On 19/3/19 9:56, aitor_czr wrote:
>
> Hi Nick,
>
> On 19/3/19 9:21, Dr. Nikolaus Klepp wrote:
>> You might call me ignorant, but with bash this can be done a bit simpler (this is from my solution to the detect-if-kable-present-while-booting-problem):-)
>>
>> #!/bin/bash
>>

>> while sleep 1; do
>>      for i in /sys/class/net/eth*; do
>>          VAR=$(basename $i)
>>          VAL=$(sed -n 's/0/UN/p' $i/carrier)PLUGGED
>>          if [ "${!VAR}" != "$VAL" ]; then
>>              echo $VAR $VAL
>>              declare $VAR=$VAL
>>          fi
>>      done
>> done

>>
>>
>> Nik
> Thanks for your script! Interesting to know... With a short look, i
> seems to read the value content in the /sys/class/eth0/carrier file,
> set to "0" or "1".
> I was thinking about this possibility a couple of days ago, but i'm
> not pretty sure if its value also depends on the status of the network
> hotpluggable device. I'm testing it...
> On the other hand, here you are the code used in the ethtool-lite.c
> file of the netcfg udeb package used by debian-installer, doing
> something similar (in the case of the FreeBSD kernel
> it uses a raw socket instead):
>
>     int len = strlen(SYSCLASSNET) + strlen(iface) + strlen("/carrier")
> + 1;
>     char* filename = malloc(len);
>     snprintf(filename, len, SYSCLASSNET "%s/carrier", iface);
>     FILE* fp = fopen(filename, "r");
>     free(filename);
>
>     char result[2];
>     if (fgets(result, sizeof(result), fp) == NULL) {
>         fclose(fp);
>         if (errno == EINVAL) {
>             di_info("ethtool-lite: %s is down", iface);
>             return DISCONNECTED;
>         }
>         di_error("ethtool-lite: getting carrier failed: %s",
>             strerror(errno));
>         return UNKNOWN;
>     }
>     fclose(fp);
>
>     switch (result[0]) {
>     case '1':
>         di_info("ethtool-lite: %s: carrier up", iface);
>         return CONNECTED;
>     case '0':
>         di_info("ethtool-lite: %s: carrier down", iface);
>         return DISCONNECTED;
>     }
>     di_info("ethtool-lite: %s: could not determine carrier state; got
> \"%s\"",
>         iface, result);
>     return UNKNOWN;
>
> Cheers,
>
#if defined(__linux__)

    /* The above code */

#elif defined(__FreeBSD_kernel__)
    int fd = socket(AF_INET, SOCK_DGRAM, 0);

    if (fd < 0)
    {
        di_warning("ethtool-lite: could not open control socket\n");
        return UNKNOWN;

    }