What are the services provided by an OS with multiple users?

Before discussing about the services provided by operating system with multiple users, let us recall the services that operating system itself provides what services −

Operating system services

An operating system provides services to programs and to the users also. It mainly provides the environment for programs to execute and makes the programming task easier.

Common services

The common services are as follows −

Program execution

Operating system loads the program into CPU memory for execution and it is able to end its execution either normally or abnormally.

I/O operation

Operating system provides any I/O devices that are required for the program.

File system manipulation

Programs need to modify the files whenever required, OS allows to do modifications for the files by giving permissions.

Communication

Communication between the systems or processes can be implemented with the help of a network and is allowed or supported by the OS.

There are two types of communications which are as follows −

• Shared memory

• Message passing

Services with Multiple Users

Now let us see the services provided by OS with multiple users −

Resource allocation

If there are more than one user running at same time, then resources have to be allocated to each of them.

OSes that manage different types of resources require special allocation code like main memory, CPU cycles, file storage.

There are some resources which require only general request for allocating CPU, the CPU scheduling algorithms are used for better utilization of CPU.

Accounting

Logs of each user have to be kept, it is also necessary to keep which user, what resources, how much need to be kept track.

The accounting data may be used for billing and maintaining statistics. It also improves system efficiency.

Protection

It involves ensuring all access to system resources is controlled. Security starts with each user having to authenticate to the system.

External I/O devices are protected from invalid access attempts. All the access to the resources is controlled.