linux串口数据 读取

4. **关闭设备文件**：
```c
close(fd);

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <termios.h>

int main() {
    int fd = open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
        perror("open_port: Unable to open port");
        return -1;
    }

    struct termios options;
    tcgetattr(fd, &options);
    cfsetispeed(&options, B9600);
    options.c_cflag |= (CLOCAL | CREAD);
    options.c_cflag &= ~PARENB;
    options.c_cflag &= ~CSTOPB;
    options.c_cflag &= ~CSIZE;
    options.c_cflag |= CS8;
    tcsetattr(fd, TCSANOW, &options);

    char buffer[256];
    int n = read(fd, buffer, sizeof(buffer));
    if (n < 0) {
        perror("read failed");
    } else {
        printf("Read %d bytes: %s
", n, buffer);
    }

    close(fd);
    return 0;
}