here we are considering the features like user convenience, support, adaptability, safety, security etc.
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.
Operating systems fall into three categories:
- Unix and Unix based operating systems (BSD and its descendants, macOS, Linux),
- Microsoft Windows and
- Other.
This comparison leaves out Unix itself and instead covers two Unix-based systems, Linux and macOS, alongside Windows. The history section below has more detail on Unix.
History of Operating System
Unix
Unix is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix. Ken Thompson, Dennis Ritchie, and others at the Bell Labs research centre started developing the original AT&T Unix in the 1970s.
Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to both academic and commercial Unix variants from vendors. In the early 1990s, AT&T sold its rights in Unix to Novell, which then sold its Unix business to the Santa Cruz Operation (SCO) in 1995.
The UNIX trademark passed to The Open Group, an industry consortium founded in 1996, which allows the use of the mark for certified operating systems that meet the Single UNIX Specification (SUS).
In the 1990s, Unix and Unix-like systems grew in popularity. They became the operating system of choice for over 90% of the world's top 500 fastest supercomputers, as a worldwide network of programmers collaborated to develop the BSD and Linux distributions. In 2000, Apple released Darwin, also a Unix system, which became the core of the Mac OS X operating system, later renamed macOS.
The Unix Operating System became a trademark, used as an open standard owned and managed by The Open Group. It enables key technologies and delivers reduced total cost of ownership, increased IT agility, stability, and interoperability in heterogeneous environments, advancing business and markets across the globe.
Linux
An earlier antitrust case barred AT&T from entering the computer business and required it to license the operating system's source code to anyone who asked. Unix grew quickly and became widely adopted by academic institutions and businesses.
In 1984, AT&T divested itself of Bell Labs; freed of the legal obligation requiring free licensing, Bell Labs began selling Unix as a proprietary product, where users were not legally allowed to change Unix.
The GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed entirely of free software. Work began in 1984. Later, in 1985, Stallman started the Free Software Foundation and wrote the GNU General Public License (GNU GPL) in 1989. By the early 1990s, developers had completed many of the programs required in an operating system, such as libraries, compilers, text editors, a command-line shell, and a windowing system. Low-level elements such as device drivers, daemons, and the kernel, called GNU Hurd, remained stalled and incomplete.
Linus Torvalds has stated that if the GNU kernel had been available at the time (1991), he would not have decided to write his own. The development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux, but legal complications delayed its release until 1992. Torvalds has also stated that if 386BSD had been available at the time, he probably would not have created Linux.
Andrew S. Tanenbaum, a computer science professor, created MINIX and released it in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn operating system principles. The complete source code of MINIX was freely available, but the licensing terms prevented it from being free software until the licensing changed in April 2000.
In the 1990s, Unix and Unix-like systems grew in popularity. They became the operating system of choice for over 90% of the world's top 500 fastest supercomputers, as a worldwide network of programmers collaborated to develop the BSD and Linux distributions. In 2000, Apple released Darwin, also a Unix system, which became the core of the Mac OS X operating system, later renamed macOS.
MacOS
The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, NeXT developed the Unix-like NeXTSTEP operating system and launched it in 1989.
The kernel of NeXTSTEP builds on the Mach kernel, which Carnegie Mellon University originally developed, with extra kernel layers and low-level user space code derived from parts of BSD. NeXT built its graphical user interface on top of an object-oriented GUI toolkit using the Objective-C programming language.
Throughout the early 1990s, Apple had tried to create a modern OS to succeed its classic Mac OS through the Taligent, Copland and Gershwin projects, but all were eventually abandoned. This led Apple to buy NeXT in 1996, allowing NeXTSTEP, then called OPENSTEP, to serve as the basis for Apple's new operating system.
The deal also brought Steve Jobs back to Apple, first as interim CEO and then as permanent CEO. He shepherded the transformation of the programmer-friendly OPENSTEP into a system that Apple's primary market of home users and creative professionals would adopt. The project was first code-named "Rhapsody" and then officially named Mac OS X.
Windows
The history of Windows dates back to 1981 when Microsoft started work on a program called "Interface Manager". Microsoft announced it in November 1983 under the name "Windows", but did not release Windows 1.0 until November 1985. Microsoft intended Windows 1.0 to compete with Apple's operating system, but it achieved little popularity. Windows 1.0 is not a complete operating system; rather, it extends MS-DOS.
Microsoft released Windows 2.0 in December 1987, and it proved more popular than its predecessor. Windows 2.03 changed the OS from tiled windows to overlapping windows. Windows 2.1 came in two different versions: Windows/286 and Windows/386.
