Cpio

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cpio is both the name of a binary utility, and a form of digital archive.

Contents 1 cpio archive 2 POSIX and cpio 3 GNU cpio 3.1 Example use 4 See also 5 External links

[edit] cpio archive

A cpio archive is a stream of files and directories in a single archive, and often ends with a .cpio file extension. The archive has header information that allows for an application such as the GNU cpio tool to extract the files and directories into a file system. The header of a cpio archive also contains information such as the file name, time stamp, owner and permissions.

The cpio archive is similar in function to that of a tar archive, and was designed to store backups onto a tape device in a contiguous manner.

[edit] POSIX and cpio

The cpio utility was standardized in POSIX.1-1988. It was dropped from later revisions, starting with POSIX.1-2001 due to its 8GB filesize limit. The POSIX standardized pax utility can be used to read and write cpio archives instead.

[edit] GNU cpio

The GNU cpio application is a common tool that can be used to put information into a cpio or tar archive. The cpio application is free software, and is available from the GNU web site.

[edit] Example use

If you wanted to archive an entire directory tree, the find command can provide the file list to cpio:

% find . -print -depth | cpio -ov > tree.cpio

Cpio copies files from one directory tree to another, combining the copy-out and copy-in steps without actually using an archive. It reads the list of files to copy from the standard input; the directory into which it will copy them is given as a non-option argument.

% find . -depth -print0 | cpio --null -pvd new-dir

To extract files from a cpio archive, pass the archive to cpio as its standard input.

% cpio -id < cpiofile

The -i flag indicates that cpio is reading in the archive to extract files, and the -d flag tells cpio to construct directories as necessary. You can also use the -v flag to have file names listed as files are extracted.

Any non-option command line arguments are shell globbing patterns; only files in the archive whose names match one or more of those patterns are copied from the archive. The following example extracts etc/fstab from the archive (the format of the archive contents should be verified with cpio -l first to verify how path is stored) :

% cpio -id etc/fstab < cpiofile

[edit] See also

• List of Unix programs
• List of archive formats

[edit] External links

• GNU cpio manual
• GNU cpio web site