system.preSwitchChecks

A set of shell script fragments that are executed before the switch to a new NixOS system configuration. A failure in any of these fragments will cause the switch to fail and exit early. The scripts receive the new configuration path and the action verb passed to switch-to-configuration, as the first and second positional arguments (meaning that you can access them using $1 and $2, respectively).

Type

attribute set of string

Default

{ }

Example

{ failsEveryTime =
  ''
    false
  '';
}

Declared

<nixpkgs/nixos/modules/system/activation/pre-switch-check.nix>