Get link speed programmatically?
You need to use the SIOCETHTOOL ioctl() call. There's a nice introduction to ioctl/SIOCETHTOOL call on LinuxJournal, and the code below (which is not intended to be an example of good C practices!) should show you how to use it to get the speed.
#include <stdio.h>#include <sys/socket.h>#include <sys/ioctl.h>#include <netinet/in.h>#include <linux/sockios.h>#include <linux/if.h>#include <linux/ethtool.h>#include <string.h>#include <stdlib.h>int main (int argc, char **argv){ int sock; struct ifreq ifr; struct ethtool_cmd edata; int rc; sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); if (sock < 0) { perror("socket"); exit(1); } strncpy(ifr.ifr_name, "eth0", sizeof(ifr.ifr_name)); ifr.ifr_data = &edata; edata.cmd = ETHTOOL_GSET; rc = ioctl(sock, SIOCETHTOOL, &ifr); if (rc < 0) { perror("ioctl"); exit(1); } switch (ethtool_cmd_speed(&edata)) { case SPEED_10: printf("10Mbps\n"); break; case SPEED_100: printf("100Mbps\n"); break; case SPEED_1000: printf("1Gbps\n"); break; case SPEED_2500: printf("2.5Gbps\n"); break; case SPEED_10000: printf("10Gbps\n"); break; default: printf("Speed returned is %d\n", edata.speed); } return (0);}