cpio
—
copy files to and from archives
cpio |
-i [options]
[pattern ...] [<
archive] |
cpio |
-o [options]
< name-list [>
archive] |
cpio |
-p [options]
dest-dir < name-list |
cpio
copies files between archives and directories. This
implementation can extract from tar, pax, cpio, zip, jar, ar, and ISO 9660
cdrom images and can create tar, pax, cpio, ar, and shar archives.
The first option to cpio
is a mode
indicator from the following list:
-i
- Input. Read an archive from standard input (unless overridden) and extract
the contents to disk or (if the
-t
option is
specified) list the contents to standard output. If one or more file
patterns are specified, only files matching one of the patterns will be
extracted.
-o
- Output. Read a list of filenames from standard input and produce a new
archive on standard output (unless overridden) containing the specified
items.
-p
- Pass-through. Read a list of filenames from standard input and copy the
files to the specified directory.
Unless specifically stated otherwise, options are applicable in all operating
modes.
-0
,
-
-null
- Read filenames separated by NUL characters instead of newlines. This is
necessary if any of the filenames being read might contain newlines.
-A
- (o mode only) Append to the specified archive. (Not yet implemented.)
-a
- (o and p modes) Reset access times on files after they are read.
-B
- (o mode only) Block output to records of 5120 bytes.
-C
size
- (o mode only) Block output to records of size
bytes.
-c
- (o mode only) Use the old POSIX portable character format. Equivalent to
-
-format
odc.
-d
,
-
-make-directories
- (i and p modes) Create directories as necessary.
-E
file
- (i mode only) Read list of file name patterns from
file to list and extract.
-F
file,
-
-file
file
- Read archive from or write archive to file.
-f
pattern
- (i mode only) Ignore files that match pattern.
-H
format,
-
-format
format
- (o mode only) Produce the output archive in the specified format.
Supported formats include:
- cpio
- Synonym for odc.
- newc
- The SVR4 portable cpio format.
- odc
- The old POSIX.1 portable octet-oriented cpio format.
- pax
- The POSIX.1 pax format, an extension of the ustar format.
- ustar
- The POSIX.1 tar format.
The default format is odc. See
libarchive-formats(5)
for more complete information about the formats currently supported by
the underlying
libarchive(3)
library.
-h
,
-
-help
- Print usage information.
-I
file
- Read archive from file.
-i
,
-
-extract
- Input mode. See above for description.
-
-insecure
- (i and p mode only) Disable security checks during extraction or copying.
This allows extraction via symbolic links, absolute paths, and path names
containing ‘..’ in the name.
-J
,
-
-xz
- (o mode only) Compress the file with xz-compatible compression before
writing it. In input mode, this option is ignored; xz compression is
recognized automatically on input.
-j
- Synonym for
-y
.
-L
- (o and p modes) All symbolic links will be followed. Normally, symbolic
links are archived and copied as symbolic links. With this option, the
target of the link will be archived or copied instead.
-l
,
-
-link
- (p mode only) Create links from the target directory to the original
files, instead of copying.
-
-lrzip
- (o mode only) Compress the resulting archive with
lrzip(1). In input mode, this
option is ignored.
-
-lz4
- (o mode only) Compress the archive with lz4-compatible compression before
writing it. In input mode, this option is ignored; lz4 compression is
recognized automatically on input.
-
-zstd
- (o mode only) Compress the archive with zstd-compatible compression before
writing it. In input mode, this option is ignored; zstd compression is
recognized automatically on input.
-
-lzma
- (o mode only) Compress the file with lzma-compatible compression before
writing it. In input mode, this option is ignored; lzma compression is
recognized automatically on input.
-
-lzop
- (o mode only) Compress the resulting archive with
lzop(1). In input mode, this
option is ignored.
-
-passphrase
passphrase
- The passphrase is used to extract or create an
encrypted archive. Currently, zip is only a format that
cpio
can handle encrypted archives. You shouldn't
use this option unless you realize how insecure use of this option
is.
-m
,
-
-preserve-modification-time
- (i and p modes) Set file modification time on created files to match those
in the source.
-n
,
-
-numeric-uid-gid
- (i mode, only with
-t
) Display numeric uid and
gid. By default, cpio
displays the user and group
names when they are provided in the archive, or looks up the user and
group names in the system password database.
-
-no-preserve-owner
- (i mode only) Do not attempt to restore file ownership. This is the
default when run by non-root users.
-O
file
- Write archive to file.
-o
,
-
-create
- Output mode. See above for description.
-p
,
-
-pass-through
- Pass-through mode. See above for description.
