Linux--setsid函数

调用setsid函数的进程需要满足以下条件：

1. 不是组长进程

2. 有对应的创建session权限

调用setsid函数后的进程：

1. 成为一个组的组长进程

2. 成为一个会话的会话首进程

3. 放弃了控制终端

#include <stdio.h>#include <unistd.h>#include <stdlib.h>int main(int argc, char *argv[]){	pid_t pid;		pid = fork();		if (pid < 0)	{		perror("fork");		return -1;	}	else if (pid == 0)	{		PRintf("before====/n");		printf("pid = %d/n", (int)getpid());		printf("gid = %d/n", (int)getpgrp());		printf("sid = %d/n", (int)getsid(getpid()));				setsid();				printf("after====/n");		printf("pid = %d/n", (int)getpid());		printf("gid = %d/n", (int)getpgrp());		printf("sid = %d/n", (int)getsid(getpid()));				sleep(5);	}	else	{		printf("parent-------/n");		printf("pid = %d/n", getpid());		printf("gid = %d/n", getgid());		printf("sid = %d/n", getsid());		waitpid(pid, NULL, 0);	}		return 0;}运行结果：
parent-------pid = 13227gid = 0sid = 12710before====pid = 13228gid = 13227sid = 12710after====pid = 13228gid = 13228sid = 13228