Windows 3.0, released in 1990, improved the design. Windows 3.0 also featured improvements to the user interface. Windows 3.1, made generally available on March 1, 1992, featured a facelift. In August 1993, Microsoft released Windows for Workgroups, a special version with integrated peer-to-peer networking features and a version number of 3.11.
Microsoft released Windows 95 on August 24, 1995. Windows 95 introduced support for native 32-bit applications, plug and play hardware, and preemptive multitasking. Microsoft followed it with the release of Windows 98 on June 25, 1998. On September 14, 2000, Microsoft released Windows Me (Millennium Edition).
Microsoft released Windows XP on October 25, 2001. The introduction of Windows XP aimed to unify the consumer-oriented Windows 9x series with the architecture introduced by Windows NT.
After Windows 2000, Microsoft also changed its release schedules for server operating systems; Microsoft released the server counterpart of Windows XP, Windows Server 2003, in April 2003.
Microsoft released Windows Vista on November 30, 2006, for volume licensing, and again on January 30, 2007.
On July 22, 2009, Microsoft released Windows 7 and Windows Server 2008 R2 as RTM. Microsoft released Windows 7 to the public three months later, on October 22, 2009.
Microsoft released Windows 8, the successor to Windows 7, generally on October 26, 2012. Windows 8 introduced major changes, including a user interface based around Microsoft's Metro design language with optimizations for touch-based devices such as tablets and all-in-one PCs.
On September 30, 2014, Microsoft announced Windows 10 as the successor to Windows 8.1. Microsoft released Windows 10 on July 29, 2015.
User Convenience
Linux
Process Scheduler Implementation Linux used an O(n) scheduler with a multilevel feedback queue with priority levels ranging from 0 to 140. Levels 0-99 are for real-time tasks, and levels 100-140 count as nice task levels. The time quantum for switching processes was approximately 200 ms for real-time tasks and approximately 10 ms for nice tasks.
Some enterprise Linux distributions, such as SUSE Linux Enterprise Server, replaced this scheduler with a backport of the O(1) scheduler.
The Completely Fair Scheduler (CFS) uses a well-studied, classic scheduling algorithm called fair queuing originally invented for packet networks.
File System
Linux supports many file systems, but common choices for the system disk on a block device include the ext* family (ext2, ext3 and ext4), XFS, JFS, and btrfs. For raw flash without a flash translation layer (FTL) or Memory Technology Device (MTD), there are UBIFS, JFFS2 and YAFFS, among others. SquashFS is a common compressed read-only file system.
User Interface
Linux calls its user interface the shell. The shell takes the form of a command-line interface (CLI), a graphical user interface (GUI), or controls attached to the associated hardware, which is common for embedded systems. For desktop systems, the default user interface is typically graphical.
The dominant shell used in Linux is the Bourne-Again Shell (bash). Most low-level Linux components, including many parts of the userland, use the CLI only.
On desktop systems, the most popular user interfaces are the GUI shells, packaged together with extensive desktop environments, such as KDE Plasma, GNOME, MATE, Cinnamon, LXDE, Pantheon and Xfce, though other user interfaces exist.
Server distributions might provide a command-line interface for developers and administrators.
Four types of window managers exist for X11: tiling, flexible, stacking, and compositing. Desktop environments include window managers as part of their standard installations, such as Mutter (GNOME), KWin (KDE) or Xfwm (xfce), although users may choose to use a different window manager if preferred.
Wayland is a display server protocol intended as a replacement for the X11 protocol; as of 2014. Unlike X11, Wayland does not need an external window manager and compositing manager.
MacOS
Process Scheduler Implementation
Mac OS 9 uses cooperative scheduling for threads, where one process controls many cooperative threads, and also provides preemptive scheduling for multiprocessing tasks. The kernel schedules multiprocessing tasks using a preemptive scheduling algorithm. All Process Manager processes run within a special multiprocessing task called the "blue task". The system schedules those processes cooperatively, using a round-robin scheduling algorithm.
macOS uses a multilevel feedback queue, with four priority bands for threads- normal, system high priority, kernel-mode only, and real-time. macOS schedules threads preemptively; it also supports cooperatively scheduled threads in its implementation of the Thread Manager in Carbon.
File System
macOS uses the Apple File System (APFS), which in 2017 replaced a file system inherited from classic Mac OS called HFS Plus (HFS+). HFS Plus is a metadata-rich and case-preserving but (typically) case-insensitive file system. Due to the Unix roots of macOS, Apple added Unix permissions and journaling to HFS Plus to prevent corruption of the file system structure. Apple also introduced optimizations to the allocation algorithms in an attempt to defragment files automatically without needing an external defragmenter.
