What is an operating system? An operating system is the software that supports a computer's basic functions, such as scheduling tasks, executing applications, and controlling peripherals.
Windows System: The operating system of windows is a series of interfaces that is used for personal computers. 90% of computers contain windows operating systems.
Linux system: It is the software on a computer that enables applications and the computer operator to give accessibility to the devices on the computer that are needed to perform desired functions. Linux has grown to become a force in computing, powering everything from the New York Stock Exchange to mobile phones to supercomputers to consumer devices.
Mac OS: Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems.
How do they form part of a computer system?
They are a type of low level software that is used to manage computer hardware resources and provides common services for computer programs. Application programs usually require an operating system to function.
This is what controls peripherals which include keyboards and mice etc. An example of this is windows controlling monitors by changing the resolution; mouse setting the click speed.
Windows Peripheral Management:
To get to the device manager in Windows, right click on the ‘my computer’ icon, choose properties, and then click on the device manager tab. From there you can select a variety of management options. The device manager is found in both Windows (95 and higher) and Macintosh PC platforms. Windows2000 contains an improved device manager that detects plug-and-play hardware and displays a large list of supported hardware.
Linux Peripheral Management:
Udev is the device manager for the Linux 2.6 kernel that creates/removes device nodes in the /dev directory dynamically. It is the successor of devfs and hotplug. It runs in userspace and the user can change device names using Udev rules.
Udev depends on the sysfs file system which was introduced in the 2.5 kernel. It is sysfs which makes devices visible in user space. When a device is added or removed, kernel events are produced which will notify Udev in user space.
The external binary /sbin/hotplug was used in earlier releases to inform Udev about device state change. That has been replaced and Udev can now directly listen to those events through Netlink.
Mac OS Peripheral Management:
Mac Os can control keyboard by changing the input language. For other devices like Iphone, MacOS controls screen by changing it to landscape mode.
These are security functions like firewall, user account with password protection; security however can be easily bypassed by turning on safe mode.
Security within Linux:
Security-Enhanced Linux (SELinux) is a Linux kernel security module that provides the mechanism for supporting access control security policies, including United States Department of Defense-style mandatory access controls (MAC).
SELinux is a set of kernel modifications and user-space tools that can be added to various Linux distributions. Its architecture strives to separate enforcement of security decisions from the security policy itself and streamlines the volume of software charged with security policy enforcement. The key concepts underlying SELinux can be traced to several earlier projects by the United States National Security Agency.