File: cpio.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
cpio
****
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. This is the first edition of the
GNU cpio documentation and is consistant with GNU cpio 2.5.
* Menu:
* Introduction::
* Tutorial:: Getting started.
* Invoking `cpio':: How to invoke `cpio'.
* Media:: Using tapes and other archive media.
* Concept Index:: Concept index.
--- The Detailed Node Listing ---
Invoking cpio
* Copy-out mode::
* Copy-in mode::
* Copy-pass mode::
* Options::
File: cpio.info, Node: Introduction, Next: Tutorial, Prev: Top, Up: Top
1 Introduction
**************
GNU cpio copies files into or out of a cpio or tar archive, The archive
can be another file on the disk, a magnetic tape, or a pipe.
GNU cpio supports the following archive formats: binary, old ASCII,
new ASCII, crc, HPUX binary, HPUX old ASCII, old tar, and POSIX.1 tar.
The tar format is provided for compatability 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.
File: cpio.info, Node: Tutorial, Next: Invoking `cpio', Prev: Introduction, Up: Top
2 Tutorial
**********
GNU cpio performs three primary functions. Copying files to an
archive, Extracting files from an archive, and passing files to another
directory tree. An archive can be a file on disk, one or more floppy
disks, or one or more tapes.
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. *Note
Copy-out mode::. 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. *Note 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. *Note 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. *Note 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'.
File: cpio.info, Node: Invoking `cpio', Next: Media, Prev: Tutorial, Up: Top
3 Invoking cpio
***************
* Menu:
* Copy-out mode::
* Copy-in mode::
* Copy-pass mode::
* Options::
File: cpio.info, Node: Copy-out mode, Next: Copy-in mode, Prev: Invoking `cpio', Up: Invoking `cpio'
3.1 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. *Note Options::.
cpio {-o|--create} [-0acvABLV] [-C bytes] [-H format]
[-M message] [-O [[user@]host:]archive] [-F [[user@]host:]archive]
[--file=[[user@]host:]archive] [--format=format]
[--message=message][--null] [--reset-access-time] [--verbose]
[--dot] [--append] [--block-size=blocks] [--dereference]
[--io-size=bytes] [--rsh-command=command] [--help] [--version]
< name-list [> archive]
File: cpio.info, Node: Copy-in mode, Next: Copy-pass mode, Prev: Copy-out mode, Up: Invoking `cpio'
3.2 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. *Note Options::.
cpio {-i|--extract} [-bcdfmnrtsuvBSV] [-C bytes] [-E file]
[-H format] [-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] [--list] [--swap-bytes] [--swap]
[--dot] [--unconditional] [--verbose] [--block-size=blocks]
[--swap-halfwords] [--io-size=bytes] [--pattern-file=file]
[--format=format] [--owner=[user][:.][group]]
[--no-preserve-owner] [--message=message] [--help] [--version]
[-no-absolute-filenames] [--sparse] [-only-verify-crc] [-quiet]
[--rsh-command=command] [pattern...] [< archive]
File: cpio.info, Node: Copy-pass mode, Next: Options, Prev: Copy-in mode, Up: Invoking `cpio'
3.3 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. *Note Options::.
cpio {-p|--pass-through} [-0adlmuvLV] [-R [user][:.][group]]
[--null] [--reset-access-time] [--make-directories] [--link]
[--preserve-modification-time] [--unconditional] [--verbose]
[--dot] [--dereference] [--owner=[user][:.][group]] [--sparse]
[--no-preserve-owner] [--help] [--version] destination-directory
< name-list
File: cpio.info, Node: Options, Prev: Copy-pass mode, Up: Invoking `cpio'
3.4 Options
===========
`-0, --null'
Read a list of filenames terminated by a null character, instead
of a newline, so that files whose names contain newlines can be
archived. GNU find is one way to produce a list of
null-terminated filenames. This option may be used in copy-out
and copy-pass modes.
`-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.
`-A, --append'
Append to an existing archive. Only works in copy-out mode. The
archive must be a disk file specified with the -O or -F (-file)
option.
`-b, --swap'
Swap both halfwords of words and bytes of halfwords in the data.
Equivalent to -sS. This option may be used in copy-in mode. Use
this option to convert 32-bit integers between big-endian and
little-endian machines.
`-B'
Set the I/O block size to 5120 bytes. Initially the block size is
512 bytes.
`--block-size=BLOCK-SIZE'
Set the I/O block size to BLOCK-SIZE * 512 bytes.
`-c'
Use the old portable (ASCII) archive format.
`-C IO-SIZE, --io-size=IO-SIZE'
Set the I/O block size to IO-SIZE bytes.
`-d, --make-directories'
Create leading directories where needed.
`-E FILE, --pattern-file=FILE'
Read additional patterns specifying filenames to extract or list
from FILE. The lines of FILE are treated as if they had been
non-option arguments to cpio. This option is used in copy-in mode,
`-f, --nonmatching'
Only copy files that do not match any of the given patterns.
