Chapter 20. Running dhclient exit hooks using NetworkManager a dispatcher script

The NetworkManager-dispatcher service executes user-provided scripts in alphabetical order when network events happen. These scripts are typically shell scripts, but can be any executable script or application. You can use dispatcher scripts, for example, to adjust network-related settings that you cannot manage with NetworkManager.

You can store dispatcher scripts in the following directories:

For security reasons, the NetworkManager-dispatcher service executes scripts only if the following conditions met:

The NetworkManager-dispatcher service runs each script with two arguments:

The Dispatcher scripts section in the NetworkManager(8) man page provides an overview of actions and environment variables you can use in scripts.

The NetworkManager-dispatcher service runs one script at a time, but asynchronously from the main NetworkManager process. Note that, if a script is queued, the service will always run it, even if a later event makes it obsolete. However, the NetworkManager-dispatcher service runs scripts that are symbolic links referring to files in /etc/NetworkManager/dispatcher.d/no-wait.d/ immediately, without waiting for the termination of previous scripts, and in parallel.

When a DHCP server assigns or updates an IPv4 address, NetworkManager can run a dispatcher script stored in the /etc/dhcp/dhclient-exit-hooks.d/ directory. This dispatcher script can then, for example, run dhclient exit hooks.