge data sets and complex mathematical structures. But what is really behind them? In this article, we look at the key components that are needed [...]
The post Building a Large Language Model yourself first appeared on Vielhuber David .
OpenStreetMap (OSM) is a free world map that is created jointly by people all over the world - free, open and independent. While Google Maps, as the market leader, is often the first choice for digital maps, OSM relies on a completely different principle: a collaborative community that collects, improves and makes geographical data available free of charge. Why […]
The post Hosting OpenStreetMap yourself appeared first on Vielhuber David .
Long announced - now reality: Microsoft has switched off password authentication for certain protocols in Exchange Online in favor of oAuth2 from September 2022. The GitHub issues of many libraries and backup scripts make it clear that the changeover caught many administrators off guard. Below we show a way how to use oAuth2 with PHP via [...]
The post Accessing Exchange/Office 365 with PHP first appeared on Vielhuber David .
$$\frac{d}{dx}(x^x) = x^x(\ln x + 1)$$
The post A Little Equation #25 first appeared on Vielhuber David .
$$\fracVielhuber{998001} = 0.\overline{000001}$$
The post A Little Equation #24 first appeared on Vielhuber David .
$$\sum_{n=1}^{\infty} \fracVielhuber{n^2} = \frac{\pi^2}{6}$$
The post A Little Equation #23 first appeared on Vielhuber David .
Is the time not right? Did you send your email too early? Delaying emails can be useful in many situations: whether to give yourself time to check something or to manage your own workload effectively - timing can be crucial. Here are three ways you can delay sending emails and optimize your own communication. Outlook Microsoft […]
The post Delayed email sending appeared first on Vielhuber David .
Browser automation plays a major role in areas such as web scraping, automated testing and interacting with web applications. Until now, Puppeteer, for example, has been used for this. With the advent of AI, new opportunities are now opening up to make browser automation more intuitive and less maintenance-intensive - the stage is set for Stagehand. To clarify how it works, we want to […]
The post Controlling browsers with AI first appeared on Vielhuber David .
$$\int_0^\infty e^{-x^2} \, dx = \frac{\sqrt{\pi}}{2}$$
The post A Little Equation #22 first appeared on Vielhuber David .
Xdebug is a powerful debugging and profiling tool for PHP that helps us analyze and optimize PHP applications. It supports features such as step-by-step debugging, performance measurement and stack tracing, which makes troubleshooting much easier and provides better insight into the code. Below is a small setup guide for using it within VSCode. Installing Xdebug We will install Xdebug as an example […]
The post Debugging in PHP with Xdebug appeared first on Vielhuber David .
Imagine two identical cups - one filled with coffee and the other with milk, both at the same level. A teaspoon of coffee is now scooped from the coffee cup into the milk cup and stirred. Then a teaspoon of the mixture from the milk cup is poured back into the coffee cup. Which cup will then contain […]
The post About Liquids first appeared on Vielhuber David .
Commit messages in Git are often neglected. Many people see them as a necessary evil to save changes. However, meaningful commit messages are a decisive factor for the success of a project: They ensure that changes are easy to track, efficient team collaboration and faster troubleshooting. No reason to automatically create commit messages with the help of AI [...]
The post Git Commit Messages with ChatGPT appeared first on Vielhuber David .
$$1 + 2 + 3 + \ldots + 99 + 100 = \frac{100 \times 101}{2}$$
The post A Little Equation #21 first appeared on Vielhuber David .
February sometimes has an unusually pleasing shape on the calendar. For example, in February 2021, one could experience such a moment, seeing a "perfectly rectangular February". This rare effect occurs when February has exactly \(28\) days and February 1st falls on a Monday. But how often does this actually happen and […]
The post The Rectangular February appeared first on Vielhuber David .
CSS is still confusing for most of us: it has hundreds of poorly named properties, each of which can affect the result in a non-intuitive way. Vertical positioning of elements in web development is tricky and has often caused headaches in the past. But fortunately those days are over. It's hard to believe: […]
The post Vertical Centering in CSS appeared first on Vielhuber David .
CSS transitions are a great way to create interactivity. All you have to do is apply transition to the initial state of an element and the browser will animate the transition between the two states. However, transitions for intrinsic element sizes like auto have been a problem for web developers for decades, and the only way to do this was to calculate the height dynamically using JavaScript. One […]
The post Animating height: 0 to height: auto with CSS appeared first on Vielhuber David .
There is no \(n \in \mathbb{Z}^+\) such that \(0 < n < 1\). Proof: Let us assume that this statement is false. Then there is a \(n \in \mathbb{Z}^+\) such that \(0 < n < 1\). Let us consider the set \(S := \{ m \in \mathbb{Z}^+ : 0 < m < 1 \}\). Since \( n […]
The post There is no integer between 0 and 1 appeared first on Vielhuber David .
In 1950, physicists George Gamow and Marvin Stern noticed an interesting phenomenon: Gamow, who had an office on the first floor of a six-story building, noticed that the next elevator that arrived went down in five out of six cases, even though it wanted to go up. Stern, who worked on the fifth floor, observed the opposite. The elevator […]
The post Elevator Paradox first appeared on Vielhuber David .
A Quine program, or quine, is a program that outputs its own source code when run. A quine must not "step out of itself" by, for example, printing out the contents of the file it is contained in or using introspective capabilities to print out its own representation. Instead, it must compute its own source code. The classic way to create such a program is in […]
The post Quine first appeared on Vielhuber David .
Powerful tools like logrotate make the work of rotating log or backup files much easier. The files are rotated after a certain period of time or when they reach a certain size. If you don't have this tool available on a remote server and can only execute remote SSH commands, you can do it yourself with a small Bash script [...]
The post File rotation with Bash script first appeared on Vielhuber David .
$$\frac{\sin x}{x} \to 1 \text{ as } x \to 0$$
The post A Little Equation #20 first appeared on Vielhuber David .
In the world of numbers, one often comes across surprising patterns that can be both baffling and illuminating. One such curiosity is Benford's Law, also known as the Law of the First Digit. This mathematical phenomenon describes the frequency distribution of the first digits in many real-world data sets and offers interesting insights into the nature […]
The post Benford's Law first appeared on Vielhuber David .
$$\int_{0}^{\infty} \frac{\sin x}{x} \, dx = \frac{\pi}{2}$$
The post A Little Equation #19 first appeared on Vielhuber David .
I have two children and a son who was born on a Thursday. What is the probability that I have a daughter? Let us denote the days of the week with the numbers \(1, 2, … , 7\) with \(1\ =\) Monday, \(2 =\) Tuesday and so on. Now we can write the event "on day \(n\) a boy was born" as […]
The post Paradoxical Probability Theory first appeared on Vielhuber David .
Assuming that the number \(Y\) of all people who have ever been born and will be born at some point is finite, let \(x\) be your absolute position from the beginning of the list. Then \(0 < \frac{x}{Y} \leq 1\). We can now say with a probability of \(95\%\) that you are among the last \(95\%\) of all people ever born, […]
The post The Doomsday Argument appeared first on Vielhuber David .
The following sentence is known as the "drinker's paradox": "There is someone in the bar such that if he or she drinks, everyone in the bar drinks." It does not matter whether this one person incites others to drink or whether some other back door exists, as we will see shortly. It is a […]
The post Drinker's Paradox first appeared on Vielhuber David .
