Nix Glossary: Store Outputs, Path Validity, User Environments, and Archives

A [store object] produced by a [store derivation]. See [the `outputs` argument to the `derivation` function](@docroot@/language/derivations.md#attr-outputs) for details. - [output path]{#gloss-output-path} The [store path] to the [output] of a [store derivation]. - [output closure]{#gloss-output-closure}\ The [closure] of an [output path]. It only contains what is [reachable] from the output. - [deriving path]{#gloss-deriving-path} Deriving paths are a way to refer to [store objects][store object] that might not yet be [realised][realise]. See [Deriving Path](./store/derivation/index.md#deriving-path) for details. Not to be confused with [derivation path]. - [deriver]{#gloss-deriver} The [store derivation] that produced an [output path]. The deriver for an output path can be queried with the `--deriver` option to [`nix-store --query`](@docroot@/command-ref/nix-store/query.md). - [validity]{#gloss-validity} A store path is valid if all [store object]s in its [closure] can be read from the [store]. For a [local store], this means: - The store path leads to an existing [store object] in that [store]. - The store path is listed in the [Nix database] as being valid. - All paths in the store path's [closure] are valid. - [user environment]{#gloss-user-env} An automatically generated store object that consists of a set of symlinks to “active” applications, i.e., other store paths. These are generated automatically by [`nix-env`](./command-ref/nix-env.md). See *profiles*. - [profile]{#gloss-profile} A symlink to the current *user environment* of a user, e.g., `/nix/var/nix/profiles/default`. - [installable]{#gloss-installable} Something that can be realised in the Nix store. See [installables](./command-ref/new-cli/nix.md#installables) for [`nix` commands](./command-ref/new-cli/nix.md) (experimental) for details. - [Nix Archive (NAR)]{#gloss-nar} A *N*ix *AR*chive. This is a serialisation of a path in the Nix store. It can contain regular files, directories and symbolic links. NARs are generated and unpacked using `nix-store --dump` and `nix-store --restore`. See [Nix Archive](store/file-system-object/content-address.html#serial-nix-archive) for details. - [`∅`]{#gloss-empty-set} The empty set symbol. In the context of profile history, this denotes a package is not present in a particular version of the profile. - [`ε`]{#gloss-epsilon}

This glossary defines terms related to Nix store objects, their states, user configurations, and data serialization. It covers 'output' (a store object from a derivation), 'output path' (its location), and 'output closure' (all reachable components from an output). 'Deriving path' refers to potentially unrealized store objects, while 'deriver' is the derivation that produced a specific output. 'Validity' is defined for a store path, ensuring all its components are readable and correctly listed in the Nix database. User-centric terms include 'user environment' (symlinks to active applications) and 'profile' (a symlink to the current user environment). 'Installable' denotes anything that can be realized in the Nix store. 'Nix Archive (NAR)' is explained as a serialization format for store paths. Lastly, '∅' represents an empty set, specifically a package's absence in a profile version.