Practical Linux Command Line Tips for Productivity and Efficiency
By Edgar Mlowe
June 22, 2024
Feeling stuck with basic Linux commands? You’re not alone! Many people know some commands but don’t feel efficient. The good news is that with some know-how and common commands, you can transform your skills.
In this post, you’ll learn to combine commands with pipes, master shell techniques, efficiently recall and edit past commands, and navigate the filesystem with speed. Let’s dive in!
1. Combining Commands with Pipes
Understanding How Pipes Work
Ever wish your commands could work together? Pipes make it happen! They let one command pass its output to another, creating a smooth workflow.
Commands take input (stdin) and give output (stdout). The pipe symbol (|) links them, making life easier.
For example, ls -l /bin lists files in the /bin directory, but the amount of output is overwhelming. Try ls -l /bin | less to view one screen at a time—like having a personal organizer! This command pipes the output of the ls command into the pager less, which is very useful for reading large amounts of data.
Let’s dive into pipes and practice them with commands like wc, head, cut, grep, sort, and uniq to handle data like a pro. If any of these commands are new to …
linux shell tips
Docker and iptables
By Jeffry Johar
June 12, 2024
Photo by Egor Kamelev from Pexels.
Docker utilizes iptables for its networking and routing. Blocking and accepting connections to the running containers on a host might be tricky at first if we are not aware of where Docker puts its chains. Docker chains are all located in the iptables FORWARD chain. Within this chain, Docker provides a convenient chain named DOCKER-USER for users to add their custom rules.
One common mistake is attempting to block Docker Containers at the iptables INPUT chain, which will not work. This is because Docker does not pass through the INPUT chain, it only passes through the FORWARD chain. The following diagram illustrates a simplified chains traversal of Docker containers.
Below are a few working examples of iptables rules that can serve as references. These rules will be applied to the DOCKER-USER chain. It’s important to note that the DOCKER-USER chain comes after the PREROUTING chain and FORWARD chain, so we’ll need to use the iptables conntrack module for getting the information about source addresses and host ports. iptables conntrack extension allows iptables to track the state of network connections passing through the system. This …
docker linux iptables redhat
End Point’s CasePointer business acquired by Deloitte
By Rick Peltzman
June 3, 2024
We are proud to announce that Deloitte has acquired the industry-leading public health disease surveillance business, CasePointer, from End Point Corporation as of June 1, 2024. This acquisition brings to Deloitte, End Point’s experienced and skilled software engineers, cloud developers, DevOps engineers, epidemiologists, and former public health officials.
Since 2008, End Point’s CasePointer business has worked with open-source public health software to modernize tools, automate processes, improve the user experience, and provide better return on investment to state and local public health agencies for their disease surveillance and epidemiologic needs.
Jon Jensen, End Point’s former chief technical officer, has joined Deloitte with this transaction. He said: “We are excited to work with Deloitte’s team of professionals and serve their broad client base. Together, we expect to make an even greater impact for government health organizations.”
Deloitte is only acquiring assets, clients, and personnel related to End Point’s CasePointer business. All other business lines remain with End Point, including systems administration, database engineering, e-commerce programming, application …
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How to validate record uniqueness in ASP.NET
By Kevin Campusano
May 28, 2024
In ASP.NET, the System.ComponentModel.DataAnnotations namespace includes many attributes that can be used to instruct the framework to perform basic validation tasks for us. There are built-in validators for ensuring that certain fields are present, that they meet character length limits, that they don’t exceed or fall short of certain amounts, that they match certain formats, and more.
One omission however, is checking for record uniqueness: making sure that no other record in the entity’s underlying persistent data storage has the same “name”, or the same “code”, or the same “any other field”.
In this article, we’re going to try to address this shortcoming by implementing this type of uniqueness validation ourselves. We will see two approaches: a simpler solution using a database index, and a more flexible one using a custom validation attribute. Let’s get started.
Throughout this article, I will be using a demo Web API application for code examples. If you’d like to see what the final implementation looks like, you can find all the code on GitHub.
