IT628: Systems Programming - Process Creation

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Questions and Answers

What is the basic unit of execution in an OS?

A process

What are the main categories of system calls?

File system, multi-tasking mechanisms, inter-process communication

What is the purpose of a "fork()" system call?

To create a new process that is a copy of the calling process.

What differentiates a program from a process?

A program is a static file or set of instructions, while a process is the dynamic execution context of a program. Signup and view all the answers

What does a context switch involve?

Saving the state of the current process and restoring the state of another process before passing control Signup and view all the answers

What value does the 'fork()' function return in the child process?

0 (zero) Signup and view all the answers

What happens when a process calls 'fork()'?

The program is copied and loaded in a new memory space, creating a separate process Signup and view all the answers

In the following code snippet, how many "Hello world!" messages will be printed to the console? `c int main() { fork(); printf("Hello world!\n"); }`

2 Signup and view all the answers

What is the key advantage of using the `fork()` system call?

Creating multiple processes without having to reload the same program code for each process Signup and view all the answers

The 'fork()' system call guarantees that the child process will always be created before the parent process continues execution.

False Signup and view all the answers

The 'fork()' system call allows for the creation of multiple child processes within a single parent process.

True Signup and view all the answers

What is the purpose of the 'exec()' system call?

To replace the current running process with a new program. Signup and view all the answers

Match the following system calls with their primary function:

<code>fork()</code> = Creates a new process that is a copy of the calling process <code>exec()</code> = Replaces the current process with a new program <code>wait()</code> = Suspends the calling process until a child process terminates <code>exit()</code> = Terminates the calling process <code>signal()</code> = Sends a signal to a process <code>kill()</code> = Sends a signal to a process, often used for termination Signup and view all the answers

The 'strcpy()' system call is used to copy data between two processes.

False Signup and view all the answers

The 'pipe()' system call is used to create a pipe between two processes.

True Signup and view all the answers

What is the role of the operating system when multiple processes run concurrently?

The operating system manages the shared resources, schedules the processes, and ensures that they do not interfere with each other. Signup and view all the answers

What is the primary purpose of concurrent programming?

To leverage multiple processors or cores to improve the efficiency and performance of applications by performing tasks in parallel. Signup and view all the answers

All processes running on a single system must have unique process identifiers (PIDs).

True Signup and view all the answers

The 'fork()' system call can create a child process with a different program code from the parent process.

False Signup and view all the answers

When a process is terminated by the system, its PID is always immediately released for reuse by a new process.

False Signup and view all the answers

The 'fork()' system call is the only mechanism for creating a new process.

False Signup and view all the answers

The `fork()` function creates a copy of the current process' entire memory space.

True Signup and view all the answers

The 'fork()' and 'exec()' system calls are interchangeable and can be used to accomplish the same goal

False Signup and view all the answers

What is the typical return value of a successful `fork()` call in the parent process?

The process identifier (PID) of the newly created child process Signup and view all the answers

Explain why the 'fork()' system call is essential for concurrent programming.

The 'fork()' system call is essential for concurrent programming because it allows the creation of multiple processes that can execute concurrently, enabling parallel processing of tasks and improving the overall performance and efficiency of applications. Signup and view all the answers

It is advisable to use `fork()` system call to create many processes within a loop, for performing a repetitive task.

False Signup and view all the answers

How do you determine which process is the parent and which is the child after a 'fork()' call?

The parent process can identify itself via the return value of 'fork()' which will be a non-zero PID. The child process, on the other hand, will receive a return value of 0. Signup and view all the answers

Study Notes

Course Outline and Process Creation

Course name: IT628: Systems Programming
Course focus: System Programming, process creation

Course Description

Operating systems (OS) provide constructs and primitives to simplify application development.
Students will learn to write applications leveraging important OS features.
Lessons often present an OS concept followed by associated system calls.

Main Topics

Concurrent programming: Processes, signals, pipes, threads, and synchronization.
Network programming: Sockets and servers.

System Calls

System calls: Requests to the OS to perform actions on behalf of the user program.
Examples include: fork() (creating child processes), exec() (executing programs), and various file system calls (e.g., creat, open, read, write, Iseek, close).
System calls are distinct from libc calls (e.g., strcpy).

Categories of System Calls

File system: Low-level file I/O operations such as creat, open, read, write, Iseek, and close.
Multi-tasking mechanisms: Process control, including operations such as fork, wait, exec, exit, signal, and kill.
Inter-process communication: Methods such as pipe, dup, and dup2.

Classroom Organization

Lectures, exercises, and code demos will make up the classes.
Students are encouraged to ask questions.

