cpio man page

cpio — copy files to and from archives


echo "{{file1}} {{file2}} {{file3}}" | cpio -o > {{archive.cpio}}

find {{path/to/directory}} | cpio -ov > {{archive.cpio}}

cpio -idv < {{archive.cpio}}


The cpio utility is considered LEGACY based on POSIX specification. Users are encouraged to use other archiving tools for archive creation.

If you decided to use cpio, you should almost always force cpio to use the ustar format in copy-out mode by the -H option (cpio -o -H ustar). This is because the ustar format is well defined in POSIX specification and thus readable by wide range of other archiving tools (including tar e.g.).

By default, GNU cpio uses (for historical reasons) the very old binary format ('bin') which has significant problems nowadays, e.g. with storing big inode numbers (see the Red Hat bug #952313).

Note also that these days the modern 'pax' archive format should be considered as the default -- but this format is not implemented in GNU cpio. You should, again, consider using other archivers (e.g. 'tar --format=pax').


Copy-out mode

In copy-out mode, cpio copies files into an archive. It reads a list of filenames, one per line, on the standard input, and writes the archive onto the standard output. A typical way to generate the list of filenames is with the find command; you should give find the -depth option to minimize problems with permissions on directories that are unreadable. see “Options”.

cpio {-o|--create} [-0acvABLV] [-C bytes] [-H format] [-D DIR] [-M message] [-O [[user@]host:]archive] [-F [[user@]host:]archive] [--file=[[user@]host:]archive] [--format=format] [--warning=FLAG] [--message=message][--null] [--reset-access-time] [--verbose] [--dot] [--append] [--block-size=blocks] [--dereference] [--io-size=bytes] [--rsh-command=command] [--license] [--usage] [--help] [--version] < name-list [> archive]

Copy-in mode

In copy-in mode, cpio copies files out of an archive or lists the archive contents. It reads the archive from the standard input. 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. Unlike in the shell, an initial `.' in a filename does match a wildcard at the start of a pattern, and a `/' in a filename can match wildcards. If no patterns are given, all files are extracted. see “Options”.

cpio {-i|--extract} [-bcdfmnrtsuvBSV] [-C bytes] [-E file] [-H format] [-D DIR] [-M message] [-R [user][:.][group]] [-I [[user@]host:]archive] [-F [[user@]host:]archive] [--file=[[user@]host:]archive] [--make-directories] [--nonmatching] [--preserve-modification-time] [--numeric-uid-gid] [--rename] [-t|--list] [--swap-bytes] [--swap] [--dot] [--warning=FLAG] [--unconditional] [--verbose] [--block-size=blocks] [--swap-halfwords] [--io-size=bytes] [--pattern-file=file] [--format=format] [--owner=[user][:.][group]] [--no-preserve-owner] [--message=message] [--force-local] [--no-absolute-filenames] [--absolute-filenames] [--sparse] [--only-verify-crc] [--to-stdout] [--quiet] [--ignore-devno] [--renumber-inodes] [--device-independent] [--reproducible] [--rsh-command=command] [--license] [--usage] [--help] [--version] [pattern...] [< archive]

Copy-pass mode

In copy-pass mode, 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. see “Options”.

cpio {-p|--pass-through} [-0adlmuvLV] [-R [user][:.][group]] [-D DIR] [--null] [--reset-access-time] [--make-directories] [--link] [--quiet] [--preserve-modification-time] [--unconditional] [--verbose] [--dot] [--warning=FLAG] [--dereference] [--owner=[user][:.][group]] [--no-preserve-owner] [--sparse] [--license] [--usage] [--help] [--version] destination-directory < name-list


GNU cpio is a tool for creating and extracting archives, or copying files from one place to another. It handles a number of cpio formats as well as reading and writing tar files.

Following archive formats are supported: binary, old ASCII, new ASCII, crc, HPUX binary, HPUX old ASCII, old tar, and POSIX.1 tar. The tar format is provided for compatibility with the tar program. By default, cpio creates binary format archives, for compatibility with older cpio programs. When extracting from archives, cpio automatically recognizes which kind of archive it is reading and can read archives created on machines with a different byte-order.

