These quick reference guides make life and daily work easier for system administrators, and they’re all available for free.

As a systems administrator, you don’t do one job, you do all of them, and often each of them comes up at any time, anywhere, without warning. Unless you only do one task each day, you may not always have all the commands and options in your head when you need them. That’s why I like quick lists.

They can help you avoid silly mistakes, they can save you from having to wade through pages of documents, and they can help you get things done efficiently. I picked my 10 favorite quick checks for each system administrator, regardless of his or her level of experience.

network

Our Linux Network lookup table is the Swiss Army knife of lookup tables, containing simple reminders of the most common network commands, including nslookup, tcpdump, nmcli, netstat, traceroute, and more. Best of all, it uses the IP command, so you can finally stop using the ifconfig command by default!

A firewall

There are two kinds of system administrators: those who know iptables and those who use iptables configuration files written by the former. If you’re in the first category, you can continue to use your Iptables configuration with or without Firewalld.

If you’re in the second category, you can finally put aside your Iptables anxiety and embrace firewalld’s lightness. Read “Protecting your Linux Network with Firewall-cmd” and download our Firewalld Cheat sheet to remember what you’ve learned. Protecting your network ports has never been easier.

SSH

Many system administrators use POSIX shells, so it’s no surprise that a remote shell that can run on someone else’s computer is one of the most important tools on Linux. Anyone who studies server administration usually learns to use SSH early, but many of us only learn the basics.

Sure, SSH can open an interactive shell on a remote machine, but it does much more than that. For example, you need to log in graphically on a remote machine. The user of the remote host is either not near the keyboard or cannot understand your command to enable VNC. As long as you have SSH permission, you can open the port for them.

$ ssh -L 5901:localhost:5901 <remote_host>
Copy the code

Learn more in our SSH Quick Check out.

Linux users and permissions

Traditional mainframes and UNIX supercomputer-style user accounts have been largely replaced by systems like Samba, LDAP, and OpenShift. However, this does not change the need for careful management of administrators and service accounts. For this, you still need to be familiar with the commands useradd, usermod, chown, chmod, passwd, gpasswd, umask, etc.

With my Users and Permissions Checklist at hand, you’ll always have a reasonable overview of user management-related tasks, with example commands to demonstrate proper syntax for anything you need to do.

Basic Linux commands

Not all system administrators spend all their time on terminals. Whether you prefer to work on a desktop or are just starting out with Linux, sometimes it’s good to have a task-oriented reference for common terminal commands.

For an interface designed for flexibility and improvisation, it can be difficult to find everything you might need, but my Quick List of Commonly used commands is fairly comprehensive. Based on the typical life of any technical desktop user, this checklist covers commands to navigate the computer, find the absolute path to files, copy and rename files, create directories, and start system services.

Git

In the history of computing, version control was something only developers needed. But that was then, and Git is now. Version control is an important tool for anyone who wants to track changes from Bash scripts to configuration files, documentation, and code. Git is for everyone, including programmers, website reliability engineers (SRE), and even system administrators.

Get our Git Cheat sheet to learn essentials, basic workflow, and the most important Git flags.

Curl

Curl is not necessarily a tool for system administrators; technically, it is “just” a non-interactive Web browser for terminals. You might not use it for days. However, it’s likely that you’ll find Curl useful for doing things you need to do every day, whether it’s quickly referencing some information on a website, troubleshooting a web host, or verifying an important API you’re running or relying on.

Curl is a command used to send data to a server. It supports HTTP, FTP, IMAP, LDAP, POP3, SCP, SFTP, SMB, and SMTP. It’s an important web tool, so download our Curl Quicklist and start exploring Curl.

SELinux

Linux’s security policy is fine by default, with a strong separation between root and user permissions, but SELinux has improved it with a tagging system. On a host configured with SELinux, each process and each file object (or directory, network port, device, and so on) has a label. SELinux provides a set of rules to control process tags’ access to object (such as file) tags.

Sometimes you need to adjust the SELinux policy, or debug something that was not set correctly when you installed it, or dig into the current policy. Our SELinux Checklist can help.

Kubectl

Whether you’ve moved to an open hybrid cloud, a closed private cloud, or you’re still figuring out what you need to prepare for such a move, you need to know about Kubernetes. While it’s true that the cloud still requires someone to fiddle with the physical servers, your future as a system administrator is bound to involve containers, and nothing does that better than Kubernetes.

While OpenShift provides a smooth “dashboard” experience for Kubernetes, sometimes a direct approach is needed, and that’s what Kubectl provides. The next time you have to push containers around, make sure you have our Kubectl Checklist on hand.

awk

Linux has undergone many innovations in recent years, including virtual machines, containers, new security models, new initialization systems, clouds, and more. Yet some things never seem to change. In particular, system administrators need to parse and isolate information from log files and other endless streams of data. There is still no better tool for this job than the classic AWK commands of Aho, Weinberger, and Kernighan.

Of course, AWK has come a long way since it was written in 1977, and new options and features make it easier to use. But if you don’t use AWK every day, the sheer number of options and syntax can be a bit overwhelming. Download our AWK Checklist to learn how GNU AWk works.

Bonus: Bash scripting

Quick checklists are useful, but if you’re looking for something more comprehensive, you can download our Bash Scripting Manual. This guide teaches you how to incorporate all the commands and lessons you’ve learned from the checklist into scripts to help you build a ready-to-use library of automated solutions to your everyday problems. This informative book explains Bash in detail, how it works, the difference between scripts and interactive commands, how to catch errors, and more.

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Via: opensource.com/article/20/…

By Seth Kenlon (lujun9972

This article is originally compiled by LCTT and released in Linux China