Filelocal

Filelocal is a computing concept that denotes data, settings, or resources that are scoped to a single file rather than to a broader project, workspace, or system. The term describes a mechanism for per-file customization, allowing specific behavior or metadata to apply only to that file. File-local information can be embedded within the file itself, stored in a sidecar file, or held as file-level metadata.

In Emacs, file-local variables provide a concrete example of filelocal semantics. A file can declare a set of variables that should apply when the file is opened, typically via a Local Variables section near the end of the file. Emacs applies these values to the associated buffer, with safeguards that may prompt the user when potential security risks are detected.

Other tools and environments implement similar per-file overrides. Some editors let users tailor lint rules, formatting, or language settings per file. Build systems may use per-file attributes to influence compilation flags or dependency handling. In these contexts, filelocal settings can be stored as in-file declarations or as separate metadata files, enabling fine-grained control without altering global configurations.

Security and manageability considerations accompany filelocal use. Because per-file settings can override broader defaults, editors and toolchains often provide warnings, validation, or explicit consent requirements before applying these settings, to prevent unintended or unsafe changes.

See also: local variables, per-file metadata, per-file configuration, sidecar files.