To set up a routing metric for a network device on a Red Hat or CentOS Linux system, you can use the ip command with the route subcommand and the metric option.
The routing metric is a value that is used by the routing algorithm to determine the best route for a packet. A lower metric value indicates a more preferred route.
For example, to set the metric for the eth0 device to 10, you can use the following command:
ip route add default via 192.168.1.1 dev eth0 metric 10
This will add a default route for the eth0 device with a metric of 10.
You can also use the route command to set the routing metric. For example:
route add default gw 192.168.1.1 dev eth0 metric 10
It's always a good idea to carefully review the documentation and use the appropriate commands to set the routing metric for your network devices. This can be useful in cases where you want to specify the order in which routes are preferred by the routing algorithm.