System Call:
System calls provide an interface between the processor and the operating system. System calls allow user-level processes to request some services from the operating system which process itself is not allowed to do. For example, for I/O a process involves a system call telling the operating system to read or write a particular area and this request is satisfied by the operating system.
The following different types of system calls provided by an operating system:-
Process control
- end, abort
- load, execute
- create a process, terminate the process
- get process attributes, set process attributes
- wait for time
- wait for the event, a signal event
- allocate and free memory
File management
- create a file, delete a file
- open, close
- read, write, reposition
- get file attributes, set file attributes
Device management
- request device, the release device
- read, write, reposition
- get device attributes, set device attributes
- logically attach or detach devices
Information maintenance
- get time or date, set time or date
- get system data, set system data
- get process, file, or device attributes
- a set process, file, or device attributes
Communications
- create, delete communication connection
- send, receive messages
- transfer status information
- attach or detach remote devices