Fork()


 
Thread Tools Search this Thread
Top Forums Programming Fork()
# 1  
Old 01-12-2010
Fork()

does fork() spawn only the parent process, what if fork() is looped, does it spawn the parent and the child?
# 2  
Old 01-12-2010
fork forks a process, so the process which called fork is parent, and which got forked is child.

when you have a loop, then the child will again call fork, by which it will become parent of another process which gets forked by the fork.

Finally, not only forking is possible in parent. any process can call fork, and it gets a child process forked for it.

If this does not explains you what you wanted, then make the question more clear please.
# 3  
Old 01-12-2010
you've answered 50% of it, if a parent is forked, then fork is called again, will both the parent and the child be forked or only the child, in other words will both of them be forking in parallel?

fork()
PID1 -> PID2
then fork() again
PID1->PID3
PID2->PID4
?
# 4  
Old 01-13-2010
Yes, you are right.

An example to clarify the matter better,

Code:
use strict;
use warnings;

print "PARENT 1: $$\n";
my $pid = fork ();
if ( $pid )  {
    print "Parent of 1st fork $$\n";
} else {
    print "Child of 1st fork $$\n";
}

my $next_pid = fork ();

if ( $next_pid )  {
    print "Parent of next fork $$\n";
} else {
    print "Child of next fork $$\n";
}

And its output,
Code:
PARENT 1: 27844
Child of 1st fork 27845
Child of next fork 27846
Parent of next fork 27845
Parent of 1st fork 27844
Child of next fork 27847
Parent of next fork 27844

It is so clear that, the first process id is: 27844, which gets forked into another as: 27845.

Then the next is two parents: 27844, 27845 which gets two childs as: 27846, 27847.
# 5  
Old 01-13-2010
now it's very clear and 100% answers my question, thanks.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Programming

Fork!

I understand that fork create a child but I need very simple example that make child useful.... I mean how will make the program faster anyone explain with code plz using C plz (2 Replies)
Discussion started by: fwrlfo
2 Replies

2. UNIX for Dummies Questions & Answers

fork()

I'm trying to run a simple test on how to use fork(), i'm able to execute the child process first then the parent, but how can I execute parent then child..? Thanks! (1 Reply)
Discussion started by: l flipboi l
1 Replies

3. Programming

Fork and \n

Hi, I wrote a simple program for understanding the fork command. The code is as below int main(void) { fork(); printf("hi 1 \n"); fork(); printf("hi 2 \n"); fork(); printf("hi 3 \n"); } I am getting a variation in the number of times the printf is called if i remove the \n from each... (2 Replies)
Discussion started by: xyz123456
2 Replies

4. UNIX for Advanced & Expert Users

Fork and \n

Hi, I wrote a simple program for understanding the fork command. The code is as below int main(void) { fork(); printf("hi 1 \n"); fork(); printf("hi 2 \n"); fork(); printf("hi 3 \n"); } I am getting a variation in the number of times the printf is called if i remove the \n from each of... (1 Reply)
Discussion started by: xyz123456
1 Replies

5. Programming

fork() help

Hi everybody, I wanna write a code to understand how fork works. my target -------------- -Parent creates a file(called temp) and writes into this file "1".Then it closes the file. -Then parent creates a child and wait until execution of this child ends. -Then child opens the same... (3 Replies)
Discussion started by: alexicopax
3 Replies

6. Programming

Fork ()

hi all About this code for (i = 1; i < n; i++) if ((childpid = fork()) <= 0) break; I really can't understand the output . and the way fork () return the value . how about the process Id ,the child process Id and the parent ID in this case so please answer me soon (5 Replies)
Discussion started by: iwbasts
5 Replies

7. Programming

Fork or what?

Hello all. I'm developing a filetransfer application, which is supposed to work sort of like dcc, with multiple transfers etc. Now i wonder what the best way to manage the transfers is. Should i fork() for each new transfer, hogging loads of memory or use pthreads? Maybe I can use select to see... (0 Replies)
Discussion started by: crippe
0 Replies

8. Programming

fork()

#include <stdio.h> #include <string.h> #include <sys/types.h> #define MAX_COUNT 200 #define BUF_SIZE 100 void main(void) { pid_t pid; int i; char buf; fork(); pid = getpid(); for (i = 1; i <= MAX_COUNT; i++) { sprintf(buf,... (2 Replies)
Discussion started by: MKSRaja
2 Replies

9. Programming

fork() fd

I run this code, actually I want to both processes print the message from "data". But only one does. What happens? Anyone can help? #include <stdio.h> main(){ int fd, pid; char x; fd = open("data",0); /* open file "data" */ pid = fork(); if(pid != 0){ wait(0); ... (2 Replies)
Discussion started by: Herman
2 Replies

10. UNIX for Dummies Questions & Answers

Fork

What is a fork? Why would one create a fork? What are the advantages and disadvantages of using a fork? Please advise. Thank You. Deepali (5 Replies)
Discussion started by: Deepali
5 Replies
Login or Register to Ask a Question