linux process study (very easy to know)

Today, I want to learn how to write a program using the multi-process! now, I will show a very easy Ex for you to study! here are the codes! //parent process "process.c" #include #include void main(int argc, char *argv[]){ int pid; pid = fork(); printf("pid =%d\n", pid); if(pid < 0){ printf("Error:Cant creat a new process!\n"); } else if(pid == 0){ execlp("/home/daniel/Desktop/hw1/compare",NULL,NULL); } else{ wait(NULL); printf("Succeed:Child Complete!\n"); } return ; } //child process "compare.c" #include void main(void){ /*compare 3 and 5, which one is bigger*/ printf("You are running the child process!\n"); int i=3,j=5; printf("i=%d ,j=%d.\n",i,j); if(i > j){ printf("OK, %d > %d!\n",i,j); } else{ printf("OK, %d < %d!\n",i,j); } return ; } When you type the code into your vim, save it and using the gcc to compile it ! for Ex: gcc -W compare.c -o compare after you compile the program , you will find you can run the process ,and it can call the campare program to run.