pax - portable archive exchange

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SYNOPSIS

AVAILABILITY

pax is available with the System V software installation option. Refer to [a manual with the abbreviation INSTALL] for information on how to install optional software.

DESCRIPTION

pax reads and writes archive files which conform to the Archive/Interchange File Format specified in IEEE Std. 1003.1-1988 (POSIX.1). pax can also read, but not write, a number of other file formats in addition to those specified in the Archive/Interchange File Format description. Support for these traditional file formats, such as V7 tar.1 and System V binary cpio.1 format archives, is provided for backward compatibility and to maximize portability.

pax will also support traditional cpio and System V tar interfaces if invoked with the name cpio or tar respectively. See the paxcpio.1v or ustar.1v manual pages for more details.

directory specifies the destination directory pathname for copies when both the -r and -w options are specified. The directory must exist and be writable before the copy or and error results.

pathname is a file whose contents are used instead of the files named on the standard input. When a directory is named, all of its files and (recursively) subdirectories are copied as well.

A pattern is given in the standard shell pattern matching notation. The default if no pattern is specified is `*', which selects all files.

Combinations of the -r and -w command line arguments specify whether pax will read, write or list the contents of the specified archive, or move the specified files to another directory.

If neither the -r or -w options are given, pax will list the contents of the specified archive. In this mode, pax lists normal files one per line, hard link pathnames as

pathname == linkname

and symbolic link pathnames (if supported by the implementation) as

pathname -> linkname

where pathname is the name of the file being extracted, and linkname is the name of a file which appeared earlier in the archive.

If the -v option is specified, then pax list normal pathnames in the same format used by ls.1v with the -l option. Hard links are shown as

<ls -l listing> == linkname

and symbolic links (if supported) are shown as

<ls -l listing> -> linkname

pax is capable of reading and writing archives which span multiple physical volumes. Upon detecting an end of medium on an archive which is not yet completed, pax will prompt the user for the next volume of the archive and will allow the user to specify the location of the next volume.

When writing to an archive, the standard input is used as a list of pathnames if no pathname operands are specified. The format is one pathname per line. Otherwise, the standard input is the archive file, which is formatted according to one of the specifications in Archive/Interchange File format in POSIX.1, or some other implementation-defined format.

The user ID and group ID of the process, together with the appropriate privileges, affect the ability of pax to restore ownership and permissions attributes of the archived files. See format-reading utility in Archive/Interchange File Format in POSIX.1.

OPTIONS

-w

Write the files and directories specified by pathname to the standard output together with the pathname and status information prescribed by the archive format used. pathname refers to the files and (recursively) subdirectories of that directory. If pathname is not specified, then the standard input is read to get a list of pathnames to copy, one pathname per line. In this case, only those pathnames appearing on the standard input are copied.

-r

Read an archive file from the standard input. Only files with names that match pattern are selected for extraction. The selected files are conditionally created and copied relative to the current directory tree, subject to the options described below. By default, the owner and group of selected files will be that of the invoking process, and the permissions and modification times will be the sames as those in the archive.

The supported archive formats are automatically detected on input. The default output format is ustar, but may be overridden by the -x format option described below.

-rw

Read the files and directories named in pathname and copy them to the destination directory. A directory pathname refers to the files and (recursively) subdirectories of that directory. If pathname is not specified, the standard input is read to get a list of pathnames to copy, one pathname per line. In this case, only those pathnames appearing on the standard input are copied. The directory named by directory must exist and have the proper permissions before the copy can occur.

-a

Append the files specified by pathname to the specified archive.

-c

Complement the match sense of pattern.

-d

Intermediate directories not explicitly listed in the archive are not created. This option is ignored unless the -r option is specified.

-i

Interactively rename files. Substitutions specified by the -s option (described below) are performed before requesting the new file name from the user. A file is skipped if an empty line is entered and pax exits with an exit status of 0 if an EOF is encountered.

-l

Link files rather than copy when possible.

-m

File modification times are not retained.

