Reference

CPIO

CPIO ("copy in, copy out") is a Unix archive format that bundles many files into one stream, similar to tar. It is used in software packaging (inside RPM packages) and in Linux initial-RAM-disk (initramfs) images.

Files & formatsGeneral

CPIO

Also known as: CPIO file, .cpio archive, copy in copy out

Unix archive format similar to tar
Used inside RPM packages and Linux initramfs
Extracted with cpio, bsdtar, or 7-Zip

A tar-like archiver

Like tar, CPIO packs many files into a single archive without compressing them, preserving names and permissions. It reads file lists from input, which is where "copy in, copy out" comes from.

Though less common for everyday use than tar, it persists in important places under the hood of Linux systems.

Where CPIO is used

RPM packages and Linux initramfs (the early-boot RAM filesystem) are built on CPIO archives. The `cpio` command and tools like 7-Zip and bsdtar extract them; they are often paired with gzip for compression.

Related terms

Keep reading the reference.

Files & formatsTARTAR (tape archive) bundles many files and folders into one .tar file but does not compress them on its own. It is almost always paired with a compressor, producing combinations like tar.gz (gzip) or tar.xz.General Files & formatsGZIP (.gz)GZIP is a fast, single-file compressor that produces .gz files. It compresses one file at a time, so to pack a whole folder it is combined with TAR into a tar.gz. It is the default compression behind much of the web and Unix tooling.General Files & formatsArchive fileAn archive file bundles many files and folders into one container — for example a ZIP, RAR, or 7z. Most archives also compress their contents to save space, but some (like plain TAR) only bundle without shrinking anything.General