Newer versions of macOS are capable of reading and writing to the legacy FAT file systems (16 and 32) common on Windows.
They are also capable of reading the newer NTFS file systems for Windows.
macOS supports reading and writing of the exFAT file system since Mac OS X.
User Interface
The addition of Aqua marked one of the major differences between the classic Mac OS and the current macOS. Aqua is a graphical user interface with water-like elements that debuted in the first major release of Mac OS X. Spatial anti-aliasing technology draws every window element, text, graphic, or widget on-screen. Apple improved ColorSync, a technology introduced many years before, and built it into the core drawing engine to provide colour matching for printing and multimedia professionals.
Windows
Process Scheduler Implementation
Early MS-DOS and Microsoft Windows systems were non-multitasking and did not feature a scheduler. Windows 3.1x used a non-preemptive scheduler. Windows 95 introduced a rudimentary preemptive scheduler, but legacy support opted to let 16-bit applications run without preemption.
Windows NT-based operating systems use a multilevel feedback queue with 32 priority levels, 0 through to 31. Priorities 0 through 15 are "normal" priorities, and priorities 16 through 31 are soft real-time priorities that require privileges to assign.
The kernel may change the priority level of a thread depending on its I/O and CPU usage and whether the thread is interactive. This raises the priority of interactive and I/O bound processes and lowers that of CPU bound processes. Windows Vista modified the scheduler to use the cycle counter register of modern processors, tracking exactly how many CPU cycles a thread has executed rather than relying on an interval-timer interrupt routine. Vista also uses a priority scheduler for the I/O queue so that disk defragmenters and other such programs.
File System
Windows makes use of the FAT, NTFS, exFAT, Live File System, and ReFS file systems. Windows Server 2012, Windows Server 2016, Windows 8, Windows 8.1, and Windows 10 are the only versions that support and can use ReFS; Windows cannot boot from it.
Windows uses a drive letter abstraction at the user level to distinguish one disk or partition from another. The path C:\WINDOWS represents a directory WINDOWS on the partition represented by the letter C. Drive C: is most commonly used for the primary hard disk drive partition, on which Windows is typically installed and from which it boots.
User Interface
Modern versions of the Microsoft Windows operating system use the Windows shell as their shell. Windows Shell provides a desktop environment, start menu, and taskbar, as well as a graphical user interface for accessing the file management functions of the operating system. Older versions also include Program Manager, which was the shell for the 3.x series of Microsoft Windows. Program Manager shipped with later versions of Windows of both the 95 and NT types, at least through Windows XP.
Support
Linux
Many popular applications are available across Linux, macOS, and Windows. Mozilla Firefox, OpenOffice.org/LibreOffice, and Blender have downloadable versions for all major operating systems. Developers ported some applications initially built for Linux, such as Pidgin and GIMP, to other operating systems (including Windows and macOS) because of their popularity. A growing number of proprietary desktop applications also run on Linux, such as Autodesk Maya and The Foundry's Nuke in the high-end field of animation and visual effects. See the list of proprietary software for Linux for more details. Many companies have ported their own or other companies' games to Linux, and Linux is also a supported platform on both the popular Steam and Desura digital distribution services.
Many other types of applications available for Microsoft Windows and macOS also run on Linux. Commonly, either a free software application exists that performs the functions of an application found on another operating system, or that application has a version that works on Linux. Examples include Skype and video games like Dota 2 and Team Fortress 2. The Wine project also provides a Windows compatibility layer to run unmodified Windows applications on Linux. Commercial interests, including CodeWeavers, sponsor the project; CodeWeavers also produces a commercial version of the software.
Servers A broad overview of the LAMP software bundle displayed here together with Squid. A high-performance and high-availability web server solution providing security in a hostile environment.
Linux distributions have long served as server operating systems and have risen to prominence in that area. Netcraft reported in September 2006 that Linux distributions ran on eight of the ten most reliable internet hosting companies' web servers (the other two ran an "unknown" OS), with Linux in the top position. In June 2008, Linux distributions represented five of the top ten, FreeBSD three of ten, and Microsoft two of ten. Since February 2010, Linux distributions represented six of the top ten, FreeBSD three of ten, and Microsoft one of ten, with Linux still in the top position.
Embedded devices Due to its low cost and ease of customization, Linux is often used in embedded systems. In the non-mobile telecommunications equipment sector, the majority of customer-premises equipment (CPE) hardware runs some Linux-based operating system. OpenWrt is a community-driven example that many OEM firmware releases build upon.
