Linux--setsid函数

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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

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