cpio

When creating archives during the copy-out operation, initiated with the -o command line flag, cpio reads file and directory path names from its standard input channel and writes the resulting archive byte stream to its standard output. Cpio is therefore typically used with other utilities that generate the list of files to be archived, such as the find program.

The resulting cpio archive is a sequence of files and directories concatenated into a single archive, separated by header sections with file meta information, such as filename, inode number, ownership, permissions, and timestamps. By convention, the file name of an archive is usually given the file extension cpio.

This example uses the find utility to generate a list of path names starting in the current directory to create an archive of the directory tree:

$ find . -depth -print | cpio -o > /path/archive.cpio

During the copy-in operation, initiated by the command line flag i, cpio reads an archive from its standard input and recreates the archived files in the operating system's file system.

$ cpio -i -vd < archive.cpio

Command line flag d tells cpio to construct directories as necessary. Flag v (verbose) lists file names as they are extracted.

Any remaining command line arguments other than the option flags are shell-like globbing-patterns; only files in the archive with matching names are copied from the archive. The following example extracts the file /etc/fstab from the archive:

$ cpio -i -d /etc/fstab < archive.cpio

The files contained in a cpio archive may be listed with this invocation:

$ cpio -t < archive.cpio

List may be useful since a cpio archive may contain absolute rather than relative paths (e.g., /bin/ls vs. bin/ls).

Cpio supports a third type of operation which copies files. It is initiated with the pass-through option flag (p). This mode combines the copy-out and copy-in steps without actually creating any file archive. In this mode, cpio reads path names on standard input like the copy-out operation, but instead of creating an archive, it recreates the directories and files at a different location in the file system, as specified by the path given as a command line argument.

This example copies the directory tree starting at the current directory to another path new-path in the file system, preserving files modification times (flag m), creating directories as needed (d), replacing any existing files unconditionally (u), while producing a progress listing on standard output (v):

$ find . -depth -print | cpio -p -dumv new-path