A boy thinks of a number that is \(1\), \(2\) or \(3\), and a girl is then only allowed to ask one question about this number. The boy can only answer with "yes", "no" or "I don't know". By cleverly asking the question, the girl manages to find the correct number that the boy thought of.
The post Guessing Numbers appeared first on Vielhuber David .
$$\int_{0}^Vielhuber x^x \, dx = \sum_{n=1}^{\infty} \fracVielhuber{n^n}$$
The post A Little Equation #18 first appeared on Vielhuber David .
Imagine that one day you receive a mysterious package with no sender. Curious, you open the package and find a ring, which you give to your daughter. Decades later, she is the one who can send objects into the past using a wormhole. She does this with the ring that you once gave her, [...]
The post Object without origin appeared first on Vielhuber David .
As an alternative to the highly valued Travis CI, GitHub Actions has been available for some time. As a continuous integration tool, it is very well integrated into the GitHub code platform and is now running very stably. GitHub Actions are based on YAML configuration files that are stored in the repository in which the workflow is to be executed. Below is […]
The post CI with GitHub Actions appeared first on Vielhuber David .
In 1961, James and Stein published the paper "Estimation with Quadratic Loss". Take normally distributed data with an unknown mean \(\mu\) and variance \(1\). If you now choose a random value \(x\) from this data and have to estimate the mean \(\mu\) on this basis, intuitively \(x\) is a reasonable estimate for \(\mu\) (since there is a normal distribution, […]
The post Stein's Paradox first appeared on Vielhuber David .
UUIDs (Universally Unique Identifiers) are 128-bit values used in databases to uniquely identify table entries. They are represented as a hexadecimal string divided into five groups separated by hyphens (example: 09fe49b3-4d2b-471c-ac04-36c9e706b85f). There is a lot of discussion about the advantages and disadvantages of UUIDs in databases - in distributed systems they are unavoidable. In […]
The post UUIDs in databases first appeared on Vielhuber David .
Sensitive data or excessive storage space consumption: There are good reasons to want to change the Git history. In this blog post I explained how to use BFG to delete files from the Git history. One weak point of BFG is the lack of support for direct paths, so you cannot specifically delete files or folders in subfolders [...]
The post Cleaning up Git history part 2 first appeared on Vielhuber David .
tl;dr: Manually set values or the default values of WP_MEMORY_LIMIT/WP_MAX_MEMORY_LIMIT have no effect if WP_MEMORY_LIMIT/WP_MAX_MEMORY_LIMIT is less than or equal to PHP's memory limit (hereafter called memory_limit). They are designed to dynamically increase low values of memory_limit to a recommended minimum.
The post Memory Limit in WordPress appeared first on Vielhuber David .
If you embed a third-party iframe (for example a widget), you cannot access its content using CSS or JavaScript (due to the so-called same-origin policy). However, there is a very simple method to still modify any code (including in other files that are loaded within the iframe). To do this, you direct the […]
The post Quick Tip: Modify Iframe appeared first on Vielhuber David .
ANTON is one of the most popular learning apps for students in grades 1-10. The gamification aspect of earning coins may seem strange to adults at first glance - but it noticeably increases the motivation of not only my children. You even save up a small "cushion" of coins that you don't touch. [...]
The post Coins in the ANTON app first appeared on Vielhuber David .
The German IBAN consists of the country code (DE), a two-digit check digit (according to ISO 7064), the bank code (8 digits) and the account number (including sub-account number, 10 digits, missing digits filled with leading zeros) and is therefore 22 digits long. To calculate the check digit, the so-called BBAN (bank code and account number) and the numerical country code \(1314\) for Germany and the check digit […]
The article On the robustness of the IBAN first appeared on Vielhuber David .
At the last family evening, the children enthusiastically brought the game Dobble (in the Harry Potter edition) to the table. After the 5th lost round (without my card being visibly hit with the playing card), I was told, to my astonishment, that every player can always find a hit in every round. But my disbelief was only extinguished with […]
The post Mathematics in the game Dobble appeared first on Vielhuber David .
You know: The expected time between two Bitcoin blocks is on average \(10\) minutes. Now you make an important Bitcoin transaction and wait anxiously to see if and when it appears in the next block: e50bfacc95975a4e7545d83d8954645f Since you did not check when the previous block was completed, you actually expect on average \( \frac{t}{2} = \frac{10}{2} = 5 \) minutes […]
The post Bitcoin Block Time appeared first on Vielhuber David .
$$\int_{0}^{\infty} e^{-x^2} dx = \frac{\sqrt{\pi}}{2}$$
The post A Little Equation #17 first appeared on Vielhuber David .
In short, online casino web development refers to the creation of graphic elements for online casino websites. Web design includes everything from animations to writing plain text. The requests of players and operators when it comes to online casinos are often complicated and varied. Thus, web development in online gaming can become a complicated process, […]
The post How important is the design of my casino website? appeared first on Vielhuber David .
In the RKI weekly report from November 11, 2021, page 22 states that \(36\%\) of the over 60-year-old corona patients in the intensive care unit were already fully vaccinated. In this age group, \(87\%\) were fully vaccinated at that time (see page 18). Let: \(G\): Over 60-year-old is vaccinated \(U\): Over 60-year-old is unvaccinated \(I\): Over 60-year-old is in intensive care Now $$P(G) = 0.87 \wedge […]
The article Corona Mathematics first appeared on Vielhuber David .
Finite decimal numbers are called decimal fractions because they are another representation for fractions with powers of ten in the denominator. So: $$\frac{z}{n} = \frac{q_1}Vielhuber + \frac{q_2}{10} + \dots + \frac{q_k}{10^k}$$ with \(k \in \mathbb{N}\) and \(q_k\) the \(k-1\)th place to the right of the decimal point. Now: $$\frac{z}{n} = \frac{10^k \cdot q_1 + 10^{k-1} q_2 + \dots + […]
The post Decimal Fractions appeared first on Vielhuber David .
To quickly install and change Node versions, we recommend using nvm. If you want to explicitly specify the required Node version in a project, create a file called .nvmrc with the exact version number (e.g. "12.10.0") in the same folder where the package.json is located. If you now change to the folder, the following extension of the file ~/.bash_profile [...]
The post Quick Tip: Automatically switch Node versions appeared first on Vielhuber David .
Ever since responsive web design came into existence, developers have been asking for the ability to style DOM elements based on their actual size rather than the size of the browser viewport (using media queries). In fact, container queries (originally element queries) are probably the most requested CSS feature that still doesn't exist in browsers […]
The post Using Container Queries Today first appeared on Vielhuber David .
Sensitive data such as passwords should be stored in .env files and, if possible, not in Git repositories. But it has probably happened to all of us at least once by accident: quickly publishing a nice Google Maps JS API script on GitHub Gists (as "public") and accidentally not concealing your own private Maps API key. Fortunately, […]
The post Cleaning up Git history first appeared on Vielhuber David .
If you want to cut out an image using an SVG, we recommend using the CSS property clip-path. The following script solves some of the awkward barriers: The SVGs can be saved using Illustrator, you can specify the (relative or absolute) URL of an SVG (Chrome only natively supports inline SVGs to date) and the cutout is also completely […]
The post Cutting SVGs from images using clip-path appeared first on Vielhuber David .
