How to detect the physical connected state of a network cable/connector?

Question

In a Linux environment, I need to detect the physical connected or disconnected state of an RJ45 connector to its socket. Preferably using BASH scripting only.

The

Answer 1

You can use ifconfig.

# ifconfig eth0 up
# ifconfig eth0

If the entry shows RUNNING, the interface is physically connected. This will be shown regardless if the interface is configured.

This is just another way to get the information in /sys/class/net/eth0/operstate.