Linux is an important part of our lives, especially as a system administrator. This article shares the Linux commands that I can’t live without. So, let’s begin.

Command 1: pwd

In Linux, everything is a file and we move here and there, in and out of directories. This practice eventually leaves us confused about where we stand. You should know the pwd command to see your present working directory.

pwd output

Command 2: ping

Ping is an important command for seeing whether hosts are alive or not. We can use ping for various purposes, such as finding host IP addresses, finding latency, or reverse pinging to find a hostname.

ping output

Command 3: passwd

Passwd is also another command that I can’t live without. Forgetting passwords is a common problem for all of us, hence we can use this command to change the password for any user as long as we have the authority to do so.

passwd output

Command 4: netstat

A very important command is netstat. This tool helps us to administer many resources, such as network connections (TCP/UDP), open ports, and connection statuses, along with seeing routing tables and interfaces. Mostly, I use netstat to see what ports are open in the server.

netstat output

Command 5: chmod

Chmod is definitely one of the most important commands that we use and can’t live without. This command lets you change file permissions, and it can revoke your access as well.

chmod output

Command 6: ls

A simple but widely used command is ls. This command helps you list directories and see permissions, the owner of files/directories, groups, file sizes, and dates modified. As you can see, this single command can provide us with a lot of information.

ls output

Command 7: df

Another important command that we really need is df. Using this command, we can see the free disk space on our computer. Disk management is an important task that you need to stay on top of when you are doing system administration.

df output

Command 8: kill

Kill is the one most important commands. We can use it to terminate a process using SIGTERM (kill -15 PID), or we can go for a direct kernel-level kill using SIGKILL (kill -9 PID). This command comes handy when there are many zombie processes.

kill output

Command 9: dmesg

The dmesg command is used to print the kernel’s message buffer. This is another important command that you cannot work without. It is much easier to troubleshoot a system when you can see what is going on, and what happened behind the scenes.

dmesg output

Command 10: less

Most people run into problems when viewing logs or trying to see what is going behind the scenes. The less command shows you everything. Using less with another command lets you see the command’s output or file’s contents one page at a time. This behavior increases readability.

less output

Command 11: cat

Cat is also one of the most widely used Linux commands. It lets us see the contents without having to open the file, which comes in handy when you need to see contents that are susceptible to change.

cat output

Wrapping up

So there you have it. Eleven Linux commands that most sysadmins can’t live without!

Want to try out Red Hat Enterprise Linux? Download it now for free.


執筆者紹介

Prabesh has been working as a system administrator and currently resides in Melbourne, Australia. He is a  Linux lover and has been using RHEL for over 4 years. He spends much of his time working with Linux OS and the kernel. He is currently focused on growing a more in-depth knowledge of Linux OS as a whole. 

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