Using the meta_query attribute in the powerful WordPress class WP_Query, you can filter posts that have certain values in their meta fields. If you have created a multi-line meta field (e.g. using Advanced Custom Fields) and only want to find posts that contain a certain value in this field separated by line breaks, we recommend the REGEX world of […]
The post Quick Tip: WP_Query & Multiline Fields appeared first on Vielhuber David .
In a previous article, I described how you can easily integrate animations from Adobe Animate into a website using an APNG export. There is also the native way using HTML5 Canvas Export, but anyone who has worked with it will notice that it is full of problems (inadequate responsiveness [...]
The post Embedding Adobe Animate animations natively appeared first on Vielhuber David .
Normally, when integrating Google Maps, you work with the Maps JavaScript API, which requires an API key and can cause significant costs if the number of hits is high. There are great alternatives such as mapbox or OpenStreetMap, but they do not yet have the same range of features as Google. Google itself also offers a way without an API key via the […]
The post Google Maps without API Key first appeared on Vielhuber David .
Browser support for animated PNG files is now so good that animations created with Animate CC can easily be exported to APNG and then integrated into a web page using a simple <img> tag. This is a simple and high-quality alternative to the publishing method in Animate CC, which generates JavaScript. Below are […]
The post Adobe Animate APNG Export appeared first on Vielhuber David .
If you want to extend the native WordPress search to include meta fields, for example, it is advisable to take a look at the fired filters. To ensure that pagination continues to work and to avoid undermining future improvements in the search, the posts_search hook is recommended. The following code uses the REGEXP and ExtractValue functions to extend this search to include posts that appear in all […]
The post Extend WordPress Search appeared first on Vielhuber David .
The SISTRIX tool is, alongside Xovi, the most widely used SEO analysis program in Germany. The visibility index has become a quasi-standard for the visibility of a page in Google search. The parameters that are used to calculate it are explained here and here and here and here and here, for example, but […]
The article Calculating the SISTRIX Visibility Index first appeared on Vielhuber David .
When Kurt Gödel published his famous incompleteness theorems in 1931, it shook the foundations of mathematical logic: He disproved that all axioms that can be set up as a possible basis for proving all statements about numbers are inevitably incomplete - and destroyed Hilbert's dream of proving the consistency of mathematical theory. The […]
The post Gödel's Masterpiece first appeared on Vielhuber David .
Despite all the data protection concerns, WhatsApp is still the Germans' favorite messenger app. In addition to the special WhatsApp Business app, Facebook has also created an official interface, the WhatsApp Business API, to make it more interesting for companies. If you want to send WhatsApp messages programmatically from your web application, there are other ways. The official way […]
The post Using WhatsApp via API first appeared on Vielhuber David .
If you use elements such as overlays (which is the norm in times of GDPR activism) and want to blur the area behind the overlay, for example, you often come across the problem of the stacking context. If you have absolutely or fixedly positioned elements, for example, they are suddenly displayed differently than without a filter applied. But there is a solution. The following […]
The post Blur page using CSS behind overlay appeared first on Vielhuber David .
You don't need to use a powerful tool like Google Optimize for simple URL split tests, you can also solve the Apache problem using .htaccess. The following code snippet distributes visitors equally between the two versions for the two pages https://vielhuber.de/test1.php (variant 1) and https://vielhuber.de/test2.php (variant 2). The randomization is based on the current server time. 4ab46765cc5456fb96ad18db79dcfaaa Returning visitors see (per session […]
The post Quick Tip: Split Testing with Apache appeared first on Vielhuber David .
Curly brackets are used when notating function definitions with case distinctions. We are looking into the simple question of whether this representation can be eliminated and the function can be reduced to a notation that does not require it. For example, can the function $$f: \mathbb{R} \to \mathbb{R}, f(x) = \left\{\begin{matrix} 42, & \text{if } x = 0 […]
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When visualizing data in Google Sheets, you come across the problem that the \(x\) axis cannot automatically fill in the missing gaps for text values (such as calendar weeks). To solve the problem, you generate a continuous date series, count the cells that occur yourself and then visualize the cumulative totals. The standard diagram that the […]
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Find the error: 72aaa2dbd201d49fc2ee429ebf68f15b PHP caches the return values of stat() and thus, for example, the result of filesize(). If it is called multiple times on the same file, it always returns the value of the first call, so in our case only the first three letters are read out. To change this behavior, it is generally recommended to cache the return values of stat() after each […]
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As part of its Google Cloud, Google offers the Google Translation API with a usage-based cost structure. There is also an undocumented API that can be used without a key, but which stops working after just a few requests. When using the website translation function in Google Chrome, it is noticeable that pages are translated in very good quality without any noticeable limitations [...]
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If you take a look at the technical innovations of the last two years, you will repeatedly find words like smart technologies or artificial intelligence (AI). But if you take a closer look, you will see that most devices are still far from artificial intelligence. Smart home systems such as those from Amazon or Google are particularly often associated with AI. […]
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If you link Github with Composer, it is mandatory to assign a version number via git tag. The following command line command determines the current tag and increases it (according to SemVer) by one version number. For example, version 1.1.0 follows 1.0.9. If no tag is assigned, the version is automatically tagged with 1.0.0. Tools such as flimsy or git hooks […]
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$$\frac{d}{dx}e^x = e^x$$
The post A Little Equation #16 appeared first on Vielhuber David .
Unfortunately, MySQL does not offer an ALTER TRIGGER function. To edit an existing trigger, you must first delete it and then generate a new one. The CREATE TRIGGER statement can be read indirectly via the information_schema. This allows us to change triggers in a roundabout way. To do this, take the result of the following SELECT command (change the database and trigger name first) [...]
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Since ES6, VanillaJS has been on a par with the original jQuery in almost all areas and is now far superior. It is therefore worth gradually migrating legacy code away from jQuery. However, you have to be careful when triggering manual change events. For example, document.addEventListener does not trigger on jQuery.change(). The following overview summarizes the special features. d35c23821164cbe64a509d94ce0df8be
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The setting of cookies by your own or third-party scripts can be finely controlled using PHP and JavaScript. Although this is not a sufficient solution for the implementation of cookie solutions following the court ruling against Planet49 (here it is crucial that tracking tools such as Google Analytics do not track in the first place and thus subsequently [...]
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In order to save power or reduce your own surveillance paranoia, it is advisable to completely disconnect devices on your computer that are not in use from the power supply. Devices such as sound boxes or webcams can be deactivated/activated in the traditional way via the device manager. The whole thing also works via script. In the past, the standard way to do this was devcon. Windows 10 now offers […]
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Skype has a nice, somewhat hidden function: During video transmissions, you can easily blur the background automatically by clicking on the video button and using the "Blur my background" function. With the help of artificial intelligence, this works with any camera, even without depth information. The whole thing then looks more professional and blurs out private things or things that are unimportant to the conversation [...]
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For websites based on WordPress, Joomla or Laravel, for example, and which do not have user-specific content, it is recommended to keep all pages in a static HTML cache and only regenerate the cache manually (or automatically) when changes are made in the backend. However, if the page contains dynamic content that depends on sessions and cookies or language and location [...]
