chvt Command in Linux

Introduction

This lab provides a practical guide to the Linux chvt command, essential for any systemadmin. You'll discover how to switch between virtual terminals (VTs) or consoles, understanding their function and the methods to navigate them. Learn to use the chvt command effectively and explore automation techniques. This tutorial offers real-world examples and step-by-step instructions, empowering you to manage virtual terminals proficiently.

This lab is divided into three key sections: understanding the chvt command, mastering the art of switching between virtual terminals, and learning how to automate VT switching. Upon completion, you'll possess a strong understanding of the chvt command, enabling you to elevate your Linux system management capabilities.

Understand the chvt Command

This section introduces the chvt command, a fundamental tool in Linux for system administrators. chvt, short for "change virtual terminal", enables seamless switching between various virtual terminals (VTs) or consoles on your Linux system.

Virtual terminals are independent login sessions operating in the background. You can transition between these sessions using keyboard shortcuts or directly with the chvt command. This functionality is invaluable for tasks such as monitoring system logs, managing long-running processes, or accessing distinct environments within your Linux system.

To utilize the chvt command, execute the following:

sudo chvt <terminal_number>

Replace <terminal_number> with the desired virtual terminal number. For instance, sudo chvt 2 will direct you to virtual terminal 2.

Example output:

$ sudo chvt 2

The chvt command can also be used to display a list of available virtual terminals:

sudo chvt -l

Example output:

$ sudo chvt -l
VT1
VT2
VT3
VT4
VT5
VT6

This will present a listing of all available virtual terminals on your system, providing a clear overview of your options.

Switch Between Virtual Terminals

This section focuses on the practical application of switching between different virtual terminals (VTs) on your Linux system.

Begin by listing the currently available virtual terminals using the chvt command:

sudo chvt -l

Example output:

VT1
VT2
VT3
VT4
VT5
VT6

As demonstrated, this particular system has 6 virtual terminals readily available.

You can quickly switch between these virtual terminals using the following keyboard shortcuts:

  • Ctrl + Alt + F1: Switch to virtual terminal 1
  • Ctrl + Alt + F2: Switch to virtual terminal 2
  • Ctrl + Alt + F3: Switch to virtual terminal 3
  • And so forth, up to Ctrl + Alt + F6 for virtual terminal 6

Experiment with these shortcuts to navigate between virtual terminals. For instance, press Ctrl + Alt + F2 to access virtual terminal 2.

Alternatively, you can achieve the same result using the chvt command:

sudo chvt 3

This command will directly switch you to virtual terminal 3.

Example output:

$ sudo chvt 3

Observe how the terminal prompt alters as you transition between virtual terminals, signifying the change in your working environment.

Automate Virtual Terminal Switching

This final section details how to automate the process of switching between virtual terminals (VTs) using a simple script, a valuable skill for any systemadmin.

First, create a script to handle the switching between virtual terminals:

nano ~/project/switch_vt.sh

Populate the script with the following content:

#!/bin/bash

for i in {1..6}; do
  sudo chvt $i
  echo "Switched to virtual terminal $i"
  sleep 2
done

This script iterates through virtual terminals 1 to 6, pausing for 2 seconds between each switch, allowing you to observe the transition.

Save the file and exit the editor.

Grant the script execute permissions:

chmod +x ~/project/switch_vt.sh

You can now execute the script to automatically cycle through the virtual terminals:

~/project/switch_vt.sh

Example output:

Switched to virtual terminal 1
Switched to virtual terminal 2
Switched to virtual terminal 3
Switched to virtual terminal 4
Switched to virtual terminal 5
Switched to virtual terminal 6

To further enhance automation, consider scheduling this script to run automatically via a cron job or a systemd service, tailoring the implementation to your specific requirements and use case. This is particularly useful in a root context where continuous monitoring across multiple terminals is required.

Summary

In this lab, you've gained a comprehensive understanding of the chvt command in Linux. You've learned how this command enables you to switch between different virtual terminals (VTs) or consoles on your system. You've discovered that virtual terminals are essentially separate login sessions running concurrently, and you can navigate between them using either keyboard shortcuts or the chvt command directly. Furthermore, you can now list available virtual terminals and effectively switch between them using both keyboard shortcuts and command-line instructions.

You then learned to automate the process of switching between virtual terminals. Mastering this technique is useful for a variety of tasks, including monitoring system logs, managing long-running processes, or providing access to different environments, all crucial for efficient systemadmin tasks on your Linux server.

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