Fork() System Call

It is used to create or generate a child process. So, The purpose of fork() is to create a new process, which becomes the child process of the caller. It takes no arguments and returns a process ID.

1. fork() returns a zero to the newly created child process

2. fork() returns a positive value,to the parent process

3. If fork() returns a negative value, the creation of a child process was unsuccessful.

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For example:

1)

int main() 
{ 
 fork(); 
 printf("Hello!\n"); 
 return 0; 
}

Output:
Hello!
Hello!

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2)

int main() 
{ 
    fork(); 
    fork(); 
    fork(); 
    printf("hello\n"); 
    return 0; 
} 

Output:
hello
hello
hello
hello
hello
hello
hello
hello

The number of times ‘hello’ is printed is equal to the number of processes created. Total Number of Processes = 2^n, where n is the number of fork system calls. So here n = 3, 2^3 = 8.So there are a total of eight processes (new child processes and one original process).

The total number of child processes created is 2^n-1. So, 2^3-1 is 7.

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Happy Coding!

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