cpio - copy file archives in and out
cpio -i [-bBcdfkmPrsStuvV6@] [-C bufsize] [-E file] [-
H header] [ -I file [-M message]] [-R id] [pattern...]
cpio -o [-aABcLPvV@] [-C bufsize] [-H header] [ -O file [-
cpio -p [-adlLmPuvV@] [-R id] directory
The cpio command copies files into and out of a cpio
archive. The cpio archive may span multiple volumes. The -i,
-o, and -p options select the action to be performed. The
following list describes each of the actions. These actions
are mutually exclusive.
Copy In Mode
cpio -i (copy in) extracts files from the standard input,
which is assumed to be the product of a previous cpio -o
command. Only files with names that match one of the pat-
terns are selected. See sh(1) and OPERANDS for more informa-
tion about pattern. Extracted files are conditionally copied
into the current directory tree, based on the options
described below. The permissions of the files will be those
of the previous cpio -o command. The owner and group will be
the same as the current user, unless the current user is the
super-user. If this is the case, owner and group will be the
same as those resulting from the previous cpio -o command.
Notice that if cpio -i tries to create a file that already
exists and the existing file is the same age or younger
(newer), cpio will output a warning message and not replace
the file. The -u option can be used to unconditionally
overwrite the existing file.
Copy Out Mode
cpio -o (copy out) reads a list of file path names from the
standard input and copies those files to the standard out-
put, together with path name and status information in the
form of a cpio archive. Output is padded to an 8192-byte
boundary by default or to the user-specified block size
(with the -B or -C options) or to some device-dependent
block size where necessary (as with the CTC tape).
cpio -p (pass) reads a list of file path names from the
standard input and conditionally copies those files into the
destination directory tree, based on the options described
Note: cpio assumes four-byte words.
If, when writing to a character device (-o) or reading from
a character device (-i), cpio reaches the end of a medium
(such as the end of a diskette), and the -O and -I options
are not used, cpio prints the following message:
To continue, type device/file name when ready.
To continue, you must replace the medium and type the char-
acter special device name (/dev/rdiskette for example) and
press <RETURN>. You may want to continue by directing cpio
to use a different device. For example, if you have two
floppy drives you may want to switch between them so cpio
can proceed while you are changing the floppies. Press
<RETURN> to cause the cpio process to exit.
The following options are supported:
-i (copy in) Reads an archive from the standard input and
conditionally extracts the files contained in it and
places them into the current directory tree.
-o (copy out) Reads a list of file path names from the
standard input and copies those files to the standard
output in the form of a cpio archive.
-p (pass) Reads a list of file path names from the stan-
dard input and conditionally copies those files into
the destination directory tree.
The following options can be appended in any sequence to the
-i, -o, or -p options:
-a Resets access times of input files after they have
been copied, making cpio's access invisible. Access
times are not reset for linked files when cpio -pla is
-A Appends files to an archive. The -A option requires
the -O option. Valid only with archives that are
files, or that are on floppy diskettes or hard disk
partitions. The effect on files that are linked in the
existing portion of the archive is unpredictable.
-b Reverses the order of the bytes within each word. Use
only with the -i option.
-B Blocks input/output 5120 bytes to the record. The
default buffer size is 8192 bytes when this and the -C
options are not used. -B does not apply to the -p
-c Reads or writes header information in ASCII character
form for portability. There are no UID or GID restric-
tions associated with this header format. Use this
option between SVR4-based machines, or the -H odc
option between unknown machines. The -c option implies
the use of expanded device numbers, which are only
supported on SVR4-based systems. When transferring
files between SunOS 4 or Interactive UNIX and the
Solaris 2.6 Operating environment or compatible ver-
sions, use -H odc.
Blocks input/output bufsize bytes to the record, where
bufsize is replaced by a positive integer. The default
buffer size is 8192 bytes when this and -B options are
not used. -C does not apply to the -p (pass) option.
-d Creates directories as needed.
Specifies an input file (file) that contains a list of
filenames to be extracted from the archive (one
filename per line).
-f Copies in all files except those in patterns. See
OPERANDS for a description of pattern.
Reads or writes header information in header format.
Always use this option or the -c option when the ori-
gin and the destination machines are different types.
This option is mutually exclusive with options -c and
Valid values for header are:
bar bar head and format. Used only with the -i
option ( read only).
