How can dual passwords be set up on the Linux system?

In a Linux system, it is possible to set up dual passwords by utilizing password encryption technology.

Here is a common method for setting up dual passwords:

1. Open the terminal and log in to the system as the root user.
2. Run the following command to modify the PAM (Pluggable Authentication Modules) configuration file:
3. View the /etc/pam.d/passwd file.
4. Find the following line in the open file:
5. The password must meet certain requirements before it can be used, with the pam_pwquality module attempting to check it first and allowing for up to three retries.
6. Add the following two lines below this one.
7. You must have a password in order to use the sha512 encryption with the pam_unix.so module for shadow, and the use_authtok option is also necessary. Additionally, you have the choice to use the pam_gnome_keyring.so module for password storage.
8. Save and close the file.
9. Run the following command to set a new password:
10. password
11. Enter the first password, then press the Enter key.
12. The system will prompt you to re-enter your password, input the second password, and then press the Enter key.
13. Restart the system for the settings to take effect.

Now, you will need to enter two different passwords to log into the system. Please note that this setup may have some impact on the system security, so it is important to carefully consider when using it.