Useful Linux Command Line Tricks and commands
By: Pruthviraj Sonawane
Tags: System Administration, Tricks, Beginner, Linux, DevOps

When I first started using Linux and, I was using Ubuntu with Graphical User Interface, Using GUI I see Linux same as windows OS. but when I jump to the use of the Linux terminal, I truly hated the Linux Terminal, because there is no option to click on icons and use them. and remembering the all required commands and proper use is hard. With the practice, I realized the flexibility and usability of command. Today, I would like to share some useful tricks and commands with you

Show the previous command or execute them

Most of the time you will need to execute previous commands again and again, while you can press the Up-Down arrow keys to find relevant command instead of using arrow keys us history command.

# history

As you will see the last executed commands with numbers, so we just need to execute the command with the given number

!#

for example

!1 Where # should be replaced with the actual number of common that we want to execute.

Show the Information of Users

many times we need to check the available users on the server/system using the following simple command we can get the basic details of all available users.

# lslogins

Copy Console/Terminal Output into the text file

Some time while executing some command it generates a long trail of output in that case we can copy all generated output on terminal store into the text files. Even using the tee command we can store the operational output into the files.

# tee [options] ... [file]

for example

# sudo apt update | tee update.txt

SSH to the remote Servers

While working on the different servers the SSH performs a major role in the IT department. I would share the simplest way to configure SSH and login to the Server using SSH. Follow the following steps.

Step 1: Generate the Key

# ssh-keygen

Step 2: Copy the Key to the Server

# ssh-copy-id username@Server-IP

Step 3: login from the Client to Server

# ssh username@Server-IP

OR

ssh -l username server-IP

OR

ssh username@Server-IP -p port The -p port option for if ssh is not configured on default (22) port.

Rollback Updates and Patches

As the working of a System administrator or use of Linux in Daily uses we have to update the Linux and some packages. But sometimes the updated packages have compatibility issues, so in that case, we need to downgrade the package version on downgrade the update, I would Share the following steps to roll back the updates and patches.

Rollback the Package

Install a Package or Patches

# yum install git

validate the installed git version

# git --version

Check the Yum package history

# yum history

Rollback the install package

# yum history undo <ID>

example

# yum history undo 2

the package will be removed

Rollback the Updates

Install a Package or Patches

# yum update

Check the yum History

# yum history

Rollback the Updates

# yum history undo <ID>

# yum history undo 1

This is all about some useful Linux tricks and commands, We can find more useful resources for

Linux. We can say Linux is all about Knowledge hub, we find more, you learn more !!!