What is true about the su command?

The su command stands for substitute user or switch user. It allows you to run a shell or a command

as another user, usually the superuser or root. To use the su command, you need to know the

password of the target user. For example, if you want to switch to the root user, you can type su - and

enter the root password. This will give you a root shell, where you can execute commands with

administrative privileges. To exit the root shell, you can type exit or press Ctrl-D. The su command is

not the default shell of the root account, nor can it only be used by the root user. It can be used by

any user who knows the password of another user. The su command does not change the name of

the main administrator account, which is always root on Linux systems. The su command also does

not lock the root account in specific time frames, although there are other ways to do that, such as

using the pam_time module. Reference:

Linux Essentials - Linux Professional Institute (LPI), section 5.1.1

LPI Linux Essentials Study Guide: Exam 010 v1.6, 3rd Edition, chapter 9, page 219.