问题log

/tmp/ccByifPx.o: In function `main':
read.c:(.text+0x1a): undefined reference to `shm_open'
read.c:(.text+0xd9): undefined reference to `shm_unlink'
collect2: error: ld returned 1 exit status

程序代码

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <unistd.h>

#define SHM_NAME "./mac_shm"
#define SHM_SIZE 18  // MAC地址长度为17个字符，加上一个终止符

int main() {
    // 打开共享内存对象
    int shm_fd = shm_open(SHM_NAME, O_RDONLY, 0666);
    if (shm_fd == -1) {
        perror("shm_open");
        exit(EXIT_FAILURE);
    }

    // 映射共享内存
    char *shm_ptr = mmap(0, SHM_SIZE, PROT_READ, MAP_SHARED, shm_fd, 0);
    if (shm_ptr == MAP_FAILED) {
        perror("mmap");
        exit(EXIT_FAILURE);
    }

    // 读取MAC地址
    printf("MAC Address: %s\n", shm_ptr);

    // 解除映射
    if (munmap(shm_ptr, SHM_SIZE) == -1) {
        perror("munmap");
        exit(EXIT_FAILURE);
    }

    // 关闭共享内存对象
    close(shm_fd);

    // 删除共享内存对象
    shm_unlink(SHM_NAME);

    return 0;
}

问题分析

编译结果实际上是说，没include相应的头文件，或是头文件不存在，man shm_open看到如下内容

解决方案

gcc shm_test.c -lrt -o shm_test