Nix Store
2 min read
The Nix store is the central database of Nix. It is usually located at /nix/store and contains every package, configuration, and build artifact that Nix has produced.
Each entry in the Nix store has a content-addressed path of the form:
/nix/store/<hash>-<name>
• Hash: a cryptographic hash that uniquely identifies the build output, based on all its inputs.
• Name: a human-readable name (often package-version).
This design makes the store immutable, reproducible, and conflict-free — multiple versions of the same software can coexist without interference.
Usage
The nix-store command lets you directly inspect and manipulate the Nix store. While most users interact with it indirectly (through nix, nixos-rebuild, or nix-env), it’s useful for low-level operations.
Querying the Store
• Show all store paths currently present:
bash
nix-store --query --requisites /run/current-system
This prints the closure (all dependencies) of your current system configuration.
• Print all store paths known to the system:
bash
nix-store --query --all
• Show what a store path depends on:
bash
nix-store --query --references /nix/store/<hash>-<name>
• Show what depends on a store path (reverse dependencies):
bash
nix-store --query --referrers /nix/store/<hash>-<name>
• Inspect its closure (dependencies):
bash
nix-store --query --requisites /nix/store/<hash>-<name>
Garbage Collection
Because the store is immutable, old and unused paths accumulate over time. Nix provides garbage collection (GC) to safely remove unreferenced paths.
• Run garbage collection:
bash
nix-collect-garbage
Removes unused store paths not reachable from any user or system profile.
• Aggressive cleanup:
bash
nix-collect-garbage -d
Deletes all old generations of profiles, freeing maximum space.
• List what would be collected without deleting:
bash
nix-store --gc --print-dead
• List what is still alive (referenced):
bash
nix-store --gc --print-live