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SVGs play a central role in today's web. They have not only replaced icon fonts, but also offer the possibility of manipulation via CSS or JavaScript. If you want to save a vector graphic for the web from Adobe Illustrator as an SVG, you have to make a few settings to avoid pitfalls and reduce loading times, which I will explain in the following [...]
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Project Euler is a series of exciting programming problems that often have a mathematical background. The problems are often posed in such a way that you have to develop sophisticated algorithms to reach your goal in a reasonable time. Today we are solving problem 15: Lattice paths, where you can find the solution using simple combinatorial means. The question […]
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Since version 3.7, WordPress has implemented background updates natively and activated them automatically for minor releases. You can use filters to control the behavior of what is automatically updated. However, a permanent, fully automatic installation of all minor, major, plugin, theme and translation updates is not planned, but can easily be accomplished in other ways. There are numerous plugins that […]
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In order to extend formulas to entire columns within Google Sheets, we recommend using the useful ARRAYFORMULA function. Unfortunately, this does not work in combination with some other important functions such as QUERY or INDIRECT, which is why you have to program the logic completely individually using Google Apps Script or, alternatively, manually copy the formula right up to the […]
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Simpson's paradox is one of the most easily understood and at the same time astonishing phenomena in statistics. It occurs whenever groups of data show a certain trend, but this trend is reversed when the groups are combined. The paradox can be immediately understood using a simple example. We consider the two disjoint sets \(\#1\) […]
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The Google Tag Manager has become the de facto standard for integrating tracking scripts. This allows you to clearly separate responsibilities (online marketing vs. programming) and also allows you to quickly set up and modify tracking via another deployment channel. Here are two small tips for setting up triggers. When creating triggers, select […]
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As of FRITZ!OS 07.10, if the Internet fails, you have the option of temporarily having the FRITZ!Box use a cell phone's WLAN hotspot as a fallback. The function is hidden under Internet > Access data > Internet provider > existing WLAN access. The FRITZ!Box then works as a router itself and provides a network with its own address range. If the Internet is down […]
The post Quick Tip: FRITZ!Box WLAN hotspot first appeared on Vielhuber David .
The Flower of Life is a well-known, flower-like, geometric pattern that has been found in temples, manuscripts and, for some time, in pop culture for thousands of years. The pattern also plays a role in esotericism. We will ignore all of that at this point and concentrate on the […]
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The asynchronous communication medium email is - despite all the doom and gloom surrounding Slack and Discord - the dominant communication medium in the business world. In addition to Inbox Zero by Merlin Mann, there are numerous other strategies for dealing with the daily flood of emails, including so-called email delaying, i.e. the delayed delivery of emails. If you want to avoid [...]
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In the last few days I have been working on the following question on StackExchange about a spiral of integers. We are looking for a closed formula for the coordinates of the \(n\)-th element in the following integer spiral, which expands from the origin outwards to infinity: First we divide the natural numbers into the following […]
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When working with Google Sheets, you can set fine, user-based rules for editing worksheets, columns and rows within a spreadsheet. Unfortunately, there is no way to restrict reading rights. However, this would be very helpful in many scenarios. For example, you can only show your customers the tickets that concern them or show employees only the projects, [...]
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npm is the standard package manager for Node.js. Facebook has been developing an alternative package management solution called Yarn for some time now. Yarn seems to be slowly disappearing from the Github readmes as a standard solution and the stats on the official site show that only a fraction of the packages are implemented by Yarn. Nevertheless, it is worth looking beyond the box. […]
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The typesetting system \(\TeX\) was developed in 1977 by the legendary Donald E. Knuth. The software package \(\LaTeX\) is still part of the standard repertoire when creating scientific papers. With the following two tools, previously generated PDFs and handwritten notes can be converted fully automatically into TeX. The results are very promising. The first tool, Mathpix, is currently enjoying […]
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Nick Bostrom's simulation argument is strikingly simple and clearly formulated. It does not try to prove that we live in a simulation, but instead elegantly formulates three possibilities, one of which must be true. Elon Musk also supports a similar thesis, which has made the idea known to a wider public. The official paper is already […]
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The powerful plugins WPML for multilingualism and Advanced Custom Fields for your own fields are part of the basic equipment in many installations. It is annoying when the interaction leads to malfunctions and data loss. The bug reports on the topic are several years old and unanswered (here and here and here and here and here). I have […]
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On some Android phones, both the Facebook and Instagram in-app browsers (as of today) behave incorrectly if an upload field within an advertised or linked landing page had specified the accept attribute. This meant that the button was not functional. If you open the page in an external, normal browser outside of the Facebook app, everything is fine. This is annoying (especially since […]
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Google Chrome's developer tools are among the most powerful on the browser market. New features pour in every month, which Google presents in a compressed form on YouTube. But it is often the little things in life that bring joy. If you want to delete DOM elements in Google Chrome, you can do so with the Delete key. But only today did I notice that [...]
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A golden rule in the git universe is: "Do commit early and often". If you've had a long night or just want an overview of the current situation on your computer, the command d8a38f92d0baa14f9d4568826c13ad46 runs a "git status" for all repositories in the current folder or in any subfolder and accumulates [...]
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In the search for the optimal development environment, Windows 10 offers complete solutions such as XAMPP, WAMP and MAMP, a native installation by hand, and virtualization solutions such as Vagrant (Scotch Box) and Docker (Devilbox, Laradock). However, my requirements such as free configurability, real wildcard SSL certificates, access from all devices in the local network, and high stability and performance failed [...]
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One of Laravel's strengths is its elegant syntax. If you have a lot of models and relationships in Laravel (due to a lot of tables in the database), traversing can often result in less elegant code. Over time, three small extensions have proven useful for me, which I would like to briefly introduce below. To do this, I use […]
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Git version control is now standard in almost every web project and in every environment (including production). Git always creates the subfolder .git and if this is at the level of the website's public folder, sensitive files can be accessed publicly (for example, calling /.git/logs/HEAD shows the latest commits). [...]
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In an older blog post I described how to host Node.js for free using Heroku. Now I will show you a way to install Node.js, npm and Composer on any other shared host without root rights with just a few lines of code. This allows you to install packages, deploy Vue.js applications or simply create an Express.js […]
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In PHP <7.2 you can create arrays that you can no longer access properly: 91367d1c4636fd753b381406024e303c You can now do a few things with this. 91367d1c4636fd753b381406024e303c The root of all evil lies in bug #61655. As a workaround, you can turn the messed up array back into an object and cast it in a different way: 91367d1c4636fd753b381406024e303c Or you can just do without […]
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The following command connects to a server via SSH, executes some commands (for example, changes to a subdirectory and sets a git status) and leaves the shell open. The .bashrc file is loaded, which enables colored subshells. The trick is to create a temporary file /tmp/initfile with the desired commands […]
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If you map a network drive in Windows Explorer, this does not apply system-wide but only to the current user account. This means that you cannot access this network drive in an application that runs with administrator rights. This can be easily changed: In the registry under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System, create a new DWORD (32 bit) called EnableLinkedConnections with the value 1 [...]
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If you want to quickly access a local folder that you use again and again in Windows, you can simply assign it a separate drive letter. This is only possible via "Map network drive" in a roundabout way, since you cannot, for example, specify the path C:\Users\David\Downloads. The solution is to specify the so-called administrative share of the drive, which is available by default for every [...]