ASCII header with expanded device numbers and an
additional per-file checksum. There are no UID
or GID restrictions associated with this header
odc ASCII header with small device numbers. This is
the IEEE/P1003 Data Interchange Standard cpio
header and format. It has the widest range of
portability of any of the header formats. It is
the official format for transferring files
between POSIX-conforming systems (see stan-
dards(5)). Use this format to communicate with
SunOS 4 and Interactive UNIX. This header format
allows UIDs and GIDs up to 262143 to be stored
in the header.
tar header and format. This is an older tar
header format that allows UIDs and GIDs up to
2097151 to be stored in the header. It is pro-
vided for the reading of legacy archives only,
that is, in conjunction with option -i.
Specifying this archive format with option -o
has the same effect as specifying the "ustar"
format: the output archive is in ustar format,
and must be read using -H ustar.
IEEE/P1003 Data Interchange Standard tar header
and format. This header format allows UIDs and
GIDs up to 2097151 to be stored in the header.
Files with UIDs and GIDs greater than the limit stated
above will be archived with the UID and GID of 60001.
To transfer a large file (8 Gb - 1 byte), the header
format can be tar|TAR, ustar|USTAR, or odc only.
Reads the contents of file as an input archive,
instead of the standard input. If file is a character
special device, and the current medium has been com-
pletely read, replace the medium and press <RETURN> to
continue to the next medium. This option is used only
with the -i option.
-k Attempts to skip corrupted file headers and I/O errors
that may be encountered. If you want to copy files
from a medium that is corrupted or out of sequence,
this option lets you read only those files with good
headers. For cpio archives that contain other cpio
archives, if an error is encountered, cpio may ter-
minate prematurely. cpio will find the next good
header, which may be one for a smaller archive, and
terminate when the smaller archive's trailer is
encountered. Use only with the -i option.
-l In pass mode, makes hard links between the source and
destination whenever possible. If the -L option is
also specified, the hard link will be to the file
referred to by the symbolic link. Otherwise, the hard
link will be to the symbolic link itself. Use only
with the -p option.
-L Follows symbolic links. If a symbolic link to a direc-
tory is encountered, archives the directory referred
to by the link, using the name of the link. Otherwise,
archives the file referred to by the link, using the
name of the link.
-m Retains previous file modification time. This option
is ineffective on directories that are being copied.
Defines a message to use when switching media. When
you use the -O or -I options and specify a character
special device, you can use this option to define the
message that is printed when you reach the end of the
medium. One %d can be placed in message to print the
sequence number of the next medium needed to continue.
Directs the output of cpio to file, instead of the
standard output. If file is a character special device
and the current medium is full, replace the medium and
type a carriage return to continue to the next medium.
Use only with the -o option.
-P Preserves ACLs. If the option is used for output,
existing ACLs are written along with other attributes,
except for extended attributes, to the standard out-
put. ACLs are created as special files with a special
file type. If the option is used for input, existing
ACLs are extracted along with other attributes from
standard input. The option recognizes the special file
type. Notice that errors will occur if a cpio archive
with ACLs is extracted by previous versions of cpio.
This option should not be used with the -c option, as
ACL support may not be present on all systems, and
hence is not portable. Use ASCII headers for portabil-
-r Interactively renames files. If the user types a car-
riage return alone, the file is skipped. If the user
types a ``.'', the original pathname will be retained.
Not available with cpio -p.
-R id Reassigns ownership and group information for each
file to user ID. (ID must be a valid login ID from
/etc/passwd.) This option is valid only for the
-s Swaps bytes within each half word.
-S Swaps halfwords within each word.
-t Prints a table of contents of the input. If any file
in the table of contents has extended attributes,
these are also listed. No files are created. -t and -V
are mutually exclusive.
-u Copies unconditionally. Normally, an older file will
not replace a newer file with the same name.
-v Verbose. Prints a list of file and extended attribute
names. When used with the -t option, the table of con-
tents looks like the output of an ls -l command (see
-V Special verbose. Prints a dot for each file read or
written. Useful to assure the user that cpio is work-
ing without printing out all file names.
-6 Processes a UNIX System Sixth Edition archive format
file. Use only with the -i option. This option is
mutually exclusive with -c and -H.
-@ Includes extended attributes in archive. By default,
cpio does not place extended attributes in the
archive. With this flag, cpio will look for extended
attributes on the files to be placed in the archive
and add them, as regular files, to the archive. The
extended attribute files go in the archive as special
files with special file types. When the -@ flag is
used with -i or -p, it instructs cpio to restore
extended attribute data along with the normal file
data. Extended attribute files can only be extracted
from an archive as part of a normal file extract.
Attempts to explicitly extract attribute records are
The following operands are supported:
A path name of an existing directory to be used as the
target of cpio -p.
Expressions making use of a pattern-matching notation
similar to that used by the shell (see sh(1)) for
filename pattern matching, and similar to regular
expressions. The following metacharacters are defined:
* Matches any string, including the empty string.
? Matches any single character.