`-F, --file=archive'
Archive filename to use instead of standard input or output. To
use a tape drive on another machine as the archive, use a filename
that starts with `HOSTNAME:'. The hostname can be preceded by a
username and an `@' to access the remote tape drive as that user,
if you have permission to do so (typically an entry in that user's
`~/.rhosts' file).
`--force-local'
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=FORMAT'
Use archive format 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'.
`bin'
The obsolete binary format.
`odc'
The old (POSIX.1) portable format.
`newc'
The new (SVR4) portable format, which supports file systems
having more than 65536 i-nodes.
`crc'
The new (SVR4) portable format with a checksum added.
`tar'
The old tar format.
`ustar'
The POSIX.1 tar format. Also recognizes GNU tar archives,
which are similar but not identical.
`hpbin'
The obsolete binary format used by HPUX's cpio (which stores
device files differently).
`hpodc'
The portable format used by HPUX's cpio (which stores device
files differently).
`-i, --extract'
Run in copy-in mode. *Note Copy-in mode::.
`-I archive'
Archive filename to use instead of standard input. To use a tape
drive on another machine as the archive, use a filename that
starts with `HOSTNAME:'. The hostname can be preceded by a
username and an `@' to access the remote tape drive as that user,
if you have permission to do so (typically an entry in that user's
`~/.rhosts' file).
`-k'
Ignored; for compatibility with other versions of cpio.
`-l, --link'
Link files instead of copying them, when possible.
`-L, --dereference'
Copy the file that a symbolic link points to, rather than the
symbolic link itself.
`-m, --preserve-modification-time'
Retain previous file modification times when creating files.
`-M MESSAGE, --message=MESSAGE'
Print MESSAGE 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 MESSAGE contains the string "%d", it is
replaced by the current volume number (starting at 1).
`-n, --numeric-uid-gid'
Show numeric UID and GID instead of translating them into names
when using the `--verbose option'.
`--no-absolute-filenames'
Create all files relative to the current directory in copy-in
mode, even if they have an absolute file name in the archive.
`--no-preserve-owner'
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 inadvertantly give away files. This
option can be used in copy-in mode and copy-pass mode
`-o, --create'
Run in copy-out mode. *Note Copy-out mode::.
`-O archive'
Archive filename to use instead of standard output. To use a tape
drive on another machine as the archive, use a filename that
starts with `HOSTNAME:'. The hostname can be preceded by a
username and an `@' to access the remote tape drive as that user,
if you have permission to do so (typically an entry in that user's
`~/.rhosts' file).
`--only-verify-crc'
Verify the CRC's of each file in the archive, when reading a CRC
format archive. Don't actually extract the files.
`-p, --pass-through'
Run in copy-pass mode. *Note Copy-pass mode::.
`--quiet'
Do not print the number of blocks copied.
`-r, --rename'
Interactively rename files.
`-R [user][:.][group], --owner [user][:.][group]'
Set the ownership of all files created to the specified user and/or
group in copy-out and copy-pass modes. 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.
`--rsh-command=COMMAND'
Notifies cpio that is should use COMMAND to communicate with remote
devices.
`-s, --swap-bytes'
Swap the bytes of each halfword (pair of bytes) in the files.This
option can be used in copy-in mode.
`-S, --swap-halfwords'
Swap the halfwords of each word (4 bytes) in the files. This
option may be used in copy-in mode.
`--sparse'
Write files with large blocks of zeros as sparse files. This
option is used in copy-in and copy-pass modes.
`-t, --list'
Print a table of contents of the input.
`-u, --unconditional'
Replace all files, without asking whether to replace existing
newer files with older files.
`-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.
`--version'
Print the cpio program version number and exit.
File: cpio.info, Node: Media, Next: Concept Index, Prev: Invoking `cpio', Up: Top
4 Magnetic Media
****************
Archives are usually written on removable media-tape cartridges, mag
tapes, or floppy disks.
The amount of data a tape or disk holds depends not only on its size,
but also on how it is formatted. A 2400 foot long reel of mag tape
holds 40 megabytes of data when formated at 1600 bits per inch. The
physically smaller EXABYTE tape cartridge holds 2.3 gigabytes.
Magnetic media are re-usable-once the archive on a tape is no longer
needed, the archive can be erased and the tape or disk used over. Media
quality does deteriorate with use, however. Most tapes or disks should
be disgarded when they begin to produce data errors.
Magnetic media are written and erased using magnetic fields, and
should be protected from such fields to avoid damage to stored data.
Sticking a floppy disk to a filing cabinet using a magnet is probably
not a good idea.
File: cpio.info, Node: Concept Index, Prev: Media, Up: Top
Concept Index
*************
[index]
* Menu:
* command line options: Invoking `cpio'. (line 6)
* copying directory structures: Tutorial. (line 6)
* creating a cpio archive: Tutorial. (line 6)
* extracting a cpio archive: Tutorial. (line 6)
* invoking cpio: Invoking `cpio'. (line 6)
* magnetic media: Media. (line 6)
* passing directory structures: Tutorial. (line 6)
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