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A frog jumps around on the number line and you try to catch it. Jumping and catching alternate. The frog starts at position \(s \in \mathbb{Z}\) and on each move it jumps a distance of \(z \in \mathbb{Z}\) (if \(z>0\), it jumps to the right, otherwise to the left). \(z\) is on each […]
The post Catching Frogs appeared first on Vielhuber David .
Not only when using npm under Windows, you come across a limit that is now almost 30 years old, which limits paths to folders and files to a maximum of 255 characters. It is not NTFS that is to blame here, but LFN. This leads to annoying bugs and incompatibility between operating systems. In the age of WSL, this is a regrettable state of affairs that one has to […]
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In the PHP framework Laravel within productive environments, workers and supervisors ensure that the jobs stored in Redis, for example, are processed. If you want to be completely independent of this on localhost, you either use the sync driver to always execute the jobs immediately. This has the disadvantage that the current PHP process is blocked and the request hangs until the […]
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With the help of the JavaScript library analytics.js from Google Analytics, any event on a website can be tracked. These events include, for example, a precise measurement of the length of stay, the maximum scroll depth of visitors or other individual actions such as submitting forms. If you want to evaluate advertising campaigns later or carry out A/B tests, you create so-called goals. You can use the function […]
The post Quick Tip: Aggregate Goals in Google Analytics appeared first on Vielhuber David .
Server-side rendering is now part of the standard repertoire of websites and applications. Browsers such as Google Chrome also tend to cache as much as possible in order to minimize the loading times of subsequent calls. The cache invalidation of CSS/JS/image files can be done with the help of mod_pagespeed, Expires/Cache control header, a cache manifest or very pragmatically and directly by using individual parameters behind the file name [...]
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The provider Bitbucket does not offer (even in the paid tariffs Standard and Premium) the option of storing SSH keys with write permissions at the repository level. Storing your personal SSH key on the production server is not an option, as otherwise you would have access to all the other projects you are currently working on. There are so-called access keys, but these […]
The post Bitbucket and SSH keys first appeared on Vielhuber David .
The tools from Sysinternals by Mark Russinovich should not be missing on any Windows computer. If you always want to have the latest version to hand, you can mount it as a network drive. To do this, enter the command net use s: \\live.sysinternals.com\DavWWWRoot on the command line (as a normal user). Then you will have nice tools on drive S such as PsList, PsKill or the […]
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When outputting calendar weeks on a specific date, you have to be careful in Google Sheets (just like in Microsoft Excel). The function =CALENDARWEEK(TODAY()) calculates based on the American standard, for which the first day of the year is always assigned to calendar week 1. In Germany, this is defined differently: Here, the first calendar week is the week […]
The post Quick Tip: Google Sheets and Calendar Weeks appeared first on Vielhuber David .
Since Let's Encrypt, encrypted websites have become standard nowadays. SSL certificates are also indispensable for local development (for example, navigator.geolocation requires SSL encryption locally as well). Since version 58 of Chrome, support for CN (Common Name) has been abandoned and SAN (Subject Alternative Name) has been made mandatory. This means that Chrome accepts all […]
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Consider two people \(A\) and \(B\) who do not have the same birthday and \(A\) is younger than \(B\). Show that there are exactly two age constellations \(a,b \in \mathbb{N}\) for which \(2\cdot a = b\ applies. First, we set \(d \in \mathbb{R}^+\) as the age difference between \(A\) and \(B\) at the birth of \(A\) […]
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Since Git does not know folders, only files, empty folder structures do not end up in the repository. However, since many frameworks and projects absolutely require them, they should end up there. A common practice is to create so-called placeholder files (often called .gitkeep) that implicitly specify the folder structure. These files can be easily created and, if desired, additionally [...]
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Hosting for Node.js is still not very common, especially in German-speaking countries. The American cloud company Heroku offers a solution here - and it's even free. You always notice the paradigm "Build apps... not infrastructure" and yet there are hardly any restrictions. As an example, we are implementing a small cron job based on PhantomJS that scrapes a website every day and […]
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In addition to the diagonal arguments, Georg Cantor also developed the Cantor pairing function \(\mathbb{N}^2 \to \mathbb{W}, \quad c(x,y) = \binom{x+y+1}{2}+x = z\), which encodes any two numbers \(x,y \in \mathbb{N}\) in a new number \(z \in \mathbb{N}\). For example, \(c(3,4)=\binom{3+4+1}{2}+3 = \binom{8}{2}+3=\frac{8!}{6!\cdot 2!} +3 = 31 = z\) is a unique encoding of the numbers \(3\) and \(4\) […]
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Consider the earth (as a sphere with \(r_1 = 6370km\)) and a pea (as a sphere with \(r_2 = 2mm\)) and stretch a rope over the equator so that it lies taut on the surface. Now extend both ropes by one meter each. Both ropes should now be completely stretched out again over the equator – […]
The post The Earth and the Pea first appeared on Vielhuber David .
In what percentage of the time in a day are all three hands of an analogue clock on the right half of the clock face? First, look at the hour hand, which is on the right side for 12 out of 24 hours (50%). Of this time, the minute hand is on the right side for 6 out of 12 hours […]
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Laravel makes communication with the database much easier with Eloquent. When working with Eloquent Relationships, you should be aware that when calling dynamic variables (using PHP's magic methods), the instances of the models do not reflect new changes, but rather permanently cache them when they are called for the first time. The following example is […]
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When hosting Git on Bitbucket, there is a hard limit of 2 GB - if this is exceeded, you only have read-only access to the repository. To prevent this, you can, for example, retroactively remove large folders or files from your commits. But even in other cases (if access data has been included in the history or once again [...]
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In the age of Let's Encrypt, encrypted websites are now the norm. But wildcard or extended certificates with particularly trustworthy owner validation are also often required. The provider DomainFactory offers inexpensive SSL certificates that can also be used externally. Setting up on a current IIS is possible without CSR using OpenSSL. Below I will briefly show you the steps involved […]
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In 1987, Thomas M. Cover asked the following astonishing question in "Open Problems in Communication and Computation": Player \(X\) writes two different and randomly chosen natural numbers \(A\) and \(B\) on two different pieces of paper and places them face down on a table. Player \(Y\) then randomly selects one of these pieces of paper, sees the number and must now […]
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When a football match kicks off, the ball is in the middle of the field and is then moved around the field for 45 minutes by shifting and rotating. At the start of the second half, the ball is again in the middle of the field. We show using simple linear algebra that there are then either infinitely many points […]
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When debugging blade templates in Laravel 5.*, you often get meaningless error messages that refer to cached views. But everything used to be better: The debugging view in version 4 contained more helpful functions and was also visually more attractive. With a few lines of code, you can get this functionality back with the help of whoops ("PHP errors for cool kids"). [...]
