How to check the physical connection of a network card in CentOS 7?

To check the physical connection of the network card on CentOS 7, you can use the following command:

1. Open the terminal and log in as the root user or use the sudo command to obtain administrator privileges.
2. Run one of the following commands to check the physical connection status of the network interface:
3. Use the command ip link show.
4. Use the ifconfig command: ifconfig -a
5. These commands will display all network interfaces and their statuses in the system.
6. Look for the network interface card that interests you in the output, usually starting with “eth” or “en”, such as eth0 or enp0s3.
7. Check the status of the interface. If the status is “UP”, it means the physical connection is functioning properly. If the status is “DOWN”, it means the physical connection is disconnected.
8. Find the interface you are interested in the output, and check the value of the “state” field. If the value is “UP,” it means the physical connection is normal; if the value is “DOWN,” it means the physical connection is disconnected.
9. For example, when using the ip command, you can locate the interface you are interested in and check the value of the “state” field, as shown below:
10. eth0 is enabled, can send and receive data, and has a maximum transmission unit of 1500.
11. When using the ifconfig command, you can locate the interface you are interested in and look for the “UP” or “DOWN” flags as shown below:
12. eth0: interface is currently active, broadcasting, running, and capable of receiving multiple transmissions, with a maximum transmission unit size of 1500.

This way, you can use these commands to check the physical connection status of the network card on CentOS 7.