fork test

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <fcntl.h>

#include <stdio.h>

int global = 10;

int main() {

    int local = 5;

    pid_t pid;

    if ((pid = fork()) == 0) {

        global++; local++;

    } else {

        sleep(1);

    }

    printf("pid : %d, global:%d, local: %d\n", getpid(), global, local);

    return 0 ;

}

child process share the memory space of parent. when the write operation is occurred, the child copy memory space of parent.              

root@jcjung:/work# ./fork_test 

pid : 2018, global:11, local: 6

pid : 2017, global:10, local: 5