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3.Operating System - Services




Program Execution: The OS is responsible for executing programs. It loads the program into memory and executes the program. Program execution also includes process sync, process communication, and deadlock handling. 

I/O Operation: An I/O subsystem comprises I/O devices and their corresponding driver software. I/O operation means read or write operation with any file or any specific I/O device. OS provides the access to the required I/O device when required.

File System Manipulation: A file represents a collection of related information. A file system is normally organized into directories for easy navigation and usage. The operating system gives the permission to the program for operation on file. Permission varies from read-only, read-write, denied, and so on. Operating System provides an interface for the user to create/delete files. Operating System provides an interface for the user to create/delete directories. Operating System provides an interface to create the backup of file system.

Communication: In the case of distributed systems which are a collection of processors that do not share memory, peripheral devices, or a clock, the operating system manages communications between all the processes. Multiple processes communicate with one another through communication lines in the network. The OS handles routing and connection strategies, and the problems of contention and security. Both the processes can be on one computer or on different computers, but are connected through a computer network. Communication may be implemented by two methods, either by Shared Memory or by Message Passing.

Error Handling: Errors can occur anytime and anywhere. An error may occur in the CPU, in I/O devices, or in the memory hardware. The OS constantly checks for possible errors. The OS takes an appropriate action to ensure correct and consistent computing.

Resource Management: In the case of multi-user or multi-tasking environment, resources such as main memory, CPU cycles and files storage are to be allocated to each user or job. The OS manages all kinds of resources using schedulers. CPU scheduling algorithms are used for better utilization of CPU.

Protection: Considering a computer system having multiple users and concurrent execution of multiple processes, the various processes must be protected from each other's activities. The OS ensures that all access to system resources is controlled. The OS ensures that external I/O devices are protected from invalid access attempts. The OS provides authentication features for each user by means of passwords.  

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