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Whether references, partners or customers - there are many cases in which you want to display several logos next to each other harmoniously. The proportions of the logos are usually not uniform. Often, when it comes to the size representation in the design, you follow your gut feeling, but there is also an exact method of calculating a visually appealing representation by equating the areas of the logos. In […]
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When working with variables in PHP and JavaScript on a daily basis, you often come across the query as to whether a variable is empty. It is worth knowing the native functions and their differences for checking. Unfortunately, there is no simple method to check in an intuitive sense whether a variable exists or not. What this means […]
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With sipgate.io, Sipgate has created an exciting cloud API that offers a wide range of options for Internet telephony. An account is free, and the feature store also offers the option of setting any free sender number for free. The documentation for sipgate.io still needs to be improved, but with a little reading of the official Sipgate API, you can […]
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Relational database management systems based on SQL are only partially suitable for hierarchical or recursive queries. Other systems such as ArangoDB are better here (there was a great talk about this at GOTO 2016). However, you can also create recursive queries in SQL using Common Table Expressions and, for example, search classic parent/child tables for all ancestors and descendants […]
The post Recursion in SQL appeared first on Vielhuber David .
According to w3techs.com, around 27.4% of all websites worldwide are currently operated using WordPress. In many cases, these are not blogs. WordPress automatically generates numerous, often unused URLs and produces so many links indexed by Google that the website operator had never even considered. All of this can be done with a simple command [...]
The post WordPress: Disable archive pages appeared first on Vielhuber David .
If, like me, you find yourself in the predicament of having to rename thousands of form field names, the JavaScript console included in Acrobat is a good option. In this console, you can not only execute any JavaScript code, but also access all content within the PDF (including form fields). Since there is no native function for renaming in the JS API, the form fields are renamed with all […]
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A known problem has still not been resolved in Shopware 5: If you create an article with dependent variants with mutually exclusive configuration options, it can happen that some combinations cannot be selected in the frontend and therefore cannot be ordered. The problem can currently be easily resolved with the help of a plugin. The following simple example illustrates […]
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There are numerous proofs of the infinity of prime numbers - Euclid's famous theorem from the Book of Elements is included in every introductory lecture on number theory. In 2015, Sam Northshield published an equally elegant proof by contradiction in the form of a one-liner in the American Mathematical Monthly (issue 122), which I would like to share with you (with brief comments). $$0 < \prod_{p} \sin \underbrace{ \left( \frac{\pi}{p} […]
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$$\int_{-\infty}^{\infty} e^{-x^2} dx = \sqrt{\pi}$$
The post A Little Equation #15 appeared first on Vielhuber David .
The boring Windows command prompt can be visually enhanced in just a few steps. Not only can you change the color and size of the command line, but you can also expand its functionality (increase the buffer, install a large set of UNIX tools). Although the command prompt does not come close to PowerShell 6.0 or the new Windows 10 Bash [...]
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In content management systems, URLs are often not always fixed in advance and are therefore not created statically (as a post or menu item) but rather address objects from the database. Similar to WordPress (as described here), it is also possible to set up dynamic URL structures in Joomla (independent of the internal alias system). Either JRouter is a good option for this – or you can […]
The post Dynamic URLs in Joomla appeared first on Vielhuber David .
Modern browsers can use JavaScript to access the user's clipboard for both reading and writing, and thus also manipulate it. The underlying technology is already old hat, but only recently have more and more attacks (under the name "PasteJacking") been circulating on the Internet that use this option to the detriment of the unsuspecting user [...]
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Swapping SQL table columns is part of the standard repertoire in MySQL – this is not (yet) supported in PostgreSQL. Although the official wiki has dedicated a separate post to the problem, it does not show a practical solution that also supports views, indexes and triggers. The following class does this job (for both MySQL and PostgreSQL) either on the command line – […]
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If you want to quickly open the command prompt in a folder in Windows Explorer, click on the folder (one level up) with the right mouse button and hold down the Shift key and then select "Open command prompt here" from the context menu. I have just discovered another, faster method when you are inside the folder: Here you click in the current [...]
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If you work with hierarchical categories (taxonomies) in WordPress, you will notice that, on the one hand, the display of the checked categories in the backend is confusing and, on the other hand, posts do not automatically end up in the parent category when they are placed in the child category. Both can be achieved with just a few lines of code using the powerful hook system (in the form of an action and […]
The post WordPress Categories: Tree View/Inheritance appeared first on Vielhuber David .
In addition to new features such as type hinting for scalar data types or optimized performance, PHP 7 also brings with it many new, useful language extensions. The "Spaceship Operator" has finally made it into the world of PHP (Ruby and Perl programmers have known it for a long time). \($a <=> $b\) returns \(0\) if and only if both operands are equal […]
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If you integrate PHP via FastCGI on IIS 7.5, every script is aborted after 600 seconds (i.e. 10 minutes) by default. Changing the well-known variable "max_execution_time" in the php.ini has no effect on this, you must (also) adjust the FastCGI settings. IIS offers a convenient interface for managing the relevant variables. To do this, open […]
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Conditional probability theory brings with it nice problems with counterintuitive solutions. In addition to the well-known sibling problem, I would now like to briefly discuss another example: "I now have two children. One of them is a boy and was born on a Thursday. What is the probability that the other child is also a boy?" We choose the result space $$I = \{(J.MO,J.MO), (J.MO,J.DI), (J.MO,J.MI), […]
The post Paradox of Stochastics first appeared on Vielhuber David .
The file version management system Git is slim, fast and portable. Git always deals with objects, namely files. Folders are only created if they contain files, otherwise Git does not record them at all. This has unpleasant side effects in some projects. For example, the Shopware shop system relies on strict adherence to the folder structure in order to function. If even one […]
The post Git, Shopware and empty folders first appeared on Vielhuber David .
Shopware has a powerful shipping costs module, which you can use to make very specific adjustments to the calculation. In our case, we want to implement the following scenario: The shipping costs per item are initially determined based on the weight of the item (the weight limits are specified). Only for special exceptions should fixed shipping costs be individually set for each item. The shipping costs table looks like this […]
The post Shopware: Individual shipping costs first appeared on Vielhuber David .
It is already almost impossible to avoid it if you want to work flexibly and independently: the cloud. There are probably a lot of people who already use the cloud without knowing it. With streaming, for example, all the content is stored in the cloud and can be accessed when needed. Netflix is one example here, […]
The post Bring your own device appeared first on Vielhuber David .
The WordPress permalink system can be adapted to your own needs very well with the help of structure tags. The %postname% setting is probably the most common and practical solution. However, if you want to implement real dynamic links, you first have to extend the system with your own code. The powerful WordPress Rewrite API offers many options for adapting the system to your exact […]
The post Dynamic Permalinks in WordPress appeared first on Vielhuber David .
You would think that when you open hyperlinks from a Word/Excel document, the default browser would be started with the desired URL. Strangely enough, this is not the case - which leads to unpleasant side effects and makes links for session/cookie-based login-protected pages in the Office programs mentioned impossible. The culprit is the module named by Microsoft called "User Agent: Microsoft Office [...]
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For today's Father's Day, a daughter gives her father a self-painted picture that the father had wanted from her for a long time. The daughter says: "I'm giving you the picture that you wanted, and my gift will be a surprise." The father is taken aback and considers the truth of this statement. The statements "I'm giving you the [...]
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If you include unencrypted scripts in the <head> area and call up a page with an existing SSL certificate in encrypted form, these scripts are blocked and therefore not executed. If you simply leave out the protocol, all scripts are automatically called up in encrypted form if the website is accessed via https:// - otherwise unencrypted. To do this, simply use [...] instead of <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.2/jquery.min.js"></script>
The article Dynamically embedding scripts with and without HTTPS first appeared on Vielhuber David .
