Linux is a multi-user operating system. Different users and groups of users can be assigned permissions to handle certain files or run certain commands.

root is a special user on Linux. root is a super-user account that can see all files and has permissions to run all commands. Normally this account should only be used for administrative tasks.
root is automatically created when a Linux system is installed.
It's best practice to set up secondary user accounts and give those user accounts required permissions to perform their tasks. https://docs.rackspace.com/support/how-to/linux-server-security-best-practices/

The Linux file system is organised into files and directories. Directories are basically like folders.

Linux has standard directories for typical uses:

• /bin - binaries
• /etc - “et-see”, system configuration files (hosts file etc)
• /home - home directory for users' files
• /root - special home directory for the root user
• /usr - “unix system resources”, user related programs (static data)
• /var - variable data files, log files, files being written to constantly

https://www.howtogeek.com/117435/htg-explains-the-linux-directory-structure-explained/
https://www.geeksforgeeks.org/linux-directory-structure/
Filesystem Hierarchy Standard (FHS) https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard
History of /usr https://askubuntu.com/questions/130186/what-is-the-rationale-for-the-usr-directory

Commands https://twitter.com/mujeeb0147/status/1586324478606594050?t=NOWX0uHU7k-PnZsvqkeqOA&s=19

https://en.wikibooks.org/wiki/Bash_Shell_Scripting/Whiptail
http://akshaim.github.io/IoT/RPi/RaspberryPi-102.html
https://funprojects.blog/2022/04/06/text-interfaces-with-whiptail-and-dialog/

https://tecadmin.net/how-to-install-xrdp-on-ubuntu-22-04/