Discuss in detail the Process management, Memory management, I/O and File management and Security and Protection in LINUX Operating System

Process Management:

The cpu executes a large number of programs while its main concern is the excution of uer programs, the cpu is also needed for other system activities. These activities arecalled processs. A process is a program in execution. Typically a batch job is a process. A time shared user program is a process. A system task, such as spooling is also a process. For now, a   process may be considered as a job or time shared program, but the concept is actually more general.

The Operating System is responsible for the following activities in connection with process managemet.

•   The creation and deletion of both user and system process.

•   The suspension and resumption of process.

•   The provision of mechanisms for process synchronization.

•   The provision of mechanism for deadlock handling. Memory Management:

Memory is the most expensive part in the computer system. Memory is a large array of words or bytes, each with its own address. Interaction is achieved through a sequence of reads/writes of specific memory address. The cpu fetches from a stores in memory. There are various algorithms that depend on the particular situations to manage the memory. Selection of a memory management scheme for a specific system depends upon many

factors, but especially upon the hardware design of the system. Each algorithm requires its own hardware support.

The Operating System is responsible for the following activities in connection with Memory Management.

•   Keep track of which parts of memory are currently being used and by whom.

•   Decide which processes are to be loaded into memory when memory space becomes available.

•   Allocate and deallocate memory space as needed. I/O and File Management:

One of the purpose of an Operating System is to hide the peculiarities or specific hardware devices from the user. For example in UNIX, the peculiarities of I/O devices are hidden from the bulk of the Operating System itself by the I/O System. The Operating System is responsible for the following activities in connection to I/O management.

•   A buffer caching system.

•   To activate a general device driver code.

•   To run the driver software for specific hardware devices as and when required. File Management is one of the most visible services of an Operating System. Computers can store information in several different physical forms: magnetic tapes, disk and drum are the most common forms. Each of these devices has its own characteristics and physical organisation.

The Operating System implements the abstract concept of the file by managing mass storage device such as types and disks. Also files are normally organised into directories to ease their use. Finally, when multiple users have access to files it may be desirable to control by whom and in what ways files may be accessed. The Operating System is responsible for the following activities in connection to the file management.

•   The creation and deletion of files.

•   The creation and directory.

•   The support of primitives for manipulating files and directories.

•   The mapping of files on to disk storage.

•   Backup of files on stable storage.

•   Protection and security of the files.

A Operating System for a security control system. It consist of a number of programs. One of these programs would gain control of the Operating system when it is powered o and initialize the system. The first task of this initialize program would be to reset the hardware sensors and alarms. Once the hardware initialization was complete the Operating System would enter a continual monitoring routine of all the input sensors. If the state of any input sensor is changed it would branch to an alarm generation routine.

The various processes in an Operating System must be protected from each others activities. For that purpose, various mechanisms which can be used to ensure that the files, memory segment, cpu and other resources can be operated on only by those processes that have gained proper authorization from the Operating System.