When working with multidimensional dropdown menus, you often encounter the problem that the wrong submenus are accidentally opened or the desired submenu is accidentally closed. This effect occurs when the mouse pointer leaves the corresponding menu at the upper level when navigating to a submenu that has already been expanded. To solve the problem, you can use […]
The post Usability in dropdown menus appeared first on Vielhuber David .
In Shopware, the entire article is deactivated for a real order if all variants have a stock level of less than or equal to 0. In order to implement this on a variant basis, I have programmed a small plugin, the Bootstrap.php of which I am making available below. 8f3757318524b4883325 The plugin can also be found free of charge in the Community Store: Variants […]
The post Shopware: Automatically deactivate variants first appeared on Vielhuber David .
The following situation always results in an unpleasant side effect: If you protect your site with htaccess/htpasswd and at the same time force an SSL connection, you always have to enter the same password twice (once for http and once again for https after successfully entering it). The problem can be easily dealt with using the configuration sections introduced in Apache 2.4. […]
The post Double password request with SSL first appeared on Vielhuber David .
When programming with JavaScript, you often stumble upon the lack of the possibility to create multi-line strings by entering them in multiple lines in the code. While this task is not a problem in other languages such as PHP or Ruby, in JavaScript you can only use workarounds, the use of which depends on personal taste or […]
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For several years now, they have been popping up everywhere: online casinos. Countless providers allow gambling fans to indulge in their favorite pastime around the clock on the Internet. Those who used to enjoy going to the casino can now save themselves the trip and simply turn on their computer. But how exactly does this principle work […]
The post The Technology Behind Online Casinos appeared first on Vielhuber David .
Sending emails with PHP is best done with powerful classes like PHPMailer. Convenient wrapper functions make it possible to use content in UTF-8, embed images and send encrypted attachments with just a few lines of code. If you want to save yourself the overhead and use the PHP function mail() contrary to the recommendation, you will come across problems when using umlauts […]
The post mail() in PHP with UTF-8 and umlauts first appeared on Vielhuber David .
Validation tools such as the W3C Markup Validation Service or Google PageSpeed Insights are helpful for objectively evaluating the code and performance of a website. Google in particular influences an entire industry with concepts such as above the fold - and also provides strict but useful guidelines when it comes to image compression and caching. However, it can happen that Google itself [...]
The post Google PageSpeed Insights vs. Google Analytics appeared first on Vielhuber David .
$$\sqrt[3]{-1} = \fracVielhuber{2} + \frac{\sqrt{3}}{2}i$$
The post A Little Equation #14 appeared first on Vielhuber David .
JavaScript dominates the web - and ECMAScript, the core of the language, is coming of age. The new specification (ES6 or JS2), which is expected in the middle of this year, brings with it numerous innovations that you can try out today. Firefox currently has the best support, but polyfills through so-called transpilers such as Google Traceur are also possible. It [...]
The post Welcome JavaScript 2.0 appeared first on Vielhuber David .
Whether at school or university: An interesting question that comes up every now and then involves the question of whether the following equation is true: \( 0.99999... = 1 \). Although infinity lies dormant in the left-hand part of the equation, we give it a name: \(0.99999... = A\). After multiplication by the factor \(10\) and simple algebraic […]
The post 0.99999... = 1? appeared first on Vielhuber David .
I was just confronted with the following performance problem in an SQL database: In an SQL table called "users" with ~1,000,000 entries, determining the number of registrations on the current day took an unbearable 28 seconds. The times of the registrations were stored in the "created" column in the format "Ymd H:i:s". The query used was SELECT COUNT(ID) FROM users WHERE DATE(created) = '2014-12-21'; [...]
The post SQL: Poor performance despite index appeared first on Vielhuber David .
In addition to the well-known knight problem and queen problem, there are many other exciting questions in the world of chess. I touched on two small curiosities in a previous blog entry. If you deal with chess problems mathematically, you quickly realize that mathematics provides very simple and enlightening answers to many questions. I will now deal with the following problem as an example: You […]
The post Small Chess Problem first appeared on Vielhuber David .
$$\frac{d}{dx}(e^x) = e^x$$
The post A Little Equation #13 appeared first on Vielhuber David .
Whether OneDrive, Dropbox, Google Drive, OwnCloud, Box.net: No matter which box you use to store your files, the services are almost identical. The clients available for all desktop and mobile systems, the files that are unencrypted by default and the sharing options only differ marginally. But OneDrive, which has been integrated into the system since Windows 8.1, has a special feature […]
The post Files available online with OneDrive appeared first on Vielhuber David .
Files on web servers should always be stored without spaces (not "this is a picture.jpg"), without umlauts or special characters (not "football.jpg"), without backslashes (not "work\car.jpg") and in lowercase (not "test.JPG"). Recently, however, I had to access a large number of predefined files with arbitrary file names for a customer project and process them further. Linux systems allow access to files by default […]
The post PHP: File access with umlauts under Windows first appeared on Vielhuber David .
$$e^{i\pi} + 2 = 1$$
The post A Little Equation #12 appeared first on Vielhuber David .
Today, while working on a customer project, I came across the following task: Take an SQL table "user" with the columns "id" and "score" and determine a ranking list of all users sorted by "score", in which users with the same score get the same ranking. By using user-defined variables, this task can be done intuitively and easily [...]
The post SQL query to determine a ranking list first appeared on Vielhuber David .
When working with the Facebook SDK (more precisely when implementing a Facebook login function within a REST interface), the transmitted token that the client has received from Facebook must first be checked for validity by the server before further operations are carried out. The easiest way to do this is with the undocumented API call GET https://graph.facebook.com/me?access_token=TOKEN where TOKEN is the 200-character […]
The post Facebook SDK: Verify tokens server-side appeared first on Vielhuber David .
Whether Chrome, Firefox, Opera, Safari or even Internet Explorer: Until a few years ago, sophisticated developer tools were a unique selling point of Firefox and the popular Firebug plugin. Today, powerful developer tools are part of the standard scope of every browser, and there is a lot to discover. I have just come across a trick to […]
The post Chrome DevTools: Addressing DOM elements appeared first on Vielhuber David .
$$1 + \fracVielhuber{2} + \fracVielhuber{4} + \cdots = 2$$
The post A Little Equation #11 appeared first on Vielhuber David .
I have just come across a nice way in MySQL to tap into the file system and obtain valuable information, for example about the existence of files and folders or their contents. This can be very useful as an alternative to the PHP function file_exists, since the information about the existence of the file(s) is still in the query for further sorting and [...]
The post Accessing the file system using SQL appeared first on Vielhuber David .
$$\int_{0}^{\infty} e^{-x^2} \, dx = \frac{\sqrt{\pi}}{2}$$
The post A Little Equation #10 appeared first on Vielhuber David .
Animated vector backgrounds can bring variety to a web landscape dominated by full-screen photos and videos. It would be nice if this was accompanied by shorter loading times and broad support for hardware and software. One solution is: Canvas. The HTML element controlled by JavaScript is supported by all current browsers and is displayed efficiently on mobile devices. The real strength lies in the fact that the […]
The post Animated Backgrounds with Canvas appeared first on Vielhuber David .