MacOS
macOS has supported three major processor architectures, beginning with PowerPC-based Macs in 1999. In 2006, Apple transitioned to the Intel architecture with a line of Macs using Intel Core processors. In 2020, Apple began the Apple silicon transition, using self-designed, 64-bit ARM-based Apple M1 processors on new Mac computers.
Since most Mac hardware components, or components like those, have been available to buy since the Intel transition, some technology-capable groups have developed software to install macOS on non-Apple computers. People refer to these as Hackintoshes. This violates Apple's EULA, and Apple does not support it through technical support, warranties, and so on. Still, Apple has generally ignored communities that cater to personal users who do not install for resale and profit.
These self-made computers allow more flexibility and customization of hardware but at a cost of leaving the user more responsible for their machines, such as on matters of data integrity or security. Apple sued Psystar, a business that attempted to profit from selling macOS on non-Apple certified hardware, in 2008.
Windows
Windows NT included support for three different platforms before the x86-based personal computer became dominant in the professional world. Windows NT 4.0 and its predecessors supported PowerPC, DEC Alpha and MIPS R4000. But Windows 2000, the successor of Windows NT 4.0, dropped support for all platforms except the third generation x86 (known as IA-32) or newer in 32-bit mode. The client line of the Windows NT family still runs on IA-32, although the Windows Server line has ceased supporting this platform with the release of Windows Server 2008 R2.
With the introduction of the Intel Itanium architecture (IA-64), Microsoft released new versions of Windows to support it. Microsoft released Itanium versions of Windows XP and Windows Server 2003 alongside their mainstream x86 counterparts. Windows XP 64-Bit Edition, released in 2005, is the last Windows client operating system to support Itanium. Windows Server line continues to support this platform until Windows Server 2012; Windows Server 2008 R2 is the last Windows operating system to support Itanium architecture.
On April 25, 2005, Microsoft released Windows XP Professional x64 Edition and Windows Server 2003 x64 Editions to support the x86-64 (or simply x64), the eighth generation of x86 architecture. Windows Vista was the first client version of Windows NT that Microsoft released simultaneously in IA-32 and x64 editions. x64 is still supported.
Microsoft created an edition of Windows 8 known as Windows RT for computers with ARM architecture. ARM is still used for Windows smartphones with Windows 10, but Microsoft will not update tablets with Windows RT. Starting from the Windows 10 Fall Creators Update, Windows includes support for PCs with ARM architecture.
Windows CE
Windows CE (officially known as Windows Embedded Compact), is an edition of Windows that runs on minimalistic computers, like satellite navigation systems and some mobile phones. Windows Embedded Compact runs on its own dedicated kernel, dubbed the Windows CE kernel. Microsoft licenses Windows CE to OEMs and device makers.
Xbox OS
People unofficially call the version of Windows that runs on the Xbox One "Xbox OS." This implementation puts a specific emphasis on virtualization, using Hyper-V. It runs three operating systems at once: the core operating system, a second one for games, and a more Windows-like environment for applications.
Microsoft updates Xbox One's OS every month. Users can download these updates from the Xbox Live service to the Xbox and install them, or use offline recovery images downloaded via a PC. The Windows 10-based Core replaced the Windows 8-based one in this update, and people sometimes refer to the new system as "Windows 10 on Xbox One" or "OneCore".
Adaptability
Linux
Linux distributions cover a spectrum from general-purpose use on desktops and servers to specialization for narrower purposes. These specialized purposes include computer architecture support, embedded systems, stability, security, localization to a specific region or language, targeting of specific user groups, support for real-time applications, or commitment to a given desktop environment. Some distributions deliberately include only free software. As of 2015, over four hundred Linux distributions are actively developed, with about a dozen distributions being most popular for general-purpose use.
Many quantitative studies of free/open-source software focus on topics including market share and reliability, with research examining Linux. The Linux market is growing rapidly, and analysts expected the revenue of servers, desktops, and packaged software running Linux to exceed $35.7 billion by 2008. Analysts and proponents attribute the relative success of Linux to its security, reliability, low cost, and freedom from vendor lock-in.
According to web server statistics as of November 2018, the estimated market share of Linux on desktop computers is around 2.1%. In comparison, Microsoft Windows has a market share of around 87%, while macOS covers around 9.7%.
W3Cook publishes stats that use the top 1,000,000 Alexa domains, which as of May 2015 estimate that 96.55% of web servers run Linux, 1.73% run Windows, and 1.72% run FreeBSD.
