Out command in linux

How to Log Out from Ubuntu Session [Beginner’s Tip]

The answer depends on whether you are using Ubuntu server or desktop. I’ll show you steps for both.

Logout Ubuntu from terminal (for server)

If you are using Ubuntu server and you are confined to the terminal screen, you can use the exit command:

Yes. That’s the way to logout from terminal because there is no logout command in Ubuntu or any Linux distribution. You have commands for shutdown Ubuntu but there is no separate log out command.

You may wonder if there is command for shutdown, command for restart then why there is no Linux command for logout?

The answer lies in the way Linux works. You probably know that Linux is only kernel and you need a shell to interact with the kernel. When you use a terminal or if you log in to an Ubuntu system via SSH, you open a shell session.

If you want to logout from your session, you simply exit the shell. This is why the exit command is equivalent to log out command in Linux.

Log out from Ubuntu desktop (GUI method)

If you are using Ubuntu desktop, you have a graphical interface (called desktop environment). You can use your mouse here.

I am showing the screenshot for the default GNOME desktop but if you are using some other Ubuntu desktop variants like Kubuntu, Lubuntu etc, there should also be a logout button or logout option in the power menu.

To log out from Ubuntu desktop session, go to the top right corner and click to bring the system tray. You should see Power Off / Log Out option. Click on it and it will show the Log Out option.

When you click on the Log Out button, it will open a dialogue box and ask for your conformation. If it receives no input from you, you’ll be logged out in 60 seconds.

That’s it. Now that you know how to log off from Ubuntu session let me tell you a secret tip.

You can use Ctrl+Alt+Del keyboard shortcut in Ubuntu to bring the logout menu. Cool, isn’t it?

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How to Redirect Output to a File and Stdout in Linux

In the world of Linux, redirecting output to a file or the standard output (stdout) is a fundamental technique that allows us to capture and manipulate command output efficiently.

Whether you are a beginner or an experienced user, understanding how to redirect output can greatly enhance your productivity and provide you with more control over your command-line operations.

Through this guide, you will learn the process of redirecting output to a file and stdout in Linux.

Redirecting Output to a File in Linux

At some point where you want to save or redirect command output into a specific file for any reason, like debugging. In Linux, to save the output of a file, we use stdout, which is also known as the stream command.

In computing, the stream is something that transfers data. In our case, it is text data. Using stdout, we can stream and save that data into a text file for future use.

Before proceeding ahead, First, you should know what is Redirection and a combination of operators.

A redirection symbol directly redirects the command into a file instead of showing output on a terminal. There is a combination of redirection symbols that you can use like “>” , ”>>” , ”&>” , ”&>>” .

In Linux, what we type is called “stdin”, and the output we receive is known as “stdout”. If the output file does not exist in a specific location, it will recreate automatically and save the file.

Make sure if you have used “>” , then the past data will replace with fresh command output. If you want to redirect both “stdout” and “stderr”, then use “&>” .

Now we will use this redirection symbol to redirect the output into the file.

Redirect Output to File in Linux

When you use “>” redirection operator, it will redirect command output into a specific file. If you used the same file again to redirect, then the last output will be overwritten.

We will demonstrate it using the pwd command and hostnamectl command to show system info with a redirect “>” to save output into demofile.txt.

First, we will save the current working directory output to a file.

Now we will redirect the second output into the file.

Now view the contents of the file.

Appending Output to a File in Linux

When you use this “>>” redirection operator, it will redirect command output into a specific file, and ensure that the last saved data should not get a wiped and append new output into the same file.

For example, we will again use the pwd and hostnamectl commands to show system information with a redirect “>>” to save output into demofile.txt.

$ pwd > demofile.txt $ hostnamectl >> demofile.txt $ cat demofile.txt

From the above output, you can see all the past outputs are still available in the same file.

Discard Output to “/dev/null” in Linux

Sometimes you may want to discard output entirely. In such cases, you can redirect output to the “/dev/null” device file, which acts as a black hole for data.

In this example, the ls command lists the contents of the current directory, but the output is redirected to /dev/null. This effectively discards the output, as /dev/null acts as a black hole for data. No file is created or overwritten, and the output is not visible in the terminal or saved anywhere.

Redirecting Output to Stdout in Linux

Redirecting output to stdout allows you to display command output on the terminal or use it as input for other commands.

Here are some common methods to perform this process on your Linux system.

Using “echo” Command

The echo command is another way to output text or variables to stdout; by using redirection, you can redirect the output to the terminal or a file.

$ echo "Hello, Linux Users!" > output.txt

Using “tee” Command

The “tee” command reads from standard input and simultaneously writes to both stdout and files, helping you to display output on the terminal and save it to a file simultaneously.

$ ls | tee directory_lists.txt

The above command displays the output on the terminal as soon as you execute it and save the information in the “directory_list.txt” file. You can retrieve the information from this file using the cat command later on.

Using “pip” Command

In Linux, you can chain commands together using pipes (|) to redirect output from one command as input to another. This allows you to perform complex operations.

In this example, the ls command lists the contents of the current directory, and the output is then piped (|) to the grep command, which searches for lines containing the word “file” in the output of ls, enabling you to filter the output of one command and pass it as input to another command.

Conclusion

Understanding how to redirect output to a file and stdout in Linux is a crucial skill that can greatly enhance productivity and provide greater control over command-line operations.

By utilizing methods such as using the «>» operator, appending output to a file, discarding output with “/dev/null” and redirecting output to stdout using commands like “echo,” “tee” and piping, you can streamline your workflow and efficiently manage command output in your Linux environment.

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