• United States
Executive Editor

Must-know Linux Commands

May 01, 20193 mins

A compilation of essential commands for searching, monitoring and securing Linux systems - plus the Linux Command Line Cheat Sheet.

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Credit: Getty / Network World / IDG

It takes some time working with Linux commands before you know which one you need for the task at hand, how to format it and what result to expect, but it’s possible to speed up the process.

With that in mind, we’ve gathered together some of the essential Linux commands as explained by Network World’s Unix as a Second Language blogger Sandra Henry-Stocker to give aspiring power users what they need to get started with Linux systems.

The breakdown starts with the rich options available for finding files on Linux – find, locate, mlocate, which, whereis, to name a few. Some overlap, but some are more efficient than others or zoom in on a narrow set of results. There’s even a command – apropos – to find the right command to do what you want to do. This section will demystify searches.

Henry-Stocker’s article on memory provides a wealth of options for discovering the availability of physical and virtual memory and ways to have that information updated at intervals to constantly measure whether there’s enough memory to go around. It shows how it’s possible to tailor your requests so you get a concise presentation of the results you seek.

Two remaining articles in this package show how to monitor activity on Linux servers and how to set up security parameters on these systems.

The first of these shows how to run the same command repetitively in order to have regular updates about any designated activity. It also tells about a command that focuses on user processes and shows changes as they occur, and a command that examines the time that users are connected.

The final article is a deep dive into commands that help keep Linux systems secure. It describes 22 of them that are essential for day-to-day admin work. They can restrict privileges to keep individuals from having more capabilities than their jobs call for and report on who’s logged in, where from and how long they’ve been there.

Some of these commands can track recent logins for individuals, which can be useful in running down who made changes. Others find files with varying characteristics, such as having no owner or by their contents. There are commands to control firewalls and to display routing tables.

As a bonus, the bundle of commands includes The Linux Command-Line Cheat Sheet, a concise summary of important commands that are useful every single day. It’s suitable for printing out on two sides of a single sheet, laminating and keeping beside your keyboard.