Operating system services
Operating system have an environment for program execution. operating system provides several services for program and for the user of those program. Different operating systems provides different services but there are some common classes that can be identify. There are some operating system services. These services are provided for the ease of programmer to make the programing tasks easier. Below is some operating system services.
- Program execution
- File system manipulation
- I/O operations
- Resource allocation
- Error detection
The system must be capable to load the program into main memory for its execution. The program must be capable to end its execution.
File System Manipulation
It must be obvious that that program need to read and write the files, they also need to create and delete files by their names
A program may require I/O for its execution, these I/O can be a file or device. For specific device may be a specific function is required. For the concern of protection and efficiency user usually cannot directly control the I/O devices. Therefor operating system should provide some means to do I/O operations.
In many cases process need to exchange information with another process. This communication can occur in two major ways. First one tack places between processes executing on the same computer, second one take places between processes executing on the different computers that are connected via a computer network. Communication can be implemented using shared memory or by message passing technique in which packets of information are moved between processes by the operating system.
Whenever jobs are running simultaneously resources must be allocated to each of them. Operating system manages various types of resources. Some of them may requires special allocation codes whereas others such as I/O devices may have much more release codes or general request. To determine the efficiency of CPU, the operating system have CPU scheduling routines that take in to account the speed of the CPU, the jobs must be executed, the numbers of registers and other aspects. Retunes can be used to allocate the tape drive, plotters, modems and other peripheral devices. There is also a routine to clear the table on tape drive.
The operating system is constantly required to be aware of possible errors. The errors can occur in memory, CPU, I/O devices or in the user program. Operating system must take the proper action to ensure correct and reliable computing against each type of error.
keeping the track of which user use how much and what kind of computer resources, this record keeping may be for accumulating usage statistics or for simply accounting.
Protection concerns with ensuring that all access to system resources is controlled. Outside security of the system is also important. Such kind of security starts with each and every user having to authenticate himself or herself to the system, by the means of passwords to be provide access to the resources. It extends to protecting peripheral I/O devices with network adapters and modems from individual access attempts and to recording all these connections for detection of break-in. For protection and security of system persecution must be established through it.