DEBIAN

NETWORKING NETWORKING

CONFIGURE IP IN UBUNTU

How to check the physical cable if it's alive.

$ sudo ethtool eth0

or

$ sudo ethtool eth0 | grep Link Link detected: yes

Alternative:

To work around using script.

You could try this:

gw="$(ip route | awk "/^default via/ {print \$3}")" ping -c 1 "$gw" > /dev/null result="$?"

Options option:

use this command to check a wire is connected:

cd /sys/class/net/ grep "" eth0/operstate

If the result will be up or down. Sometimes it shows unknown, then you need to check

eth0/carrier

It shows 0 or 1

cat /sys/class/net/ethX is by far the easiest method.

The interface has to be up though, else you will get an invalid argument error.

So first:

ifconfig ethX up

Then:

cat /sys/class/net/ethX

some ways, including ifconfig|grep RUNNING, ethtool, cat /sys/class/net/eth0/carrier, but all they require that the interface is up.