Main operation mode

-i, --extract
Extract files from an archive (run in copy-in mode)
-o, --create
Create the archive (run in copy-out mode)
-p, --pass-through
Run in copy-pass mode
-t, --list
Print a table of contents of the input

Operation modifiers valid in any mode

Set the I/O block size to BLOCK-SIZE * 512 bytes
Set the I/O block size to 5120 bytes. Initially the block size is 512 bytes.
Identical to "-H newc", use the new (SVR4) portable format. If you wish the old portable (ASCII) archive format, use "-H odc" instead.
-C, --io-size=NUMBER
Set the I/O block size to the given NUMBER of bytes
-D, --directory=DIR
Change to directory DIR
With -F, -I, or -O, take the archive file name to be a local file even if it contains a colon, which would ordinarily indicate a remote host name.
-H, --format=FORMAT
Use given archive FORMAT. The valid formats are listed below; the same names are also recognized in all-caps. The default in copy-in mode is to automatically detect the archive format, and in copy-out mode is `bin'.
The obsolete binary format.
The old (POSIX.1) portable format.
The new (SVR4) portable format, which supports file systems having more than 65536 i-nodes.
The new (SVR4) portable format with a checksum (Sum32) added.
The old tar format.
The POSIX.1 tar format. Also recognizes GNU tar archives, which are similar but not identical.
The obsolete binary format used by HPUX's cpio (which stores device files differently).
The portable format used by HPUX's cpio (which stores device files differently).
Do not print the number of blocks copied
-R, --owner=[USER][:.][GROUP]
Set the ownership of all files created to the specified USER and/or GROUP. Either the user, the group, or both, must be present. If the group is omitted but the “:” or “.” separator is given, use the given user's login group. Only the super-user can change files' ownership in copy-in mode.
-v, --verbose
List the files processed, or with `-t', give an `ls -l' style table of contents listing. In a verbose table of contents of a ustar archive, user and group names in the archive that do not exist on the local system are replaced by the names that correspond locally to the numeric UID and GID stored in the archive.
-V, --dot
Print a "." for each file processed
-W, --warning=FLAG
Control warning display. Currently FLAG is one of 'none', 'truncate', 'all'. Multiple options accumulate.

Operation modifiers valid in copy-in and copy-out modes

-F, --file=[[USER@]HOST:]FILE-NAME
Use this FILE-NAME instead of standard input or output. Optional USER and HOST specify the user and host names in case of a remote archive
-M, --message=STRING
Print STRING when the end of a volume of the backup media (such as a tape or a floppy disk) is reached, to prompt the user to insert a new volume. If STRING contains the string “%d”, it is replaced by the current volume number (starting at 1).
Use COMMAND instead of rsh (typically /usr/bin/ssh)

Operation modifiers valid only in copy-in mode

-b, --swap
Swap both halfwords of words and bytes of halfwords in the data. Equivalent to -sS Use this option to convert 32-bit integers between big-endian and little-endian machines.
-f, --nonmatching
Only copy files that do not match any of the given patterns
Archive filename to use instead of standard input. Optional USER and HOST specify the user and host names in case of a remote archive
-n, --numeric-uid-gid
In the verbose table of contents listing, show numeric UID and GID
-r, --rename
Interactively rename files
-s, --swap-bytes
Swap the bytes of each halfword in the files
-S, --swap-halfwords
Swap the halfwords of each word (4 bytes) in the files
Extract files to standard output
-E, --pattern-file=FILE
Read additional patterns specifying filenames to extract or list from FILE
When reading a CRC format archive, only verify the checksum of each file in the archive, don't actually extract the files

