What is tty in Linux and How It works?

What is tty in Linux and How It works.
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Linux is an open-source operating system (OS). Here open source means that we can modify the source code of Linux according to us. Linux operating system shows everything in a file system, even the hardware devices that we attached and the terminal we use also appears as a file in Linux. And to see the information related to the terminal which is shown as a file, a command has also been set, called tty. The tty command basically prints the filename of the terminal associated with the standard input.

FAQ Related tty command :

  • What is tty in Linux?
  • What is tty7 in command line?
  • How tty command works?
  • How to make tty only return exit status?

So these are some of the most frequently asked questions, and here’s the answer…

What is tty in Linux?

TTY is actually a mythological technology-based name, it belongs to early-age computers, at which time computers had teletypewriters as terminals, so you could see the output of printed programs.

In Linux, tty is the physical terminal from which you logged in. In most of the cases, tty7 is where your window manager runs and from which you login. It displays terminal related information. This command allows you to interact with the system by going to the system’s data that you input, and displaying the output produced by the system.

As I mentioned above, the tty command basically prints the file name of the terminal connected to standard input and following is its syntax:

tty [OPTION]…

And here’s how the tool’s man page explains it:

Print the file name of the terminal connected to standard input.

How tty command works?

Using tty command is so easy, you don’t have to type anything long, just type “tty” and run the command, it will print the file name of the terminal connected to standard input. You can also use “who” or “w” command to find out terminal. Apart from Linux this command is also available on Solaris, FreeBSD, and other Unixish operating systems.

Example:

I typed the command

tty

It showed me the following output, on my Linux system:

/dev/pts/0

Note: – If it is not running inside a terminal, then the command produces a message like “not a tty.”

What is tty7 in Command Line

This one is one of the most asked questions, most of the Linux users have this question that whenever they typed the who command, they see their user name and date and tty7. But they don’t know what tty7 is. Although I have mentioned about it earlier in this article, but once again let’s understand it, properly and in easy words.

As we all know Linux is a multi-user system, which allows many users to work on it simultaneously on different terminals. Usually, there are seven terminals (including the one you are working on so far) on a Linux operating system, and you can log into them as different users to conducts different works.

We can work on all at the same time, so on which virtual terminal we are working on, we get information about it from the tty at the top. Any number from 1 to 7 can be written next to tty, this number shows us which terminal we are working on right now. And why we see tty7 most of the time, is because tty7 is the physical terminal in which we usually logged in. And most of the time, tty7 is where our window manager runs.

How to Navigate Between Different tty(terminals)

So it is easy to change the terminal, you can navigate between all the 7 terminals by using the following command.

Ctrl + Alt + Fn (1 to 7) key

If you want to go to tty1 you can press ctrl + alt + F1, and for tty 2 ctrl + alt + F2, for tty3 ctrl + alt + F3 and thus just by changing the function key, you can go to the rest of the terminal.

Options

There exists a command-line option -s which silences the tty command to generate no output. Just the exit status is returned. There are some other options also…

tty -s

It does is produce an exit value, however:

  • 0 if standard input is a terminal
  • 1 if standard input is not a terminal
  • 2 if given incorrect arguments
  • 3 if a write error occurs

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So this is everything about the tty command in Linux. Hopefully you have got the answers to all your questions, still, if you want to know more about tty in Linux, you can ask us in the comments section.

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