Hi Aitor!
Anno domini 2019 Tue, 19 Mar 09:56:07 +0100
aitor_czr scripsit:
> 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...
Interestingly the "carrier"-column in /proc/net/dev does not correspond to the
cable beeing plugged in or not, it's always "0" on my computer.
Nik
> 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,
>
> Aitor.
--
Please do not email me anything that you are not comfortable also sharing with
the NSA, CIA ...
_______________________________________________
Dng mailing list
Dng@lists.dyne.org
https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
