Purpose of system calls in an operating system

Operating systems questions and answers, OS University exam questions, write down the purpose of systems calls in OS

Question:

Explain the purpose of system calls in an operating system with an example.

 

Answer:

System calls allow user processes to request service from the kernel. In particular, they allow the user to ask the kernel to do something for the user process that is not allowed to do for itself because of protection or sharing concerns. In simple terms, system calls are the programming interface to the services provided by the operation system.

Example:

User processes are allowed to access some files but not others, and have read access to some file and read/write access to others. Thus the write () system call allows a user process to ask the operating system to write some data to a file. Before performing the operation, the OS verifies that the user has write access for that file.

In addition, the system calls abstract away the details of the hardware and the lower level software, providing a clean, uniform, and portable application programming interface to the user processes.

 

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