cpio archive for UNIX

cpio is a binary file archiver & a file format basically for the UNIX based systems that ends with .cpio file extensions. Available under the GNU license, cpio software utility was meant to be a tape archiver that was originally part of PWB/UNIX and that was also part of UNIX System III & UNIX System V and is a stream of files & directories in a single archive. Though its later versions, such as tar, are more popular & considered to be a better solutions that cpio itself but it's usage in the RPM Package Manager, the Linux Kernel 2.6 series' initramfs, Oracle's distribution of its software in the cpio format and Apple's 'pax' installer archive continues to make cpio an important archive format.

The header of a cpio archive contains information such as the file names, time stamp, owners & permissions and was designed to store backups onto a tape device in a contiguous manner. Like the Tar format, CPIO archives are often compressed using Gzip and distributed as .cpgz or .cpio.gz files and supports the binary, old & new ASCII, crc, HPUX binary, HPUX old ASCII, old tar & POSIX.1 tar archive formats.

The cpio utility was standardized in POSIX.1-1988 & was dropped from later revisions, starting with POSIX.1-2001 due to its 8 GB filesize limit. The POSIX standardized pax utility can be used to read and write cpio archives instead. The latest release of cpio is version 2.10 that was released on 20-June-2009 after minor bugfixes.