-n

When -r is specified, but -w is not, the pattern arguments are treated as ordinary file names. Only the first occurrence of each of these files in the input archive is read. The pax utility exits with a zero exit status after all files in the list have been read. If one or more files in the list is not found, pax writes a diagnostic to standard error for each of the files and exits with a non-zero exit status. The file names are compared before any of the -i, -s, or -y options are applied.

-o

Restore file ownership as specified in the archive. The invoking process must have appropriate privileges to accomplish this.

-p

Preserve the access time of the input files after they have been copied.

-u

Copy each file only if it is newer than a pre-existing file with the same name. This implies the -a option.

-v

List file names as they are encountered. Produces a verbose table of contents listing on the standard output when both the -r and -w options are omitted, otherwise the file names are printed to standard error as they are encountered in the archive.

-y

Interactively prompt for the disposition of each file. Substitutions specified by -s options (described above) are performed before prompting the user for disposition. pax exits after receiving an EOF or an input line starting with the character q. Files are ignored if an input line starting with anything other than y is specified. This option cannot be used in conjunction with the -i option.

-b blocking

Block the output at blocking bytes per write to the archive file. A k suffix multiplies blocking by 1024, a b suffix multiplies blocking by 512 and a m suffix multiplies blocking by 1048576 (1 megabyte). If not specified, blocking is automatically determined on input and is ignored if the -rw option is specified.

-f archive

Specify the pathname of the input or output archive, overriding the default of the standard input for the -r option or the standard output for the -w option.

-s replstr

File names are modified according to the substitution expression using the syntax of ed.1 as shown:

-s /old/new/[gp]

Any non-null character may be used as a delimiter (a `/' is used here as an example). Multiple -s expressions may be specified; the expressions are applied in the order specified, terminating with the first successful substitution. The optional trailing g replaces the old expression each time it occurs in the source string. The optional trailing p lists successful mappings on the standard error. Files that substitute to an empty string are ignored both on input and output.

-t device

The device option argument is an implementation-defined identifier that names the input or output archive device, overriding the default of the standard input for -r and the standard output for -w.

-x format

Specifies the output archive format. The input format, which must be one of the following, is automatically determined when the -r option is used. The supported formats are:

cpio

The extended CPIO interchange format specified in Extended CPIO Format in POSIX.1.

tar

The extended TAR interchange format specified in Extended TAR Format in POSIX.1. This is the default archive format.

Only the last of multiple -f or -t options take effect.

The options -a, -c, -d, -i, -l, -p, -t, -u, and -y are provided for functional compatibility with the historical cpio and tar utilities. The option defaults were chosen based on the most common usage of these options, therefore, some of the options have meanings different than those of the historical commands.

EXAMPLES

The following command:

pax -w -f /dev/rmt0 .

copies the contents of the current directory to tape drive 0.

The commands:

mkdir newdir
cd olddir
pax -rw . newdir

copies the contents of olddir to newdir.

The command:

pax -r -s ',//*usr//*,,' -f pax.out

reads the archive pax.out with all files rooted in /usr in the archive extracted relative to the current directory.

FILES

/dev/tty

used to prompt the user for information when the -i or -y options are specified

SEE ALSO

IEEE Std. 1003.1-1988

DIAGNOSTICS

pax will terminate immediately, without processing any additional files on the command line or in the archive.

EXIT CODES

pax exits with one of the following values:

0

All files in the archive were processed successfully.

>0

pax aborted due to errors encountered during operation.

BUGS

Special permissions may be required to copy or extract special files.

For device, user ID, and group ID numbers larger than 65535 additional header records are output. These records are ignored by some historical version of cpio.1 and tar.1

The archive formats described in Archive/Interchange File Format have certain restrictions that have been carried over from historical usage. For example, there are restrictions on the length of pathnames stored in the archive.

When getting an `ls -l' style listing on tar format archives, link counts are listed as zero since the ustar archive format does not keep link count information.

AUTHOR

Mark H. Colburn
NAPS International
117 Mackubin Street, Suite 1
St. Paul, MN 55102

Sponsored by The USENIX Association for public distribution.

Created by unroff & hp-tools. © somebody (See intro for details). All Rights Reserved. Last modified 11/5/97