-
-preserve-owner
- (i mode only) Restore file ownership. This is the default when run by the
root user.
-
-quiet
- Suppress unnecessary messages.
-R
[user][:][group], -
-owner
[user][:][group]
- Set the owner and/or group on files in the output. If group is specified
with no user (for example,
-R
:wheel) then the group will be set but not the user.
If the user is specified with a trailing colon and no group (for example,
-R
root:) then the group
will be set to the user's default group. If the user is specified with no
trailing colon, then the user will be set but not the group. In
-i
and -p
modes, this
option can only be used by the super-user. (For compatibility, a period
can be used in place of the colon.)
-r
- (All modes.) Rename files interactively. For each file, a prompt is
written to /dev/tty containing the name of the
file and a line is read from /dev/tty. If the line
read is blank, the file is skipped. If the line contains a single period,
the file is processed normally. Otherwise, the line is taken to be the new
name of the file.
-t
,
-
-list
- (i mode only) List the contents of the archive to stdout; do not restore
the contents to disk.
-u
,
-
-unconditional
- (i and p modes) Unconditionally overwrite existing files. Ordinarily, an
older file will not overwrite a newer file on disk.
-V
,
-
-dot
- Print a dot to stderr for each file as it is processed. Superseded by
-v
.
-v
,
-
-verbose
- Print the name of each file to stderr as it is processed. With
-t
, provide a detailed listing of each file.
-
-version
- Print the program version information and exit.
-y
- (o mode only) Compress the archive with bzip2-compatible compression
before writing it. In input mode, this option is ignored; bzip2
compression is recognized automatically on input.
-Z
- (o mode only) Compress the archive with compress-compatible compression
before writing it. In input mode, this option is ignored; compression is
recognized automatically on input.
-z
- (o mode only) Compress the archive with gzip-compatible compression before
writing it. In input mode, this option is ignored; gzip compression is
recognized automatically on input.
The cpio
utility exits 0 on success,
and >0 if an error occurs.
The following environment variables affect the execution of
cpio
:
LANG
- The locale to use. See
environ(7) for more
information.
TZ
- The timezone to use when displaying dates. See
environ(7) for more
information.
The cpio
command is traditionally used to copy file
hierarchies in conjunction with the
find(1) command. The first example
here simply copies all files from src to
dest:
find
src | cpio
-pmud
dest
By carefully selecting options to the
find(1) command and combining it
with other standard utilities, it is possible to exercise very fine control
over which files are copied. This next example copies files from
src to dest that are more
than 2 days old and whose names match a particular pattern:
find
src -mtime
+2 | grep foo[bar]
|
cpio
-pdmu
dest
This example copies files from src to
dest that are more than 2 days old and which contain
the word “foobar”:
find
src -mtime
+2 | xargs
grep
-l foobar
| cpio
-pdmu
dest
The mode options i, o, and p and the options a, B, c, d, f, l, m, r, t, u, and v
comply with SUSv2.
The old POSIX.1 standard specified that only
-i
, -o
, and
-p
were interpreted as command-line options. Each
took a single argument of a list of modifier characters. For example, the
standard syntax allows -imu
but does not support
-miu
or -i
-m
-u
, since
m and u are only modifiers to
-i
, they are not command-line options in their own
right. The syntax supported by this implementation is backwards-compatible
with the standard. For best compatibility, scripts should limit themselves
to the standard syntax.
There is no current POSIX standard for the cpio command; it appeared in
ISO/IEC 9945-1:1996 (“POSIX.1”) but was
dropped from IEEE Std 1003.1-2001
(“POSIX.1”).
The cpio, ustar, and pax interchange file formats are defined by
IEEE Std 1003.1-2001 (“POSIX.1”) for
the pax command.
The original cpio
and find
utilities were written by Dick Haight while working in AT&T's Unix Support
Group. They first appeared in 1977 in PWB/UNIX 1.0, the “Programmer's
Work Bench” system developed for use within AT&T. They were first
released outside of AT&T as part of System III Unix in 1981. As a result,
cpio
actually predates tar
,
even though it was not well-known outside of AT&T until some time later.
This is a complete re-implementation based on the
libarchive(3) library.
The cpio archive format has several basic limitations: It does not store user
and group names, only numbers. As a result, it cannot be reliably used to
transfer files between systems with dissimilar user and group numbering. Older
cpio formats limit the user and group numbers to 16 or 18 bits, which is
insufficient for modern systems. The cpio archive formats cannot support files
over 4 gigabytes, except for the “odc” variant, which can
support files up to 8 gigabytes.