If the ifconfig command does not show the IPv4 address of a network interface on your Linux system, it could be because the interface is not configured to use IPv4.
To check the status of a network interface and its configured addresses, you can use the ip command with the addr option.
Here's an example of how you can use the ip command to display the IPv4 address of a network interface:
ip addr show interface_name | grep inet
Replace interface_name with the name of your network interface, such as eth0 or wlan0.
This command will display the IPv4 address and subnet mask of the interface, as well as the status of the interface (up or down).
If the interface is not configured to use IPv4, you will not see any output from this command.
To configure an interface to use IPv4, you can use the ip command with the addr and add options. For example:
ip addr add IP_ADDRESS/SUBNET_MASK dev interface_name
Replace IP_ADDRESS with the desired IPv4 address for the interface, and SUBNET_MASK with the appropriate subnet mask.
Keep in mind that this configuration will not be persisted after a reboot. To make the configuration permanent, you will need to add the ip command to a startup script or modify the interface configuration file in the /etc/network directory.
For more information about the ip command and its available options, you can consult the ip man page or use the ip --help command.