Operation modifiers valid only in copy-out mode

-A, --append
Append to an existing archive. The archive must be a disk file specified with the -O or -F (-file) option.
--device-independent, --reproducible
Create device-independent (reproducible) archives
Don't store device numbers
Archive filename to use instead of standard output. Optional USER and HOST specify the user and host names in case of a remote archive
Renumber inodes

Operation modifiers valid only in copy-pass mode

-l, --link
Link files instead of copying them, when possible

Operation modifiers valid in copy-in and copy-out modes

Do not strip file system prefix components from the file names
Create all files relative to the current directory

Operation modifiers valid in copy-out and copy-pass modes

-0, --null
Filenames in the list are delimited by null characters instead of newlines, so that files whose names contain newlines can be archived. GNU find is one way to produce a list of null-terminated filenames.
-a, --reset-access-time
Reset the access times of files after reading them, so that it does not look like they have just been read.
-L, --dereference
Dereference symbolic links (copy the files that they point to instead of copying the links).

Operation modifiers valid in copy-in and copy-pass modes

-d, --make-directories
Create leading directories where needed
-m, --preserve-modification-time
Retain previous file modification times when creating files
Do not change the ownership of the files; leave them owned by the user extracting them. This is the default for non-root users, so that users on System V don't inadvertently give away files. This option can be used in copy-in mode and copy-pass mode
Write files with large blocks of zeros as sparse files
-u, --unconditional
Replace all files unconditionally
-?, --help
give this help list
give a short usage message
print program version

Mandatory or optional arguments to long options are also mandatory or optional for any corresponding short options.


When creating an archive, cpio takes the list of files to be processed from the standard input, and then sends the archive to the standard output, or to the device defined by the `-F' option. Usually find or ls is used to provide this list to the standard input. In the following example you can see the possibilities for archiving the contents of a single directory.

% ls | cpio -ov > directory.cpio

The `-o' option creates the archive, and the `-v' option prints the names of the files archived as they are added. Notice that the options can be put together after a single `-' or can be placed separately on the command line. The `>' redirects the cpio output to the file `directory.cpio'.

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

This will take all the files in the current directory, the directories below and place them in the archive tree.cpio. Again the `-o' creates an archive, and the `-v' option shows you the name of the files as they are archived. see “Copy-out mode”. Using the `.' in the find statement will give you more flexibility when doing restores, as it will save file names with a relative path vice a hard wired, absolute path. The `-depth' option forces `find' to print of the entries in a directory before printing the directory itself. This limits the effects of restrictive directory permissions by printing the directory entries in a directory before the directory name itself.

Extracting an archive requires a bit more thought because cpio will not create directories by default. Another characteristic, is it will not overwrite existing files unless you tell it to.

% cpio -iv < directory.cpio

This will retrieve the files archived in the file directory.cpio and place them in the present directory. The `-i' option extracts the archive and the `-v' shows the file names as they are extracted. If you are dealing with an archived directory tree, you need to use the `-d' option to create directories as necessary, something like:

% cpio -idv < tree.cpio

This will take the contents of the archive tree.cpio and extract it to the current directory. If you try to extract the files on top of files of the same name that already exist (and have the same or later modification time) cpio will not extract the file unless told to do so by the -u option. see “Copy-in mode”.

In copy-pass mode, 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. see “Copy-pass mode”.

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

The example shows copying the files of the present directory, and sub-directories to a new directory called new-dir. Some new options are the `-print0' available with GNU find, combined with the `--null' option of cpio. These two options act together to send file names between find and cpio, even if special characters are embedded in the file names. Another is `-p', which tells cpio to pass the files it finds to the directory `new-dir'.


Written by Phil Nelson, David MacKenzie, John Oleynick, and Sergey Poznyakoff.

Reporting Bugs

Report bugs to <bug-cpio@gnu.org>. Report bugs in this manual page via https://bugzilla.redhat.com.

See Also

The online copy of the documentation is available at the following address:


Referenced By

archivemount(1), attr(1), bsdtar(1), bup-split(1), cpdup(1), cpio(5), libarchive-formats(5), opax(1), star(1).