#include <unistd.h>
#include <linux/reboot.h>


int main() {
    reboot(LINUX_REBOOT_MAGIC1,LINUX_REBOOT_MAGIC2,LINUX_REBOOT_CMD_POWER_OFF,0);
    //   sync();
    //    reboot(LINUX_REBOOT_CMD_POWER_OFF);
}
Of course,you will need sufficient privileges to use this syscall.
必须有root权限哦