fork_vars.c

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

/* Using Fork to spawn child processes & understanding how it works with variables scopes */
/* All variable get segregated - vars(locals & globals); Not text segments
 * Open file descriptors remain open if opened in the parent process -> can be closed in child
 * */

/* Global variables */
int GLOBAL1 = 10;
static int GLOBAL2 = 20;

int main()
{
    int local_process = 30;
    pid_t pid;

    if( (pid = fork()) > 0)
    {
        printf("Parent: initial value of GLOBAL1= %d\n", GLOBAL1);
        printf("Parent: initial value of static GLOBAL2=%d\n", GLOBAL2);
        printf("Parent: initial value of loval var=%d\n", local_process);
        GLOBAL1 = 11;
        GLOBAL2 = 21;
        local_process = 31;
        printf("Parent: modified value of GLOBAL1=%d\n", GLOBAL1);
        printf("Parent: modified value of static GLOBAL2=%d\n", GLOBAL2);
        printf("Parent: modified value of local var=%d\n", local_process);
    }
    else
    {
        printf("child: initial value of GLOBAL1=%d\n", GLOBAL1);	
		printf("child: initial value of static GLOBAL2=%d\n", GLOBAL2);	
		printf("child: initial value of local var=%d\n", local_process);	
		GLOBAL1 = 15;
		GLOBAL2 = 25;
		local_process = 35;
		printf("child: modified value of GLOBAL1=%d\n", GLOBAL1);	
		printf("child: modified value of static GLOBAL2=%d\n", GLOBAL2);	
		printf("child: modified value of local var=%d\n", local_process);	
    }

    sleep(1);
    return 0;
}