CPIO(C) UNIX System V
Name
cpio - copy file archives in and out
Syntax
cpio -o[acBvV] [-C bufsize] [[-O file] [-K volumesize] [-M
message]]
cpio -i[BcdmrtTuvVfsSb6k] [-C bufsize] [[-I file] [-K
volumesize] [-M message]] [pattern ...]
cpio -p[adlmuvV] directory
Description
cpio -o (copy out) reads the standard input to obtain a list
of path names and copies those files onto the standard
output together with path name and status information.
Output is padded to a 512-byte boundary by default.
cpio -i (copy in) extracts files from the standard input,
which is assumed to be the product of a previous cpio -o.
Only files with names that match patterns are selected.
patterns are regular expressions given in the filename-
generating notation of sh(C). In patterns, metacharacters
?, *, and [...] match the slash (/) character, and
backslash (\) is an escape character. A ! metacharacter
means not. (For example, the !abc* pattern would exclude
all files that begin with abc.) Multiple patterns may be
specified and if no patterns are specified, the default for
patterns is * (i.e., select all files). Each pattern must
be enclosed in double quotes otherwise the name of a file in
the current directory is used. Extracted files are
conditionally created and copied into the current directory
tree based upon the options described below. The
permissions of the files will be those of the previous cpio
-o . The owner and group of the files will be that of the
current user unless the user is super-user, which causes
cpio to retain the owner and group of the files of the
previous cpio -o . NOTE: If cpio -i tries to create a file
that already exists and the existing file is the same age or
newer, cpio will output a warning message and not replace
the file. (The -u option can be used to unconditionally
overwrite the existing file.)
cpio -p (pass) reads the standard input to obtain a list of
path names of files that are conditionally created and
copied into the destination directory tree based upon the
options described below. Archives of text files created by
cpio are portable between implementations of UNIX System V.
The meanings of the available options are:
-a Reset access times of input files after they have been
copied. Access times are not reset for linked files
when cpio -pla is specified.
-b Reverse the order of the bytes within each word. Use
only with the -i option.
-B Input/output is to be blocked 5,120 bytes to the
record. The default buffer size is 512 bytes when this
and the -C options are not used. (-B does not apply to
the pass option; -B is meaningful only with data
directed to or from a character-special device, e.g.,
/dev/rdsk/f0q15dt.)
-c Write header information in ASCII character form for
portability. Always use this option when origin and
destination machines are different types.
-C bufsize
Input/output is to be blocked bufsize bytes to the
record, where bufsize is replaced by a positive
integer. The default buffer size is 512 bytes when
this and -B options are not used. (-C does not apply
to the pass option; -C is meaningful only with data
directed to or from a character-special device, e.g.,
/dev/rmt/c0s0.) When used with the -K option, bufsize
is forced to be a 1K multiple.
-d directories are to be created as needed.
-f Copy in all files except those in patterns. (See the
paragraph on cpio -i for a description of patterns.)
-I file
Read the contents of file as input. If file is a
character-special device, when the first medium is
full, replace the medium and type a carriage return to
continue to the next medium. Use only with the -i
option.
-k Attempt 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
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.) Used only with the -i option.
-l Whenever possible, link files rather than copying them.
Usable only with the -p option.
-m Retain previous file modification time. This option is
ineffective on directories that are being copied.
-K volumesize
Specifies the size of the media volume. Must be in 1K
blocks. For example, a 1.2 MB floppy disk has a
volumesize of 1200. Must include the -C option with a
bufsize multiple of 1K.
-M message
Define 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 the message to print
the sequence number of the next medium needed to
continue.
-O file
Direct the output of cpio to file. If file is a
character-special device, when the first medium is
full, replace the medium and type a carriage return to
continue to the next medium. Use only with the -o
option.
-r Interactively rename files. If the user types a null
line, the file is skipped. If the user types a ".",
the original pathname will be copied. (Not available
with cpio -p.)
-s swap bytes within each half word. Use only with the -i
option.
-S Swap halfwords within each word. Use only with the -i
option.
-T Truncate long filenames to 14 characters. Use only
with the -i option.
-t Print a table of contents of the input. No files are
created.
-u Copy unconditionally (normally, an older file will not
replace a newer file with the same name).
-v verbose: causes a list of file names to be printed.
When used with the -t option, the table of contents
looks like the output of an ls -l command [see ls(C)].
-V SpecialVerbose: print a dot for each file seen.
Useful to assure the user that cpio is working without
printing out all file names.
-6 Process an old (i.e., UNIX System Sixth Edition format)
file. Use only with the -i option.
NOTE: cpio assumes 4-byte words.
If cpio reaches end of medium (end of a diskette for
example) when writing to (-o) or reading from (-i) a
character-special device, and -O and -I are not used, cpio
will print the message:
If you want to go on, type device/file name when ready.
To continue, you must replace the medium and type the
character-special device name (/dev/rdsk/f0q15dt for
example) and a carriage 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. (A carriage return alone causes the cpio process
to exit.)
Examples
The following examples show three uses of cpio.
When standard input is directed through a pipe to cpio -o,
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. Instead of ls(C), you could
use find(C), echo(C), cat(C), etc., to pipe a list of names
to cpio. You could direct the output to a device instead of
a file.
ls | cpio -oc >../newfile
cpio -i uses the output file of cpio -o (directed through a
pipe with cat in the example), 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 directories. The -c
option is used when the file is created with a portable
header. If no patterns were given, all files from newfile
would be placed in the directory.
cat newfile | cpio -icd "memo/a1" "memo/b*"
cpio -p takes the file names piped to it and copies or links
(-l option) those files to another directory on your machine
(newdir in the example). The -d options says to create
directories as needed. The -m option says retain the
modification time. [It is important to use the -depth
option of find(C) to generate path names for cpio. This
eliminates problems cpio could have trying to create files
under read-only directories.]
find . -depth -print | cpio -pdlmv newdir
See Also
cat(C), echo(C), find(C), ls(C), tar(C), cpio(F)
Notes
1) Path names are restricted to 256 characters.
2) Only the super-user can copy special files.
3) Blocks are reported in 512-byte quantities.
4) 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.
Standards Conformance
cpio is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
and The X/Open Portability Guide II of January 1987.
(printed 4/27/90) CPIO(C)