This is probably more suited to be a Stack Overflow answer, but I figured the answer is so interesting, I’d write a Medium post about it.

First of all, let’s define the problem:

Until this day, developers that wanted to create an SSH tunnel for development purposes only had to spin up another terminal and run an SSH command with a forward tunnel command, e.g.

ssh -N -L 3306:mysqlserver.internal:3306 user@bastion.com

They would then configure their development environment to connect to localhost:3306 for their MySQL server, instead of connecting directly to the unexposed mysqlserver.internal.

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Tunneling without Docker

In 2020, you are likely using Docker…


As much as Spark and Python are great at data analysis, most of the time, as a data engineer, you just want to start working on your CSV file in the command line.

Well, as it turns out, there’s so much you can do just with Bash. And it’s SUPER fast and easy.

The data set we’ll be using is some random sales database I found online here:

http://eforexcel.com/wp/downloads-18-sample-csv-files-data-sets-for-testing-sales/

If you start by looking at the file, you get something like this:

cat sales.csv | less -S
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As it turns out, there’s this cool tool called column which makes your…


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WeWork has worked hard to position itself as a fast-growing tech company with a bright future. SoftBank agreed to invest in the company at a $47 billion dollar valuation. But is it really worth that much?

Let’s take a balanced view on how much WeWork is worth, looking at the company from a few different perspectives: the “monopoly factor”, the business model, and the strength of the brand.

The “Monopoly” factor

In Peter Thiel’s book “Zero to One”, Peter speaks about companies being monopolies as a good thing. When monopolies encounter the simple consumer, it can cause unjust harm. But when monopolies encounter…


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Over the years, working with start-ups and investors (as well as starting a few and selling one) taught me how to understand the value of the special breed of companies called “start-ups”. Today, after giving my pitch to a friend (Noam Bernstein) he mentioned I should write a Medium post about it, so I guess that’s what I’m doing now.

Start-ups are very different than normal companies in many ways. You can define them in many different ways and they probably all make sense, just as modeling a photon can be done by a wave function and a particle model…


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APIs are ubiquitous. You can do just about everything you want with APIs today, which is pretty awesome, and solve any problem that used to require technology that only a few people had. I decided to solve an annoying problem I had every morning when I drive to work: I want someone to summarize the front page of Hacker News while I drive.

The thought of generating speech using a computer always was a terrible idea because it hurts my ears to listen to. However, as it turns out, Google’s newly released Wavenet-based Text-to-Speech technology is good enough to listen…


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I’m not a biologist. But I do know a few things about aging. And I did come to an interesting conclusion that may actually make you want to upload your DNA to your favorite cloud storage.

Cells replicate naturally. As they replicate, two things happen: the DNA is copied, and the size of the telomeres decreases. As the cell telomeres size reaches zero, the cell stops replicating and dies. One of the reasons cells stop replicating is because the DNA copy process has errors. Why? …


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Apache Pig is one of my favorite programming languages. Pig is a “data flow” language — kind of a hybrid between SQL and a procedural language. It mostly resembles bash one-liners that pipe data in and out.

Pig is not being used anymore, because it was replaced by different tools and different approaches (stream processing for example).

For ETL batch workloads, it was mainly replaced by Spark, which is superior in almost any way. For the ones who like SQL-like processing there’s Spark SQL, and for those who like to code there’s Scala Spark and PySpark.

For BI workloads, languages…


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Writing your own version of a server is always a good exercise. The interface is very well defined, clients exist everyone, and it proves you can master a programming language to write practical applications.

Memcached is a practical application which is extremely easy to implement from the ground up, and it’s what we’ll use for our example.

Step 1: Figuring out how to build a web server

In every programming language, this usually ends up with a copy-paste of something. Let’s do the same with Python! Apparently, Python 3 now has a cool new feature called socketserver which we will use. …


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Disclaimer: I am not responsible for anything you do with this information.

This post was originally published in 2017.

As I entered the parking lot, I took out my parking ticket and put a sticker on it to validate my parking. My company buys stickers for parking validation which cost around $10 each. Looking a bit more at the stickers, I realized that if I knew how to generate those stickers, I could just park for free.

Those stickers had a simple “Interleaved 2 of 5” 1D barcode on them. I went home and took a picture of those barcodes…


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Over the years, I’ve collected guidelines from my professional experience at working at start-ups, building a start-up, selling a start-up, and working at a large corporate post-acquisition as a senior executive.

Although succeeding at start-ups has a huge luck component, second-timers have a higher success rate than first-timers (almost double, at least according to this very old article: https://hbswk.hbs.edu/item/performance-persistence-in-entrepreneurship).

I believe that the experience component is very substantial, and that experience comes at two flavors: What company to build, and how to build it. …

Ron Reiter

An entrepreneur, and a web expert.

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