linux查看网卡是否连接

编程部分转自http://topic.csdn.net/u/20100920/16/7D58E76F-39FE-44B3-B4AC-D65D5AE57D2D.html

以前知道通过ethtool可以查看网卡是否已连接。编程实现如下：

#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <errno.h>
#include <net/if.h>
struct ethtool_value {
__uint32_t      cmd;
__uint32_t      data;
};
int main(int argc, char* argv[])
{
struct ethtool_value edata;
int fd = -1, err = 0;
struct ifreq ifr;
memset(&ifr, 0, sizeof(ifr));
strcpy(ifr.ifr_name, argv[1]);
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: %s/n", edata.data ? "yes":"no");
}
else if (errno != EOPNOTSUPP){
perror("Cannot get link status");
}
return 0;
}

以上代码在Linux MagicLinux 2.6.18-92.el5 #1 SMP Tue Apr 29 13:16:12 EDT 2008 i686 i686 i386 GNU/Linux环境编译通过