NAME
cpio - copy files to and from archives
SYNOPSIS
cpio {-i} [options] [pattern ...] [< archive]
cpio {-o} [options] < name-list [> archive]
cpio {-p} [options] dest-dir < name-list
DESCRIPTION
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 overriden)
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 overriden) containing
the specified items.
-p Pass-through. Read a list of filenames from standard input and
copy the files to the specified directory.
OPTIONS
Unless specifically stated otherwise, options are applicable in all
operating modes.
-0 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 (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
Read archive from or write archive to file.
-f pattern
(i mode only) Ignore files that match pattern.
--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 format
Synonym for --format.
-h, --help
Print usage information.
-I file
Read archive from file.
-i 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 and path
names containing ‘..’ in the name.
-J (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 (p mode only) Create links from the target directory to the
original files, instead of copying.
-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.
-m (i and p modes) Set file modification time on created files to
match those in the source.
-n (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 Output mode. See above for description.
-p 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]
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 (i mode only) List the contents of the archive to stdout; do not
restore the contents to disk.
-u (i and p modes) Unconditionally overwrite existing files.
Ordinarily, an older file will not overwrite a newer file on
disk.
-v 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.
ENVIRONMENT
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.
EXIT STATUS
The cpio utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
The cpio command is traditionally used to copy file heirarchies 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
COMPATIBILITY
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.
SEE ALSO
bzip2(1), tar(1), gzip(1), mt(1), pax(1), libarchive(3), cpio(5),
libarchive-formats(5), tar(5)
STANDARDS
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.
HISTORY
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.
BUGS
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.