System & Network Admin

Bash doesn't have a strong type system. To allow type-like behavior, it uses attributes that can be set by a command. ‘declare’ is a bash built-in command that allows you to update attributes applied to variables within the scope of your shell. In addition, it can be used to declare a variable in longhand. Lastly, it allows you to peek into variables.

In this quick tip, you'll learn to split a string into an array in Bash script.

In the first article in this series, you created a very small, one-line Bash script

ShellCheck finds bugs in your shell scripts

Journey on how UniFi Dream Machine Pro’s Dynamic DNS is setup and how to have it point to a custom Dynamic DNS provider.

Let's Encrypt is a new certificate authority. It is a huge improvement over the manual complex process of acquiring and …

When you get a certificate from Let’s Encrypt, our servers validate that you control the domain names in that certificate using “challenges,” as defined by the ACME standard. Most of the time, this validation is handled automatically by your ACME client, but if you need to make some more complex configuration decisions, it’s useful to know more about them. If you’re unsure, go with your client’s defaults or with HTTP-01.

In the following examples, I'll show how to renew certs with domains hosted on AWS/Route53 and GoDaddy. I run certbot with scripts within a docker container (to simplify automation), however you can use CLI.

How to obtain a Let's Encrypt certificate through a DNS Challenge.

My domain is: https://arenlor.com/ I ran this command: certbot certonly --rsa-key-size 4096 --staple-ocsp --server 'https://acme-v02.api.letsencrypt.org/directory' --dns-rfc2136 --dns-rfc2136-credentials /etc/letsencrypt/rfc2136.ini -d arenlor.com -d '*.arenlor.com' It produced this output: Saving debug log to /var/log/letsencrypt/letsencrypt.log Plugins selected: Authenticator dns-rfc2136, Installer None Obtaining a new certificate Performing the following challenges: dns-01 challenge for ar...

The sudoers file contains a set of rules that determines which users or groups are granted with sudo privileges as well as the level of the privileges.

If youre even a moderate Linux command line user, you must be aware of pipes, a fundamental command line feature that allows processes to communicate...

Benchmarks & Tips for Big Data, Hadoop, AWS, Google Cloud, PostgreSQL, Spark, Python & More...

There arent many viruses made for Linux distributions and as such, most people who use such systems dont even bother using antivirus software. Those...

Simplify the complex world of interface configuration files with this handy tutorial.

EnigmaBBS is a simple yet powerful modern BBS software for Linux. Learn how to install it today and relive the BBS experience of the 90s.

Here are some tips and tricks to automating file edits from the Linux command line.

No one wants to write bad code, but inevitably bugs will be created.

Rate Limiting With nginx. This article explains how to use the nginx HttpLimitReqModule to limit the number of requests for a given session. This is u...

The fmt command is a trivial text formatter. Here's how I use it to format text and email replies.

Jack Wallen walks you through everything you need to know about masked services in Linux.

In this article, we will be more interested in the dwebp command-line tool to successfully convert our sample raw WebP image file to PNG and JPEG image files.

Secure Login with FIDO2

Comparing directories in Linux might seem like a light and dismissive task for a user just starting to explore the milestones associated with using Linux.

This article describes how to mount and unmount an ISO image on a Linux Operating system to access and list the content of files.