使用getuid和geteuid函数判断程序是否以root用户启动,同时dup2函数屏蔽所有错误信息

#include <stdio.h>
#include <fcntl.h>
int main(void)
{
    if (getuid() == 0 || geteuid() == 0) {
        int fd0 = open("/dev/null", O_RDWR);
        int fd1 = open("/dev/null", O_RDWR);
        int fd2 = open("/dev/null", O_RDWR);
        dup2(1, fd1);
        dup2(2, fd2);
        dup2(fd0, 1);
        dup2(fd0, 2);
        int ret = system("rmmod pl2303");
        dup2(fd1, 1);
        dup2(fd2, 2);
        close(fd0);
        close(fd1);
        close(fd2);
        printf("Good, root user\n");
    } else {
        printf("Please run luther.gliethttp in root user\n");
        return -1;
    }

    return 0;
}

luther@gliethttp:/vobs/tmp$ gcc getuid_geteuid.c
luther@gliethttp:/vobs/tmp$ ./a.out
Please run luther.gliethttp in root user
luther@gliethttp:/vobs/tmp$ sudo ./a.out
Good, root user