How to use the command nmcli device (with examples)

The nmcli device command is used to manage network interfaces and establish new Wi-Fi connections using NetworkManager. It provides various options and can be useful for network configuration and troubleshooting.

Use case 1: Print the statuses of all network interfaces

Code:

nmcli device status

Motivation: This use case is helpful when you want to quickly check the status of all network interfaces on your system. It provides information about whether a network interface is connected, the IP address assigned, and other relevant details.

Explanation: The status argument is provided to the nmcli device command to specify the task of printing the statuses of all network interfaces.

Example output:

DEVICE          TYPE      STATE         CONNECTION
eth0            ethernet  connected     Wired connection 1
wlan0           wifi      disconnected  --
lo              loopback  unmanaged     --

In the example output, you can see the names of the devices (eth0, wlan0, and lo), their types (ethernet, wifi, and loopback), their connection states (connected, disconnected, and unmanaged), and the associated network connections if any (Wired connection 1).

Use case 2: Print the available Wi-Fi access points

Code:

nmcli device wifi

Motivation: This use case is useful when you need to view the available Wi-Fi access points in your vicinity. It can help you identify different Wi-Fi networks, their signal strengths, and other relevant information.

Explanation: The wifi argument is provided to the nmcli device command to specify that we want to get information about available Wi-Fi access points.

Example output:

IN-USE  SSID             MODE   CHAN  RATE        SIGNAL  BARS  SECURITY
        MyWiFiNetwork    Infra  1     135 Mbps    45      ▂▄▆_  WPA2
        AnotherNetwork   Infra  6     300 Mbps    75      ▂▄▆█  WPA1 WPA2
        GuestNetwork     Infra  11    54 Mbps     25      ▂___  Open

In the example output, you can see the SSID (network name), mode, channel, transmission rate, signal strength, signal bars, and security type.

Use case 3: Connect to a Wi-Fi network with the specified SSID (you will be prompted for a password)

Code:

nmcli --ask device wifi connect ssid

Motivation: This use case is helpful when you want to connect to a specific Wi-Fi network. By providing the SSID of the network, you can easily initiate a connection and input the password when prompted.

Explanation: The --ask option is added to the command to prompt the user for the Wi-Fi password. The connect argument is used to specify that we want to connect to a Wi-Fi network with the given SSID.

Example output:

Password: ******
Device 'wlan0' successfully activated with 'MyWiFiNetwork'.

In the example output, the user is prompted to enter the Wi-Fi password. Once entered correctly, the connection is established, and the name of the activated device along with the connected network’s SSID is displayed.

Use case 4: Print the password and QR code for the current Wi-Fi network

Code:

nmcli device wifi show-password

Motivation: This use case is useful when you want to view the password for the currently connected Wi-Fi network. It can be handy for sharing the password with others or for reference purposes.

Explanation: The show-password argument is added to the nmcli device wifi command to display the password for the current Wi-Fi network.

Example output:

MyWiFiNetwork:
  password: MyPassword123
  QR-Code: █████████████████████

In the example output, you can see the SSID of the current Wi-Fi network (MyWiFiNetwork), its associated password (MyPassword123), and a QR code representation of the network.

Conclusion:

The nmcli device command provides a versatile set of options to manage network interfaces and handle Wi-Fi connections using NetworkManager. By utilizing these use cases, you can easily retrieve information, connect to Wi-Fi networks, and troubleshoot network-related issues.