What Is a CPIO File and Where Is It Used?
CPIO is one of the oldest Unix archive formats, predating TAR. The name stands for "copy in, copy out" and refers to the original command line usage pattern. CPIO is used as the payload format inside RPM packages, as the basis for Linux initramfs (initial RAM filesystem) images, and in some macOS system update components. Most users encounter CPIO files when extracting RPM packages or examining Linux boot images. RPM packages wrap CPIO archives as their payload, and extracting those packages on Mac is covered in open RPM files on Mac. CPIO is one of many Unix archive types in the supported archive formats list on UnFox.
Tip
CPIO files are most commonly found inside RPM packages and Linux boot images. You rarely encounter them as standalone files.
How Do You Extract a CPIO File on Mac?
Drag the .cpio file onto UnFox. The app reads the CPIO header format (which may be binary, old ASCII, or new ASCII) and extracts all entries to a folder. UnFox preserves the directory structure stored in the CPIO archive. The Terminal alternative requires the cpio command with specific flags, which UnFox eliminates entirely. You can download UnFox for free from the Mac App Store to start extracting CPIO archives immediately.
How Does CPIO Relate to Other Unix Archive Formats?
CPIO and TAR both bundle files without compression, but they use different header structures and metadata storage approaches. AR is a third Unix archive format primarily used for static libraries (.a files) and Debian packages, and its extraction workflow is covered in open AR files on Mac. MTREE is a related BSD format used for describing filesystem hierarchies with checksums, and parsing those manifests is covered in open MTREE files on Mac. Mac users who encounter a variety of archive formats can follow the same drag and drop workflow for all of them, as explained in the general guide on how to unzip files on Mac.
