NAME

cpio − copy file archives in and out

SYNOPSIS

cpio −i[bBcdfkmrsStuvV6] [−C size] [−E file] [−H hdr] [−I file [−M message]] [−R ID]] [pattern ...]

cpio −o[aABcLvV] [−C size] [−H hdr] [−O file [−M message]]

cpio −p[adlLmuvV] [−R ID]] directory

DESCRIPTION

The −i, −o, and −p options select the action to be performed.  The following list describes each of the actions (which are mutually exclusive). 

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(1).  In patterns, meta-characters ?, ∗, and [...] match the slash (/) character, and backslash (\) is an escape character.  A ! meta-character 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 might be used.  Extracted files are conditionally created and 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.  Owner and group permissions will be the same as the current user unless the current user is super-user.  If this is true, owner and group permissions will be the same as those resulting from 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 younger (newer), cpio will output a warning message and not replace the file.  (The −u option can be used to overwrite, unconditionally, the existing file.) 

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 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 the standard input to obtain a list of path names of files that are conditionally created and copied into the destination directory tree based on the options described below. 

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 (mutually exclusive with −m). 

−A Append 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 slices. 

−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/rmt/ctape1.) 

−c Read or write header information in ASCII character form.  The −c option implies expanded device numbers.  This option is mutually exclusive with −H and −6. 

−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/ctape1.) 

−d Directories are to be created as needed. 

−E file
Specify an input file (file) that contains a list of filenames to be extracted from the archive (one filename per line). 

−f Copy in all files except those in patterns. (See the paragraph on cpio −i for a description of patterns.) 

−H hdr
Read or write header information in hdr format.  This option should be used when the origin and destination machines are different types.  (mutually exclusive with −c and −6).  Valid values for hdr are:
crc or CRC − ASCII header with expanded device numbers and an additional per-file checksum
ustar or USTAR − IEEE/P1003.1 Data Interchange Standard tar header and format
tar or TAR − tar header and format
odc − ASCII header with small device numbers, IEEE/P1003.1 Data Interchange Standard cpio header and format. 
See the NOTES section for additional information. 

−I file Read the contents of file as an input archive.  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 −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.) 

−L Follow symbolic links. The default is not to follow symbolic links. 

−m Retain previous file modification time.  This option is ineffective on directories that are being copied (mutually exclusive with −a). 

−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 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 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. 

−r Interactively rename files.  If the user types a carriage return alone, the file is skipped.  If the user types a “.” the original pathname will be retained.  (Not available with cpio −p.) 

−R ID
Reassign 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-user. 

−s Swap bytes within each half word. 

−S Swap halfwords within each word. 

−t Print a table of contents of the input.  No files are created (mutually exclusive with −V). 

−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(1)].  See the NOTES section for additional information. 

−V Special Verbose: print a dot for each file read or written.  Useful to assure the user that cpio is working without printing out all file names. 

−6 Process a UNIX System Sixth Edition archive format file.  Use only with the −i option (mutually exclusive with −c and −H)). 

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 aren’t used, cpio will print the following 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/rmt/ctape1 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.  (Simply pressing RETURN 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 (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 file. 

ls │ cpio −oc > ../newfile

cpio −i uses the output file of cpio −o (directed through a pipe with cat in the example below), 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 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. 

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 (newdir in the example below).  The −d option says to create directories as needed.  The −m option says retain the modification time.  (It is important to use the −depth option of find(1) to generate path names for cpio.  This eliminates problems cpio could have trying to create files under read-only directories.)  The destination directory, newdir, must exist. 

find . −depth −print │ cpio −pdlmv newdir

Note that when you use cpio in conjunction with find, if you use the −L option with cpio then you must use the −follow option with find and vice versa.  Otherwise there will be undesirable results. 

SEE ALSO

ar(1), cat(1), echo(1), find(1), ls(1), tar(1), stat(4), archives(4). 

NOTES

An archive created with the −c option on a Release 4 system cannot be read on System V Release 3.2 systems, or earlier.  The −H odc header in Release 4 is equivalent to the −c header in earlier System V Releases. 

The following table illustrates important capabilities of the supported archive formats.  In the table, support for expanded data types indicates that the format can accommodate all of the fields as returned by R4 stat(2). 
 

If support for expanded data types is not present, cpio will fail with an "Old format cannot support expanded types" error under the following circumstances.  (The st_∗ fields are the values returned by R4 stat(2) when a file is being processed by cpio)

o The st_uid, st_gid or st_mode field exceeds USHRT_MAX (65535). 

o More than 32766 unique st_dev fields have been encountered. 

o More than 65534 unique st_ino fields have been encountered for any single device. 

o The st_rdev field contains a minor number greater than 255 or a major number greater than 127. 

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. 

When the -tv option is used for a TAR or USTAR input archive, an ’L’ in the type field indicates that the file is a hard link to another file.  The name of the file linked to is also printed. 

INTERNATIONAL FUNCTIONS

cpio can process files containing characters from supplementary code sets.  In pattern processing using metacharacters, matching is performed on characters, not bytes. 

message with the -M option can include characters from supplementary code sets. 

  —  Essential Utilities