Format de fichier

À propos des fichiers AR

AR (Unix AR Archive · Format d'archive)

Lancement 1971 Par Bell Labs (Unix V1)

Unix AR Archive (.ar) est un format de fichier pris en charge par KaijuConverter pour l’archivage, l’échange professionnel et la conversion multiplateforme.

Famille

Archives & Compressed

Extension

.ar

Type MIME

application/x-archive

Utilisable comme

Entrée

L'histoire

COMMENT AR
A VU LE JOUR.

1971

1977

1979

1993

`ar` is the archive utility that shipped with Unix First Edition in 1971, making it older than tar (1979), cpio (1977), and almost every other Unix concept still in daily use. The original purpose was bundling .o object files into static libraries (.a files) — and that’s still what ar does for every C/C++ project compiled on Earth. When you link against `libm.a` or `libpthread.a`, the static archive was produced by ar decades ago.

ar has a second modern role: Debian .deb packages. Ian Murdock’s 1993 .deb format wraps a control tarball and a data tarball inside an ar archive. `ar t package.deb` will list the three internal members — every .deb ever installed went through ar. Outside those two niches (static libraries and .deb payload) ar is rare, but both niches are so load-bearing that ar will outlive most of us.

CURIOSITÉS ET
ANECDOTES.

`ar` predates tar by 8 years — it's one of the oldest Unix commands still in daily use.

Every static library .a file on your system (libm.a, libpthread.a) is an ar archive.

Every Debian .deb package is an ar archive containing three files: debian-binary, control.tar.*, and data.tar.*.

The `ar` magic number is "!<arch>\n" — a literal 8-byte string you can spot in a hex editor.

GNU ar, BSD ar, and Apple's ar use slightly different extended-filename conventions — a long-filename in one flavor may not read in another.

POINTS FORTS ET
LIMITES.

Points forts

Universal Unix static-library format since 1971.
Used as container for .deb packages.
Simple structure — easy to parse.
55+ years of stability.

Limites

Minimal metadata.
Multiple extended-filename variants cause subtle incompatibilities.
Not a general-purpose archive format.
No compression.

Tailles et poids typiques

Small static library (libm.a)

500 KB - 5 MB

Large C++ template library

50-500 MB

.deb package (wrapping two tar.gz)

100 KB - 300 MB

Spécifications techniques

MIME type: application/x-archive
Extensions: .a (static library), .ar (generic)
Magic number: "!<arch>\n" (first 8 bytes)
Used in: Static libraries, .deb package wrappers
Tools: ar, ranlib, nm

CONVERTIR DEPUIS
AR

ar zip ar 7z ar tar ar gz ar bz2 ar xz ar lzma ar zst ar lz4 ar cpio ar apk ar deb ar rpm

CONVERTIR EN
AR

lzma ar zst ar lz4 ar cpio ar apk ar deb ar rpm ar

Cas d'usage courants

Static library archives, Debian package format, Unix development toolchains