cbrst/nixValidating changes
Build and check changes without activating them.
The installed system and home directory always reflect the last activated generation, not the working tree. A change has to be evaluated or built before you can judge it; testing it against the installed programs only tests the old generation.
Run these from /etc/nix-config. None of them activate anything.
# Evaluate the flake
nix flake show --no-write-lock-file .
nix flake check --no-build --no-write-lock-file .
# Build the system configurations
nix build --no-link '.#nixosConfigurations.asgard.config.system.build.toplevel'
nix build --no-link '.#nixosConfigurations.example-nixos.config.system.build.toplevel'
# Build Asgard's embedded Home Manager configuration
nix build --no-link \
'.#nixosConfigurations.asgard.config.home-manager.users.cbrst.home.activationPackage'
# Build or evaluate the standalone Home Manager outputs
nix build --no-link '.#homeConfigurations."example-user@generic-linux".activationPackage'
nix eval '.#homeConfigurations."example-user@macbook".activationPackage.drvPath'
nix eval '.#homeConfigurations."cbrst@niflheim".activationPackage.drvPath'--no-link avoids creating a result symlink in the repository. The macOS
outputs can only be evaluated on Linux, not built.
Nix evaluates the flake from the Git snapshot of the repository. A newly
created file that Git does not know about yet is invisible to the evaluation.
In this colocated jj repository, running any jj command snapshots new files
into the working-copy commit.
Activating
Activation is a separate, explicit step:
# Asgard: system and Home Manager together
sudo nixos-rebuild switch --flake /etc/nix-config#asgard
# Niflheim or another standalone Home Manager host
nix run github:nix-community/home-manager -- switch --flake '.#cbrst@niflheim'On NixOS, every activation prints a package-version diff between the running
system and the new one, produced by nvd (see Base system).
Editor configurations
Neovim and Emacs have their own fast validation paths that load the configuration straight from the checkout. See Neovim and Emacs.
Updating inputs
nix flake update advances every pinned input in flake.lock. Only run it
deliberately; it changes the versions of every package and module the next
build uses.
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