[...] Matches any one of the enclosed characters. A
pair of characters separated by `-' matches any
symbol between the pair (inclusive), as defined
by the system default collating sequence. If the
first character following the opening `[' is a
`!', the results are unspecified.
! The ! (exclamation point) means not. For exam-
ple, the !abc* pattern would exclude all files
that begin with abc.
In pattern, metacharacters ?, *, and [...] match the slash
(/) character, and backslash (\) is an escape character.
Multiple cases of pattern can be specified and if no pattern
is specified, the default for pattern is * (that is, select
Each pattern must be enclosed in double quotes. Other-
wise, the name of a file in the current directory
might be used.
See largefile(5) for the description of the behavior of cpio
when encountering files greater than or equal to 2 Gbyte ( 2
The following examples show three uses of cpio.
Example 1: Using standard input
example% ls | cpio -oc > ../newfile
When standard input is directed through a pipe to cpio -o,
as in the example above, it groups the files so they can be
directed (>) to a single file (../newfile). The -c option
insures that the file will be portable to other machines (as
would the -H option). Instead of ls(1), you could use
find(1), echo(1), cat(1), and so on, to pipe a list of names
to cpio. You could direct the output to a device instead of
Example 2: Extracting files into directories
example% cat newfile | cpio -icd "memo/a1" "memo/b*"
In this example, cpio -i uses the output file of cpio -o
(directed through a pipe with cat), extracts those files
that match the patterns (memo/a1, memo/b*), creates direc-
tories below the current directory as needed (-d option),
and places the files in the appropriate directories. The -c
option is used if the input file was created with a portable
header. If no patterns were given, all files from newfile
would be placed in the directory.
Example 3: Copying or linking files to another directory
example% find . -depth -print | cpio -pdlmv newdir
In this example, cpio -p takes the file names piped to it
and copies or links (-l option) those files to another
directory, newdir. The -d option says to create directories
as needed. The -m option says to retain the modification
time. (It is important to use the -depth option of find(1)
to generate path names for cpio. This eliminates problems
that cpio could have trying to create files under read-only
directories.) The destination directory, newdir, must exist.
Notice that when you use cpio in conjunction with find, if
you use the -L option with cpio, you must use the -follow
option with find and vice versa. Otherwise, there will be
For multi-reel archives, dismount the old volume, mount the
new one, and continue to the next tape by typing the name of
the next device (probably the same as the first reel). To
stop, type a <RETURN> and cpio will end.
See environ(5) for descriptions of the following environment
variables that affect the execution of cpio: LC_COLLATE,
LC_CTYPE, LC_MESSAGES, LC_TIME, TZ, and NLSPATH.
cpio creates its temporary file in /var/tmp by
default. Otherwise, it uses the directory specified by
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| Availability | SUNWcsu |
| CSI | Enabled |
| Interface Stability | Stable |
ar(1), cat(1), echo(1), find(1), ls(1), setfacl(1), sh( 1),
tar(1), vold(1M), archives(4), attributes(5), environ(5),
fsattr(5), largefile(5), standards(5)
The maximum path name length allowed in a cpio archive is
determined by the header type involved. The following table
shows the proper value for each supported archive header
Header type Command line options Maximum path name length
BINARY "-o" 256
POSIX "-oH odc" 256
ASCII "-oc" 1023
CRC "-oH crc" 1023
USTAR "-oH ustar" 255
When the command line options "-o -H tar" are specified, the
archive created is of type USTAR. This means that it is an
error to read this same archive using the command line
options "-i -H tar". The archive should be read using the
command line options "-i -H ustar". The options "-i -H tar"
refer to an older tar archive format.
An error message is output for files whose UID or GID are
too large to fit in the selected header format. Use -H crc
or -c to create archives that allow all UID or GID values.
Only the super-user can copy special files.
Blocks are reported in 512-byte quantities.
If a file has 000 permissions, contains more than 0 charac-
ters of data, and the user is not root, the file will not be
saved or restored.
The inode number stored in the header
(/usr/include/archives.h) is an unsigned short, which is 2
bytes. This limits the range of inode numbers from 0 to
65535. Files which are hard linked must fall in this inode
range. This could be a problem when moving cpio archives
between different vendors' machines.
When the Volume Management daemon is running, accesses to
floppy devices through the conventional device names (for
example, /dev/rdiskette) may not succeed. See vold(1M) for
You must use the same blocking factor when you retrieve or
copy files from the tape to the hard disk as you did when
you copied files from the hard disk to the tape. Therefore,
you must specify the -B or -C option.
During -p and -o processing, cpio buffers the file list
presented on stdin in a temporary file.
Man(1) output converted with