Classroom Etiquette

Punctuality is expected.
Talking and cell phone use will not be tolerated.

Reference Books

Keith Haviland, Dina Gray, and Ben Salama: "UNIX System Programming" (Addison-Wesley)
Randal Bryant and David O'Hallaron: "Computer Systems: A Programmer's Perspective" (Pearson India)
Brian Kernighan and Dennis Ritchie: "The C Programming Language, Second Edition" (Prentice Hall India)

Grade Breakdown

Exams (70%): Two in-semester exams and a final exam (in-semester exams weighted 20%, final exam weighted 50%).
Lab exercises and homework (30%): Weighted 20% for checkoffs and 10% for other homework assignments. -Lab attendance is mandatory.

Processes

A process is a basic unit of execution within an OS.
A process is a running instance of a program.
A program represents a static file (image).
A process includes a program and its execution state.
Concurrent processes involve interleaved instructions.

Context Switching

Context switch: Transferring control from one process to another.
OS saves the current process's state and loads the next process's state.
From a user perspective, multiple processes appear simultaneous.

`fork()` System Call

fork() creates a new process.
The newly created (child) process runs the same program as the original (parent) process with the same CPU registers and open files.

`fork()` Return Value

fork() returns a unique process identifier (pid_t).
- Child receives 0.
- Parent receives the child's pid.

Example `fork()` code and outputs

Demonstrates both parent and child process outputs after fork operation.
- Shows various possible outcomes with different fork() calls.

`fork()` Practice Problems

Several code examples demonstrate how fork() works. -Provides output examples and possible outcomes relevant to the code.

Additional Notes

The order of execution is non-deterministic after a fork.
Post-fork, parent and child are separate processes but initially identical.
OSs separately manage the data and states of parent and child processes.
Control flow may diverge following the fork operation.
Illustrates how fork() creates multiple processes.

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Description

Explore the fundamentals of systems programming in IT628, focusing on process creation and system calls. This quiz covers key concepts such as concurrent programming, OS features, and examples like fork() and exec(). Test your understanding of system calls and their role in application development.

IT628: Systems Programming - Process Creation

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Questions and Answers

What is the basic unit of execution in an OS?

What are the main categories of system calls?

What is the purpose of a "fork()" system call?

What differentiates a program from a process?

What does a context switch involve?

What value does the 'fork()' function return in the child process?

What happens when a process calls 'fork()'?

In the following code snippet, how many "Hello world!" messages will be printed to the console? c int main() { fork(); printf("Hello world!\n"); }

What is the key advantage of using the fork() system call?

The 'fork()' system call guarantees that the child process will always be created before the parent process continues execution.

The 'fork()' system call allows for the creation of multiple child processes within a single parent process.

What is the purpose of the 'exec()' system call?

Match the following system calls with their primary function:

The 'strcpy()' system call is used to copy data between two processes.

The 'pipe()' system call is used to create a pipe between two processes.

What is the role of the operating system when multiple processes run concurrently?

What is the primary purpose of concurrent programming?

All processes running on a single system must have unique process identifiers (PIDs).

The 'fork()' system call can create a child process with a different program code from the parent process.

When a process is terminated by the system, its PID is always immediately released for reuse by a new process.

The 'fork()' system call is the only mechanism for creating a new process.

The fork() function creates a copy of the current process' entire memory space.

The 'fork()' and 'exec()' system calls are interchangeable and can be used to accomplish the same goal

What is the typical return value of a successful fork() call in the parent process?

Explain why the 'fork()' system call is essential for concurrent programming.

It is advisable to use fork() system call to create many processes within a loop, for performing a repetitive task.

How do you determine which process is the parent and which is the child after a 'fork()' call?

Study Notes

Course Outline and Process Creation

Course Description

Main Topics

System Calls

Categories of System Calls

Classroom Organization

Classroom Etiquette

Reference Books

Grade Breakdown

Processes

Context Switching

fork() System Call

fork() Return Value

Example fork() code and outputs

fork() Practice Problems

Additional Notes

Studying That Suits You

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In the following code snippet, how many "Hello world!" messages will be printed to the console? `c int main() { fork(); printf("Hello world!\n"); }`

What is the key advantage of using the `fork()` system call?

The `fork()` function creates a copy of the current process' entire memory space.

What is the typical return value of a successful `fork()` call in the parent process?

It is advisable to use `fork()` system call to create many processes within a loop, for performing a repetitive task.

`fork()` System Call

`fork()` Return Value

Example `fork()` code and outputs

`fork()` Practice Problems