Pos 355 - Unix®, Linux®, Mac Os®, Windows® Os Comparison Paper

Unix®, Linux®, Mac OS®, Windows® OS comparison Paper

POS - 355

December 21st, 2015

Carol Eichling

 Unix®, Linux®, Mac OS®, Windows® OS comparison Paper

With all the Operating Systems (OS) available in today’s market, how do you choose, how do you know which OS will work best for your home or business? Are you a home user that does mainly photo editing, well then maybe Mac OS is for you. Are you a small business looking for an OS with excellent security, perhaps Linux is what you are looking for. Maybe you want to build a small data system and reliability is what you need, Unix would be your OS. And finally there are the rest of us whom use Windows. This comparison paper will cover the Memory management, Process management, File management and Security of Unix®, Linux®, Mac OS®, and Windows® OS.

Unix®

Memory management

        Unix memory management is the most important part of the Unix kernel. The memory and the CPU have to work together to accomplish any computing tasks. Swapping and paging are the schemes of memory management that are used the most in modern operating systems. The swapping scheme was adopted by Unix systems in 1974, while the paging scheme was not added till 1985. Because the physical memory is not infinite, memory management becomes very important. Memory management is responsible for allocate the proper amount of memory for a new process. Swapping is when parts of the memory are swapped to the hard drive and back to the memory. Paging is when the memory is not enough to hold the process and the remaining addressed memory is stored on the hard disk drive (Liu, Yue, 2011).

Process management

A special environment is created when an application is execute in a UNIX system. Process can be started in two ways; Foreground and Background. Foreground is the default state a process run in, however only one foreground process can be ran at a time. Running a process in the background allow other commands to be ran. Process ID or PIDs are unique five digit ID number the operating system uses track processes. Unix assigns two PID numbers two a process: child Process ID (PID) and Parent Process ID (PPID). When a child PID is terminated, the parent PPID can create a new child PID or perform other tasks. It is possible to terminate a parent PPID leaving the child PID in an orphan state with only one task.  Terminating a process can also leave it in a Z state when ps list is used. The Z state or Zombie, this occurs when a process incorrectly terminates and remains as a process, however is not being used (UNIX Tutorial).  

File management

When it comes to Unix File Management there all files are organized three types. These types of files are organized into structure called the filesystem. They are as follows Ordinary Files, Special Files, and Directories.  With an Ordinary File the contain text, data, and program instruction.  The Special Files let you access the different hardware’s of a computer.  Then with Directories are basically the storage areas for both special and ordinary files PC users know them as folders (UNIX Tutorial).  

Security

The most important security feature in Unix is the permissions system. Unix-style filesystem have permissions that can be set on all files, enabling different access to a file. Chmod command is used to set permissions on a file from the command line. Unix also offers more advanced features that include the Access Control List concept. This enables permissions to be granted to several individual users or groups. The Access Control List (ACLs) is used when granting permission to users or groups to a specific file or folder. Unix-based operating systems (OS) are not susceptible to invasion by most Microsoft Windows viruses. This is due to the binaries that are created to run on Windows and will not run on Unix (Levie, 2002).

Linux®

Memory management

Linux uses a virtual memory system. A virtual memory system allows the addresses that the users program sees, dose not directly relate the physical addresses used by the hardware. Virtual memory adds a layer of indirection that provides several features to Linux’s virtual memory system. Programs running in the virtual memory on the system can provided a lot more memory compared to physically memory. Even single processes are provided a virtual address pool with larger than the system's physical memory will allow. Playing with the process's address space, allows the program in virtual memory to do number of features, such as mapping the program's memory to device memory (Corbet, 2005).

Process management

        In Linux, a process fork is an operation whereby a process creates a copy of itself by a system call fork (), which creates a new process by cloning an existing one. The process that duplicates results in parent and the new cloned process is called the child. The parent continues the execution and the newly cloned child process starts execution at the same place, based on when the call was returned. After a fork () is made, a new execute can be made, with a different program. The exec*() is a family of function calls that is used to create a new address space in the CPU and can load a new program. When a program exits, it uses the exit () system call. This system call will terminate the process and frees all its resources it was using. Another name for a process is a task. The Linux kernel internally refers to processes as tasks (Love, 2005).

File management

        Linux file management is known as a filesystem. The file system consists of two types of file structures. The first one is the entire hierarchy of directories or commonly referred to as the directory tree.  The entire hierarchy of directories begins with the root and contains subdirectories and further subdirectories. The second filesystem type is used for storing data such as the user’s files and folders and is stored on a partition on the hard disk. The two types of file mismanagement within Linux have its own set of rules used to control the allocation of disk space for each files and folder depending on the amount of data. The Meta data that contains the information such as the filenames, permissions and creation date are also stores there (Filesystems, 2004).

Security

Linux is one of the more secure systems.  Hackers try to corrupt the more common systems and the ones that are more vulnerable which is the Windows operating system.  Just like Windows you secure Linux with different essentials like a firewall, wireless security, and also disabling any unused services on the Linux system.

Mac OS®

Memory management

When it comes to Mac Memory management the systems uses what is called ARC system.   This stands for “Automatic Reference Counting”.  This makes memory management pretty much automatic for mac users.  The Mac system calls files objects, you still have to release objects or keep them if you are not sure if they have been already done so.  In the PC world we would call it saving and deleting an item (Kessler, 2009).