Ubuntu: wait for network link up and execute a bash command

Question

In Ubuntu (the latest distro is fine), I want to reboot a router and inside a bash script I\'d like to have a command that waits for the network link to be up again and, whe

Answer 1

If you want a command to check if the link is up or down use ip :

ip addr show eth0 | grep -Po "(?<=state ).*?(?=\s)"
DOWN

ip addr show wlan0 | grep -Po "(?<=state ).*?(?=\s)"
UP