MacOS
As of July 2016, macOS is the second-most-active general-purpose desktop client operating system used on the World Wide Web, following Microsoft Windows. It has a 4.90% usage share, according to statistics compiled by the Wikimedia Foundation. For web browsing, macOS ranks second among desktop operating systems, after Windows, at approximately five times the usage of Linux (which has 1.01%). Usage share generally continues to shift away from the desktop and toward mobile operating systems such as iOS and Android.
Windows
Net Applications tracked the use of operating systems in devices active on the Web. According to its data, Windows was the most used operating system family on personal computers in April 2020, with around 88% usage share. Including personal computers of all kinds (e.g. desktops, laptops, mobile devices, and game consoles), Windows OSes accounted for 35.84% of usage share in May 2020.
Safety and Security
Linux
There are many Linux distributions created with privacy, secrecy, network anonymity and information security in mind, including Tails, Tin Hat Linux and Tinfoil Hat Linux. Lightweight Portable Security is a distribution based on Arch Linux and developed by the United States Department of Defense. Tor-ramdisk is a minimal distribution created solely to host the network anonymity software Tor.
Kali Linux is a Debian-based Linux distribution designed for digital forensics and penetration testing. It comes preinstalled with software applications for penetration testing and identifying security exploits. The Ubuntu derivative BackBox provides pre-installed security and network analysis tools for ethical hacking.
The Arch-based BlackArch includes over 2100 tools for pen-testing and security research.
Security-Enhanced Linux (SELinux) is a Linux kernel security module that provides a mechanism for supporting access control security policies, including mandatory access controls (MAC). SELinux is a set of kernel modifications and user-space tools that developers have added to many Linux distributions. Its architecture strives to separate enforcement of security decisions from the security policy and minimizes the amount of software involved with security policy enforcement. The key concepts underlying SELinux trace back to earlier projects by the United States National Security Agency (NSA).
MacOS
In its earlier years, Mac OS X enjoyed a near-absence of the types of malware and spyware that have affected Microsoft Windows users. In 2006, worms and potential vulnerabilities came to light, leading anti-virus companies to issue warnings that Apple's Mac OS X is not immune to malware.
In early 2011, Mac OS X experienced a large increase in malware attacks, and malware such as Mac Defender, MacProtector, and MacGuard became an increasing problem for Mac users. At first, the malware installer required the user to enter the administrative password, but later versions installed without user input.
Initially, Apple instructed its support staff not to assist in the removal of the malware or admit the existence of the malware issue. But as the malware spread, Apple issued a support document.
Apple announced an OS X update to fix the problem. The malware affected an estimated 100,000 users. Apple releases security updates for macOS regularly, as well as signature files containing malware signatures for Xprotect, an anti-malware feature part of File Quarantine present since Mac OS X Snow Leopard.
Windows
Microsoft originally designed consumer versions of Windows for ease-of-use on a single-user PC without a network connection, and these versions did not have security features built in from the outset. But Microsoft designed Windows NT and its successors for security (including on a network) and multi-user PCs.
These design issues, combined with programming errors (e.g. buffer overflows) and the popularity of Windows, make Windows a frequent target of computer worm and virus writers. In June 2005, Bruce Schneier's Counterpane Internet Security reported that it had seen over 1,000 new viruses and worms in the previous six months. In 2005, Kaspersky Lab found around 11,000 malicious programs – viruses, Trojans, back-doors, and exploits written for Windows.
While the Windows 9x series offered the option of profiles for more than one user, they lacked access privileges and did not allow concurrent access, meaning they were not true multi-user operating systems. They also implemented only partial memory protection, and were widely criticised for lack of security.
Windows Vista introduced a privilege elevation system called User Account Control. When a standard user logs in, Windows creates a logon session and assigns a token containing only the most basic privileges. This way, the new logon session cannot make changes that would affect the entire system. When an application requests higher privileges, or when the user clicks "Run as administrator," UAC prompts for confirmation. If the user gives consent (including administrator credentials, if the account requesting the elevation is not a member of the Administrators group), UAC starts the process using the unrestricted token.
In August 2019, computer experts reported that the BlueKeep security vulnerability, CVE-2019-0708, potentially affects older unpatched Microsoft Windows versions via the program's Remote Desktop Protocol, allowing for the possibility of remote code execution. They found related flaws, collectively named DejaBlue, that may also affect newer Windows versions (i.e., Windows 7 and all recent versions).
According to cvedetails.com, Debian (Linux distribution) found 5048 vulnerabilities, Ubuntu (Linux distribution) found 2971 vulnerabilities, MacOsX found 2758 vulnerabilities and Windows 10 found 2238 vulnerabilities.