The cpio command is a powerful utility used in Unix-like operating systems for creating and extracting archive files. It's particularly useful for handling file archives, often used in conjunction with other commands like find for selecting files and tar for creating tape archives, though cpio itself can create various archive formats.

Cpio Archive Creation

To create a cpio archive, you typically pipe the output of another command (like ls or find) into cpio with the --create (or -o) option. This tells cpio to read a list of filenames from standard input and write them into an archive.

# Create a cpio archive from the current directory's files:
ls | cpio --create --file=archive.cpio

# Create a cpio archive using find for more control:
find . -print | cpio --create --file=archive.cpio

Cpio Archive Extraction

Extracting a cpio archive is done using the --extract (or -i) option. You pipe the archive content into cpio or specify the archive file. The --make-directories (or -d) option is crucial for recreating the directory structure from the archive.

# Extract a cpio archive to the current directory:
cpio --extract --make-directories < archive.cpio

# Extract a cpio archive from standard input:
cat archive.cpio | cpio --extract --make-directories

Cpio Archive Listing

You can also list the contents of a cpio archive without extracting them using the --list (or -t) option. This is useful for inspecting the archive's contents before performing an extraction.

# List the contents of a cpio archive:
cpio --list < archive.cpio

Key Cpio Options

• --create (-o): Create an archive.
• --extract (-i): Extract files from an archive.
• --list (-t): List the contents of an archive.
• --file=FILE (-F FILE): Use FILE as the archive file.
• --make-directories (-d): Create leading directories as needed.
• --verbose (-v): Verbose output.

For more detailed information and advanced usage, refer to the official cpio man page or documentation from sources like Linux man-pages.