Just like Windows, iOS, and Mac OS, Linux is an operating system. In fact, one of the most popular platforms on the planet, Android, is powered by the Linux operating system.
An operating system is software that manages all of the hardware resources associated with your desktop or laptop. To put it simply, the operating system manages the communication between your software and your hardware.
Without the operating system (OS), the software would not function.
From smartphones to cars, supercomputers and home appliances, home desktops to enterprise servers,the Linux operating system is everywhere. Linux is one of the most reliable,
secure and worry-free operating systems available.
Linux File Hierarchy
Linux File Type
Linux Permissions
Note: Umask will take effect only on the Files and Directories created after the configuration. Previous permissions will remain unchanged.
Command reference
#umask 007 (Dir = 770 / File=660)
#chmod 755 /FOLDER-NAME