Coupon Accepted Successfully!


System Calls

System calls provide for a bridge between the process 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. These calls are usually available as routines written in C and C++.
System calls can be broadly classified into five categories viz.

1. Process Control

2. File Management/Manipulation

3. Device Management/Manipulation

4. Information Maintenance

5. Communications

Type of System Call Example

Process Control
1. End, abort(abort)

2. Load, execute(exec)

3. Create process(fork)

4. Terminate process(exit)

5. Wait for time (wait time/ event)

File Management
1. Create files (create fileA)
2. Delete files(delete fileA)
3. Open files
4. Close files
5. Read/Write files

Device Management
1. Request device
2. Release device
3. Read/Write on device

Information Maintenance
1. Get time (time)
2. Get date (date)
3. Get system version
4. Get user count
1. Create connection
2. Delete connection
3. Send/Receive messages
4. Status information

Each system call needs name of file and often some attributes of the file. A file is first created, opened, read/written and closed or deleted thereafter.

A process can often require other devices to function properly, such as disk drives. If these are not available, process will have to wait. We first request device. Once device is allocated to us, we can read/write on device just as with files. After we are done, we release it for use by other processes.
These system calls are used for transferring information between user program and OS. They may also be used to return number of users, system version, free disk space etc.
Before communication takes place between processes, communication has to be made. For inter-process communication, we may use Shared Memory model or Message passing model.

Test Your Skills Now!
Take a Quiz now
Reviewer Name