Open IO File
IO file extension is a compressed file format used in Unix / Linux based operating systems.
IO files are frequently created by the CPIO program, which is a general utility for compressing files and has been a component of virtually all Unix operating systems.
Its name, IO, is derived from the phrase copy "in and out".
IO formats are commonly used by system tools such as the RPM package manager or the initramfs kernel image files.
IO files are much less popular with typical Unix users due to the prevalence of the ubiquitous TAR file format on Linux.