Everybody knows
sudo, right? This tool is installed by default on most Linux systems and is available for most BSD and commercial Unix variants. Still, after talking to hundreds ofsudousers, the most common answer I received was thatsudois a tool to complicate life.
Source: What you probably didn’t know about sudo, an article by Peter Czanik.
So you're a network administrator and you have a number of Linux machines in your data center. You've found some odd traffic bouncing about your network and your curiosity is piqued. Is it possible that traffic is making use of an open port on a machine? If so, where's the port and how do you close it?
On those Linux machines, the task is actually pretty simple. I want to show you how to locate an open port and close it. I'll be demonstrating on Ubuntu Server 18.04, although the process will be similar on many distributions—the only difference being how you close the port.
Source: How to locate and close an open port in Linux, an article by Jack Wallen.
See also Use nmap to find machines and open ports and What's listening on port 8080.
Being both a command and a programming language makes awk a powerful tool for tasks that might otherwise be left to
sort,cut,uniq, and other common utilities.
Source: Awk one-liners and scripts to help you sort text files, an article by Seth Kenlon.