The API is about calculating quotes for used vehicles based on …
dotnet aspdotnet csharp
Writing integration tests for an ASP.NET Web API
By Kevin Campusano
May 13, 2024
Integration tests exercise a system by instantiating major components and making them interact with each other. They are great for validating important use case scenarios in an end-to-end or close to end-to-end manner.
Full integration tests seldom use mocks or fake objects. Usually, the full stack is tested as if the entire system were running for real. For REST APIs, that generally means tests that involve issuing HTTP requests, validating HTTP responses, and asserting on changes made to a persistent data store, like a database.
In this article, we’re going to discuss how to write such tests for a Web API built using ASP.NET.
Introducing the project
I’ll use an existing ASP.NET Web API project to demonstrate how to write these tests. The API is part of a system that calculates the value of used cars and offers quotes for them. As such, the API has an endpoint for calculating a vehicle quote, given its information and condition: POST /api/Quotes. It also has an endpoint for administration purposes that returns all the quotes that have been stored in the system’s database: GET /api/Quotes. These are the two endpoints that we’ll want to test.
The source …
testing dotnet aspdotnet csharp rest api
An OpenStreetMap Editor for Adding Public Transit Data Using GTFS
By Dmitry Kiselev
May 8, 2024
You can think of OpenStreetMap (OSM) as Wikipedia for maps. While it may not be as well known as Google Maps or Apple Maps, OSM becomes indispensable when you need data, rather than just a visual representation on your phone. The only other real option for data retrieval is to consult a local agency, so if you’re in search of a comprehensive and global cartographic dataset, OSM is the go-to choice.
OSM also excels in providing navigation for pedestrians and cyclists. For the past decade, I’ve navigated the US, Canada, and Europe using OSM through the OsmAnd app, a dedicated Android application for OpenStreetMap.
Overall, my experience has been quite positive, except for one significant weakness: public transportation. Specifically, I’ve been missing the convenient access to timetables for buses, trams, or any other form of public transit.
A significant part of the challenge in making public transportation data readily available on OSM and its associated applications is the fact that the OSM data model isn’t particularly well suited for this type of information. While OSM can store the location of bus and train stops, the actual timetables change so often that …
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Using Razor templates to render HTML emails in .NET
By Kevin Campusano
April 30, 2024
When it comes to sending emails, Ruby on Rails has an excellent solution in the form of Action Mailer.
The basic idea is that you can define email templates using ERB files. This is the same templating engine/language used for normal web application views. Then, application-level SMTP settings are configured for email delivery. Finally, a “Mailer” class can be developed that leverages the templates and the underlying email sending mechanism to send emails.
In Rails, all this comes right out the box. Setup is minimal, so this approach is a huge time saver for a task that’s very common in web applications.
In ASP.NET Core (or .NET in general), we don’t have such a convenient, built-in solution. However, it is possible to implement our own using the framework’s features.
In this article, I’m going to explain step by step what I did in a recent .NET project to develop functionality similar to what Action Mailer provides.
Throughout this article, I will be using a demo Web API application for code examples. If you’d like to see what the final implementation looks like, you can find all the code on GitHub. The API is about calculating quotes …
email dotnet csharp
Passing Data Between Components in Vue.js: An Overview
By Tuğrul Gökbel
April 3, 2024
Artwork: Still Life with Artichokes and a Parrot, 17th century, Italian. CC0.
Vue.js, with its simplicity and flexibility, is one of the most popular JavaScript frameworks on the web. One of the key aspects of building dynamic and interactive web applications with Vue is efficiently passing data between components. In this blog post, we will explore methods and good practices for data communication between Vue components.
Props
Usage
Directional data flow: Props are primarily used for establishing a unidirectional flow of data from parent components to child components — they allow parents to pass data down to their children.
Pros:
Simplicity: Props provide a simple and straightforward mechanism for passing data.
Cons:
One-Way Binding: It’s a one-way data binding mechanism, meaning that data flows from parent to child only, not from child to parent.
// ParentComponent.vue
<template>
<ChildComponent :data-prop="parentData" />
</template>
<script>
export default {
data() {
return {
parentData: "Hello from parent!",
};
},
};
</script>
// ChildComponent.vue
<template>
<div>{{ dataProp }}</div> …vue javascript programming