5 - System Calls

Question 1

Does the shell or GUI or command line do the interpreting of the commands? Comment on answer.

Answer 1

No, it just finds a file that matches the name and if it is an executable, it executes it. The file contains the instructions that carry out the actual “command”.

Question 2

What does API stand for:

Answer 2

Application Programmer Interface.

Question 3

Describe API’s

Answer 3

Programmers call a function (system function) in a library which invokes system calls. The programmer only needs to understand the system function by understanding its parameters and results.

Question 4

What are system call codes a part of?

Answer 4

Part of the kernel.

Question 5

What is a standard for System Calls and Library Procedure Calls?

Answer 5

POSIX, an interface implemented by many different operating systems.

Question 6

Why not access the system calls directly?

Answer 6

Program portability. Also, actual system calls may be more detailed and more difficult to work with.