1. Brief about the initial process sequence while the system boots up.
While booting, special process called the 'swapper' or 'scheduler' is created with Process- ID 0. The swapper manages memory allocation for processes and influences CPU allocation. The swapper inturn creates 3 children:
This is done by executing the file "/etc/init". Process dispatcher gives birth to the shell. Unix keeps track of all the processes in an internal data structure called the Process Table (listing command is ps -el).
2. What are various IDs associated with a process?
Unix identifies each process with a unique integer called ProcessID. The process that executes the request for creation of a process is called the 'parent process' whose PID is 'Parent Process ID'. Every process is associated with a particular user called the 'owner' who has privileges over the process. The identification for the user is 'UserID'. Owner is the user who executes the process. Process also has 'Effective User ID' which determines the access privileges for accessing resources like files.
3. Explain fork() system call.
The 'fork()' used to create a new process from an existing process. The new process is called the child process, and the existing process is called the parent. We can tell which is which by checking the return value from 'fork()'. The parent gets the child's pid returned to him, but the child gets 0 returned to him.
4. Predict the output of the following program code.
Answer: Hello World!Hello World!
5. Predict the output of the following program code
Answer: "Hello World" will be printed 8 times.
6. List the system calls used for process management:
System calls - Description