> File systems use permissions and attribute to regulate the level of interaction that system processes can have with files and directories chmod is a command n Linux and other Unix-like operating systems that allows changing the permissions (or access mode) of a file or directory.
> RPM (red hat package manager) is a default open source and most popular package management utility for red hat based systems like (RHEL, Centos, and Fedora). The tool allows system administrator and users to install, update, uninstall, query, verify and manage system software packages n Unix/Linux operating systems.
> root is the username or account that by default has access to all commands and files on a Linux or other Unix-like operating system. It is also referred to as root account, root user, and the superuser.
> Its sched, as per Linux 3 13 start kernel () first calls sched_init() and userspace process initi.e rest _init() creates a kernel thread passing another function kernel_init() as the point and kernel goes to idle unless called.
> The first thing kernel does is to execute the init program. Init is the root/parent of all processes executing on Linux. Based on the appropriate run-level, scripts are executed to start various processes to run the system and make it functional.