Question

I wrote a program

#include <stdio.h>
#include <unistd.h>

int main()
{
    int returnVal = fork();
    printf("Return Value: %i\n", returnVal);
    return 1;
}

when I compile this and run, I get the following output
I have given only one printf statement then why do I see 2 prints. If I remove the print then nothing is printed.

alwin@alwin-desktop:~/Projects/Nix$ ./a.out 
Return Value: 5547
Return Value: 0

Answer 1

You need to go through man command 🙂

Check: pid_t fork(void);

The fork() creates a new process by duplicating the calling process. The new process, referred to as the child, is an exact duplicate of the calling process, referred to as the parent.

DETAILS:: First you executed your code which created a child process. Now you have two processes executing the same piece of code. So TWO print statements, first of the Parent Process and second of the Child Process.