google: linux bash does not recognize when network comes up

• use ping

  #!/bin/bash
      TARGET_HOST="8.8.8.8"
      while ! ping -c 1 "$TARGET_HOST" &> /dev/null; do
          echo "Waiting for network connectivity..."
          sleep 5 # Wait 5 seconds before retrying
      done
      echo "Network is up! Continuing with script..."
      # Your network-dependent commands here

• check network interface state

  #!/bin/bash
      INTERFACE="eth0" # Replace with your actual interface name
      while [[ $(</sys/class/net/${INTERFACE}/operstate) != "up" ]]; do
          echo "Waiting for interface $INTERFACE to be up..."
          sleep 5
      done
      echo "Interface $INTERFACE is up! Continuing with script..."
      # Your network-dependent commands here

google: linux interface up when no router

• HUAWEI-UPS2000(8)
• google “nut with qinheng electronics ch341”
• systemctl reload nut-server
• google “nut driver not connected”
• google “how to create driver for nut in debian 12”