cpio

Additional Notes

cpio copies files to and from cpio archive streams. It is often seen in initramfs images, RPM internals, and older Unix archive workflows.

Unlike tar, cpio often reads a list of filenames from standard input.

Syntax

cpio -o [options] > archive.cpio
cpio -i [options] < archive.cpio
cpio -p [options] directory

Parameters

• -o: Copy-out mode, create an archive.
• -i: Copy-in mode, extract from an archive.
• -p: Pass-through mode, copy files to another directory.
• archive: Archive stream or file.
• directory: Destination for pass-through copy.

Common Options

• -v: Verbose output.
• -d: Create directories as needed.
• -m: Preserve modification times.
• -u: Replace existing files unconditionally.
• -H FORMAT: Select archive format, such as newc.
• --no-absolute-filenames: Avoid extracting absolute paths as absolute.

Examples

find . -print | cpio -ov > archive.cpio

Create a cpio archive from files found under the current directory.

cpio -idv < archive.cpio

Extract an archive, creating directories.

find . -print | cpio -pdm /tmp/copy

Copy a tree using pass-through mode.

Practical Notes

• Be careful extracting archives that contain absolute paths.
• Initramfs archives often use newc format.
• For normal backups, tar is usually easier.