Linux进程编程demo2创建进程函数fork的使用.c

#include <stdio.h>
#include <unistd.h>
int main()
{
	
	pid_t pid;
	pid_t pid2;
	
	pid = getpid();//获取当前程序的pid
	printf("before fork:pid = %d\n",pid);
	
	fork();//在当前程序里fork一个新进程 
	//fork ()之后下面的代码会被执行两次 一次主进程 一次子进程
	pid2 = getpid();
	printf("after fork:pid = %d\n",pid2);
	
	if(pid == pid2){
		printf("this is father printf\n");
	}else{
		printf("this is child print,child pid =%d\n",getpid());
	}
	
	return 0;
}
//通过fork()的返回值判断父子进程

#include <stdio.h>
#include <unistd.h>
int main()
{
	pid_t pid;
	printf("father pid:%d\n",getpid());
	
	pid = fork();//fork()返回0代表当前是子进程   返回非负数代表当前是父进程
	
	if(pid>0){
		printf("this is father print,father pid:%d\n",getpid());
	}
	else if(pid == 0){
		printf("this is child print,child pid =%d\n",getpid());
	}
	return 0;
}```