在linux下用ioctl重新映射键盘

我正在测试这段代码：

#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <linux/input.h>
#include <string.h>
#include <stdio.h>

static const char *const evval[3] = {
    "RELEASED","PRESSED ","REPEATED"
};

int main(void)
{
    const char *dev = "/dev/input/event2";
    struct input_event ev;
    ssize_t n;
    int fd;
    char name[256]= "Unknown";

//    int codes[2];

//    codes[0] = 58; /* M keycap */
//    codes[1] = 49; /* assign to N */

    fd = open(dev,O_RDONLY);
    if (fd == -1) {
        fprintf(stderr,"Cannot open %s: %s.n",dev,strerror(errno));
        return EXIT_FAILURE;
    }

    if(ioctl(fd,EVIOCGNAME(sizeof(name)),name) > 0) 
    {
        printf("The device on %s says its name is '%s'n",name);
    }

    /*
    int err = ioctl(fd,EVIOCSKEYCODE,codes);
    if (err) {
        perror("evdev ioctl");
    }*/

    while (1) {
        n = read(fd,&ev,sizeof ev);
        if (n == (ssize_t)-1) {
            if (errno == EINTR)
                continue;
            else
                break;
        } else
        if (n != sizeof ev) {
            errno = EIO;
            break;
        }

        if (ev.type == EV_KEY && ev.value >= 0 && ev.value <= 2)
            printf("%s 0x%04x (%d)n",evval[ev.value],(int)ev.code,(int)ev.code);

    }

    fflush(stdout);
    fprintf(stderr,"%s.n",strerror(errno));

    return EXIT_FAILURE;
}

重点是我不知道如何通过其他方式更改某些输入密钥.我尝试通过更改事件代码调用当前红色事件上的write(),发送密钥仍然是前一个,我尝试使用带有EVIOCSKEYCODE的ioctl,但调用失败并出现“无效参数”错误(我不是一定要正确调用它.

如何正确更改输出密钥？