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プロジェクトリンク

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コマンドとエイリアス

• file

プロジェクトの歴史

Ian Darwin's official page distinguishes the historical Bell Labs Unix file command from his free reimplementation. It notes that the original command shipped with Bell Labs Unix, including a Research 4th Edition man page from 1973, but was not generally available in source form before Darwin's reimplementation.

Darwin's implementation and magic file began in 1987; the page shows an RCS initial revision dated August 23, 1987. The README describes Release 5.x as Ian Darwin's implementation of the Unix file command and says it knows the magic numbers of several thousand file types.

Maintenance later broadened. The README credits Guy Harris as the prime contributor to Release 3.8, Christos Zoulas as the prime contributor to Release 3.0, and Mans Rullgard as the prime contributor to 4.0, where the code was refactored into libmagic and the file command was rewritten on top of that library.

採用の歴史

The official README states that this version is the standard file command for Linux, BSD, and other systems. Darwin's page adds that it ships with most free operating systems, has been ported to systems including DOS, Microsoft Windows, and OS/2, and that OpenBSD uses the project's configuration files even though it maintains its own code.

The supplied package metadata reflects that platform reach, listing packages across Homebrew, Alpine, Debian, Ubuntu, Fedora, MacPorts, Nix, Arch, Scoop, Chocolatey, winget, and openSUSE.

使われ方

The command-line use is simple: pass paths to file and receive textual guesses about their data type. The important behavior is that it examines file contents, including filesystem data, magic rules, and hardwired text/encoding checks, rather than relying on filename extensions.

The libmagic split made the same detection engine reusable by other programs without spawning the file command. The README and homepage call out libmagic as a library interface for third-party file-type detection.

パッケージ好きにとっての重要性

file is one of the core Unix plumbing commands package maintainers take for granted until it is missing, stale, or misdetecting a format. It underpins configure scripts, build systems, MIME/type detection, archive inspection, and debugging sessions.

Its magic database is also culturally important: maintaining file means maintaining a compact, portable folk taxonomy of binary formats, text encodings, archives, executable formats, and application data.

タイムライン

• 1973: A Research 4th Edition Unix file man page documents the earlier Bell Labs command.
• 1987: Ian Darwin's RCS history records the initial revision of his free implementation.
• Release 3.0: Christos Zoulas contributes major code changes.
• Release 3.8: Guy Harris contributes byte-order independence and other large changes.
• Release 4.0: The code is refactored into libmagic plus a command-line frontend.
• Release 5.x: The README identifies it as the standard file command for Linux, BSD, and other systems.

Related projects

• file is related to libmagic consumers, MIME detection systems, Unix magic(5) databases, package build tooling, and operating-system file managers that need content-based type detection.

ソース

• https://darwinsys.com/file
• https://github.com/file/file#readme