cpio(1) User Commands cpio(1)
cpio - copy file archives in and out
cpio -i [-bBcdfkmPrsStuvV6@] [-C bufsize] [-E file] [-H header] [ -I
[-M message]] [-R id] [pattern...]
cpio -o [-aABcLPvV@] [-C bufsize] [-H header] [ -O file [-M message]]
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 patterns are selected. See sh(1) and
OPERANDS for more information about pattern. Extracted files are condi-
tionally copied into the current directory tree, based on the options
described below. The permissions of the files will be those of the pre-
vious cpio -o command. The owner and group will be the same as the cur-
rent 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 pre-
vious 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
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 output, 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 below.
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 fol-
To continue, type device/file name when ready.
To continue, you must replace the medium and type the character special
device name (/dev/rdiskette for example) and press <<RETURN>>. You may
want to continue by directing cpio to use a different device. For exam-
ple, 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
-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 speci-
-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 sup-
ported on SVR4-based systems. When transferring files
between SunOS 4 or Interactive UNIX and the Solaris 2.6
Operating environment or compatible versions, use -H
-C bufsize 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.
-E file Specifies an input file (file) that contains a list of
filenames to be extracted from the archive (one file-
name per line).
-f Copies in all files except those in patterns. See OPER-
ANDS for a description of pattern.
-H header Reads or writes header information in header format.
Always use this option or the -c option when the origin
and the destination machines are different types. This
option is mutually exclusive with options -c and -6.
Valid values for header are:
bar bar head and format. Used only with the
-i option ( read only).
crc | CRC ASCII header with expanded device num-
bers and an additional per-file check-
sum. There are no UID or GID restric-
tions associated with this header for-
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 offi-
cial format for transferring files
between POSIX-conforming systems (see
standards(5)). Use this format to com-
municate with SunOS 4 and Interactive
UNIX. This header format allows UIDs
and GIDs up to 262143 to be stored in
tar | TAR 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 provided 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 speci-
fying the "ustar" format: the output
archive is in ustar format, and must be
read using -H ustar.
ustar | USTAR IEEE/P1003 Data Interchange Standard
tar header and format. This header for-
mat 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.
-I file 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 completely
read, replace the medium and press <<RETURN>> to continue
to the next medium. This option is used only with the
-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 head-
ers. For cpio archives that contain other cpio ar-
chives, if an error is encountered, cpio may terminate
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
-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, ar-
chives 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.
-M message Defines a message to use when switching media. When you
use the -O or -I options and specify a character spe-
cial device, you can use this option to define the mes-
sage 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.
-O file 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 output.
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 portability.
-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 super-
-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
-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 working
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 mutu-
ally 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 explic-
itly extract attribute records are ignored.
The following operands are supported:
directory A path name of an existing directory to be used as the
target of cpio -p.
pattern Expressions making use of a pattern-matching notation
similar to that used by the shell (see sh(1)) for file-
name pattern matching, and similar to regular expres-
sions. The following metacharacters are defined:
* Matches any string, including the empty
? 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 unspeci-
! 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 all files).
Each pattern must be enclosed in double quotes. Other-
wise, the name of a file in the current directory might
See largefile(5) for the description of the behavior of cpio when
encountering files greater than or equal to 2 Gbyte ( 2**31 bytes).
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 a
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 directories below the current directory as
needed (-d option), and places the files in the appropriate directo-
ries. The -c option is used if the input file was created with a porta-
ble 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 directo-
ries.) 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 undesirable results.
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.
TMPDIR cpio creates its temporary file in /var/tmp by default.
Otherwise, it uses the directory specified by TMPDIR.
The following exit values are returned:
0 Successful completion.
>>0 An error occurred.
See attributes(5) for descriptions of the following attributes:
tab() allbox; cw(2.750000i)| cw(2.750000i) lw(2.750000i)|
lw(2.750000i). ATTRIBUTE TYPEATTRIBUTE VALUE AvailabilitySUNWcsu
CSIEnabled Interface StabilityStable
ar(1), cat(1), echo(1), find(1), ls(1), pax(1), setfacl(1), sh( 1),
tar(1), vold(1M), archives(4), attributes(5), environ(5), fsattr(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 type.
tab(); lw(1.833333i) lw(1.833333i) lw(1.833333i). Header typeCommand
line optionsMaximum 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 characters 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 num-
bers 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 further details.
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
During -p and -o processing, cpio buffers the file list presented on
stdin in a temporary file.
The new pax(1) format, with a command that supports it (for example,
pax , tar, or cpio), should be used for large files. The cpio command
is no longer part of the current POSIX standard and is deprecated in
favor of pax.
SunOS 5.10 12 Mar 2004 cpio(1)