As a web developer, you often find yourself in the embarrassing situation of working with HTML elements that do not have a fixed size or aspect ratio - unlike the img element, for example. Often you want these objects to behave responsively, but the proportion between width and height is maintained. CSS does not offer any standard […]
The post Fixed aspect ratio for HTML elements first appeared on Vielhuber David .
$$\fracVielhuber{89} = 0.011235955 \ldots$$
The post A Little Equation #9 appeared first on Vielhuber David .
After the Cologne Regional Court backtracked on the RedTube scandal last week and ruled that it should never have approved the release of the disputed IP addresses, it has now issued another highly controversial and questionable ruling in its decision 14 O 427/13: The author of stock photos from a certain photo agency must also be named when his images are accessed directly via their URL […]
The post Court ruling on the use of stock photos first appeared on Vielhuber David .
There are many new features in the HTML5 specification and many of them are already supported by the majority of browsers – below I want to highlight an interesting change to the rules for nesting elements. HTML has always distinguished between block and inline elements. For example, the Document Type Definition of HTML4 lists h1, p, and div as block elements and a, […]
The post Goodbye Block & Inline - Welcome HTML5 appeared first on Vielhuber David .
Both Apache on Unix and IIS on Windows systems log HTTP requests out-of-the-box in file format. Requests to your own website should be regularly evaluated and analyzed manually and automatically (e.g. using log file analyzers such as AWStats), not only to protect against hacking attacks. The paths of the relevant log files in widely used configurations are as follows: /var/log/apache2/access.log (example: Ubuntu 12.04, […]
The post HTTP Logging on IIS and Apache appeared first on Vielhuber David .
$$\sqrt{-1} \times \sqrt{-1} = -1$$
The post A Little Equation #8 appeared first on Vielhuber David .
When integrating Joomla 3.2 on a Windows Server 2008 R2 with IIS 7.5, problems with directory rights often arise, which are often inadequately solved with settings that are chosen far too generously. The following solution is safe and fully functional: The IIS_IUSRS group needs the following rights for C:\inetpub\wwwroot\: Read & Execute, Display folder contents, Read, Write […]
The post Joomla, IIS and directory permissions first appeared on Vielhuber David .
In times of the NSA scandal, it is not only internet-savvy users who are asking themselves whether and how they can move anonymously on the Internet in order to avoid the authorities and secret services' mania for collecting data. However, this often leads to errors and false assumptions. A central misconception is that anonymity is reduced to concealing the IP address. It [...]
The post Anonymous on the Internet: Impossible? first appeared on Vielhuber David .
$$\frac{6}{3} + \sqrt{4} = 2 + 2$$
The post A Little Equation #7 appeared first on Vielhuber David .
The discount fitness chain McFIT is giving itself a new look. Whereas a bright yellow mascot in the shape of a banana used to adorn the blue lettering, a yellow bow now skilfully intertwines on an anthracite background, forming an abstract structure. The FDP colors blue and yellow are not only used on the logo, but also on all […]
The post McFIT - New logo, new image first appeared on Vielhuber David .
$$\fracVielhuber{\sqrt{2}} + \fracVielhuber{\sqrt{2}} = 1$$
The post A Little Equation #6 appeared first on Vielhuber David .
When the brothers Thomas and John Knoll started developing Adobe Photoshop in 1987, I was not yet born. Today, in 2013, the software is one of the most popular programs in general and the undisputed market leader in the image editing field. Thanks to Adobe and the Computer History Museum, the software is now being preserved for posterity throughout […]
The post Photoshop: Journey into the Past appeared first on Vielhuber David .
Chess has fascinated people for centuries - its rules are easy to learn and its incredible depth is only accessible to experienced players (of which I am unfortunately not one). Below I will deal with two entertaining questions: Is it possible to reach a position through a correct sequence of moves in which the black king is attacked by two white queens at the same time [...]
The post Curiosities in the Game of Kings first appeared on Vielhuber David .
$$\fracVielhuber{89} = 0.\overline{011235955}$$
The post A Little Equation #5 appeared first on Vielhuber David .
Cinema films are usually recorded and played back at 24 frames per second - but the almost 100-year-old standard format "24p" seems to be shaky. In order to prevent the unpleasant side effects (e.g. the strong jerking during medium-fast camera pans) of 24fps projection, work has been underway for some time to double the frame rate to 48 frames per second [...]
The post Documentary soap instead of blockbuster: 48fps first appeared on Vielhuber David .
$$\frac{d}{dx}e^{x^2} = 2xe^{x^2}$$
The post A Little Equation #4 appeared first on Vielhuber David .
Automated spelling and grammar checking is now standard in word processing programs - but automatically checking the spelling of a website has so far been relatively cumbersome. Google Chrome is taking a first step in this direction with an integrated check in multi-line input fields (textarea). Now there is a service that makes this possible for entire websites. The service […]
The post Spell checking on websites first appeared on Vielhuber David .
A few weeks ago I reported on how you can enable your visitors to open the phone app on mobile devices by tapping on a phone number. Now a way has emerged to use such links to irreversibly block the SIM card or reset the device to factory settings without the user having to do anything. Special links that are lurking almost everywhere and also […]
The post Telephone numbers in links - a security risk? first appeared on Vielhuber David .
$$\int_{-\infty}^{\infty} e^{-x^2} \, dx = \sqrt{\pi}$$
The post A Little Equation #3 appeared first on Vielhuber David .
Should domain names and email addresses always be written in lowercase to ensure that you get to where you want to go? Or is this completely irrelevant? Google's mail servers, for example, have strange settings with interesting effects, which I will briefly introduce in the following article. Google, which has recently also offered @gmail.com addresses to German users, ignores dots before the […]
The post Interesting Email Curiosities appeared first on Vielhuber David .
$$\sqrt{-1} = i \quad \text{and} \quad i^2 = -1$$
The post A Little Equation #2 appeared first on Vielhuber David .
I follow the design of various programs on German television closely. Hardly any program keeps its corporate design permanently. The nightly ritual of gathering in front of the television screen at 10:15 p.m. to watch the latest news has been giving me a stomach ache lately: For several months now, a completely confusing color scheme has been used when presenting the current stock prices [...]
The article Design of stock prices in the Tagesthemen first appeared on Vielhuber David .
$$e^{i\pi} + 1 = 0$$
The post A Little Equation #1 appeared first on Vielhuber David .
If you optimize your own website for mobile devices, you should not only pay attention to different screen sizes, optimized loading times and special features in operation (such as hover effects), but also consider the special capabilities of the devices. This includes (some people may have forgotten) making phone calls. A "+49" in front of the href attribute is recommended, by the way, because it [...]
The post How to link phone numbers correctly appeared first on Vielhuber David .
The same content on different websites is often penalized by Google - but the Google algorithm is intelligent and recognizes whether the elements in the header and footer are the same or whether entire test passages are accessible twice under different URLs. It is interesting to see how Google deals with blog article overview pages. The YouTube channel Google Webmaster Help provides [...]
The post Duplicate Content on Blogs first appeared on Vielhuber David .
The security of the currently most popular content management system, WordPress, can be significantly increased by turning two small adjustment screws. This only takes 5 minutes and two lines of code. Although the problem can also be solved with a variety of plugins, I am deliberately limiting myself here to plugin-free solutions. On the one hand, the meta tag <meta [...]
The post Increase WordPress Security appeared first on Vielhuber David .