Linux下如何用C编程实现检测网卡与网线的连接状态

int get_netportstatus(const char *interface) {
  char cmd[1024];
  char *tt;
  FILE *fp;
  int devflag;
  devflag=get_netflag(interface);
  if (devflag==DEV_DOWN) {
    sprintf(cmd,"ifconfig %s up",interface);
    system(cmd);
  }
  sprintf(cmd,"ethtool %s | grep "Link detected" > /tmp/eth.temp",interface);
  system(cmd);
  if (devflag==DEV_DOWN) {
    sprintf(cmd,"ifconfig %s down",interface);
    system(cmd);
  }
  fp=fopen("/tmp/eth.temp","r");
  if (fp==NULL) {
    system("rm -rf /tmp/eth.temp");
    return -1;
  }
  fgets(cmd,1024,fp);
  fclose(fp);
  system("rm -rf /tmp/eth.temp");
  tt=strstr(cmd,"no");
  if (tt!=NULL) return LINK_DOWN;
  tt=strstr(cmd,"yes");
  if (tt!=NULL) return LINK_UP;
  return -1;
}

用c/c++实现linux下检测网络接口状态

#include 
#include 
#include 
#include 
#include 
#include 
#include 


struct ethtool_value {
        __uint32_t      cmd;
        __uint32_t      data;
};


int main(int , char* [])
{
    struct ethtool_value edata;
    int fd = -1, err = 0;
    struct ifreq ifr;


        memset(&ifr, 0, sizeof(ifr));
        strcpy(ifr.ifr_name, "eth0");
        fd = socket(AF_INET, SOCK_DGRAM, 0);
        if (fd < 0) {
                perror("Cannot get control socket");
                return 70;
        }


        edata.cmd = 0x0000000a;
        ifr.ifr_data = (caddr_t)&edata;
        err = ioctl(fd, 0x8946, &ifr);
        if (err == 0) {
                fprintf(stdout, "Link detected: %sn",
                        edata.data ? "yes":"no");
        } else if (errno != EOPNOTSUPP) {
                perror("Cannot get link status");
        }
   return 0;
}

#include   // IFF_RUNNING

//如果网卡已脸上网线，返回0，否则返回-1.
int check_nic(char *nic)
{
    struct ifreq ifr;
    int skfd = socket(AF_INET, SOCK_DGRAM, 0);

    strcpy(ifr.ifr_name, nic_name);
    if (ioctl(skfd, SIOCGIFFLAGS, &ifr) < 0)
    {
        return -1;
    }
    if(ifr.ifr_flags & IFF_RUNNING)
        return 0;  // 网卡已插上网线
    else return -1;
}