Man Pages

---

Back to Software Index  Manpage Top Level

Name

Synopsis

Availability

Description

Modes of Operations

The action to be taken depends on the presence of the -r and -w options. The four combinations of -r and -w are referred to as the four modes of operation: list, read, write, and copy modes, corresponding respectively to the four forms shown in the SYNOPSIS.

list

In list mode (when neither -r nor -w are specified), pax writes the names of the members of the archive file read from the standard input, with path names matching the specified patterns, to standard output. If a named file is of type directory, the file hierarchy rooted at that file will be written out as well.

read

In read mode (when -r is specified, but -w is not), pax extracts the members of the archive file read from the standard input, with path names matching the specified patterns. If an extracted file is of type directory, the file hierarchy rooted at that file will be extracted as well. The extracted files is created relative to the current file hierarchy.

The ownership, access and modification times,

and file mode of the restored files are discussed under the -p option.

write

In write mode (when -w is specified, but -r is not), pax writes the contents of the file operands to the standard output in an archive format. If no file operands are specified, a list of files to copy, one per line, will be read from the standard input. A file of type directory will include all of the files in the file hierarchy rooted at the file.

copy

In copy mode (when both -r and -w are specified), pax copies the file operands to the destination directory.

If no

file operands are specified, a list of files to copy, one per line, will be read from the standard input. A file of type directory will include all of the files in the file hierarchy rooted at the file.

The effect of the copy is as if the copied files

were written to an archive file and then subsequently extracted, except that there may be hard links between the original and the copied files. If the destination directory is a subdirectory of one of the files to be copied, the results are unspecified. It is an error if directory doesn’t to exist, is not writable by the user, or is not a directory.

In read or copy modes, if intermediate directories are necessary to extract an archive member, pax will perform actions equivalent to the mkdir(2) function, called with the following arguments:

• the intermediate directory used as the path argument
• the octal value of 777 or rwx (read, write, and execute permissions) as the mode argument (see chmod(1) ).

If any specified pattern or file operands are not matched by at least one file or archive member, pax will write a diagnostic message to standard error for each one that did not match and exit with a non-zero exit status.

The supported archive formats are automatically detected on input. The default output archive format is tar(1) .

If the selected archive format supports the specification of linked files, it is an error if these files cannot be linked when the archive is extracted. Any of the various names in the archive that represent a file can be used to select the file for extraction.

Options

-r

Read an archive file from standard input.

-w

Write files to the standard output in the specified archive format.

-a

Append files to the end of the archive. This option will not work for some archive devices, such as 1/4-inch streaming tapes and 8mm tapes.

-b blocksize

Block the output at a positive decimal integer number of bytes per write to the archive file. Devices and archive formats may impose restrictions on blocking. Blocking is automatically determined on input. Portable applications must not specify a blocksize value larger than 32256. Default blocking when creating archives depends on the archive format. (See the -x option below.)

-c

Match all file or archive members except those specified by the pattern or file operands.

-d

Cause files of type directory being copied or archived or archive members of type directory being extracted to match only the file or archive member itself and not the file hierarchy rooted at the file.

-f archive

Specify the path name of the input or output archive, overriding the default standard input (in list or read modes) or standard output (write mode).

-i

Interactively rename files or archive members. For each archive member matching a pattern operand or file matching a file operand, a prompt will be written to the file /dev/tty. The prompt will contain the name of the file or archive member. A line will then be read from /dev/tty. If this line is blank, the file or archive member will be skipped. If this line consists of a single period, the file or archive member will be processed with no modification to its name. Otherwise, its name will be replaced with the contents of the line. The pax command will immediately exit with a non-zero exit status if end-of-file is encountered when reading a response or if /dev/tty cannot be opened for reading and writing.

-k

Prevent the overwriting of existing files.

-l

Link files. In copy mode, hard links will be made between the source and destination file hierarchies whenever possible.

-n

Select the first archive member that matches each pattern operand. No more than one archive member will be matched for each pattern (although members of type directory will still match the file hierarchy rooted at that file).

-o options

Reserved for special format-specific options.

-p string

Specify one or more file characteristic options (privileges). The string option-argument must be a string specifying file characteristics to be retained or discarded on extraction. The string consists of the specification characters a, e, m, o and p. Multiple characteristics can be concatenated within the same string and multiple -p options can be specified. The meaning of the specification characters are as follows:

a

Do not preserve file access times.

e

Preserve the user ID, group ID, file mode bits, access time, and modification time.

m

Do not preserve file modification times.

o

Preserve the user ID and group ID.

p

Preserve the file mode bits. Other, implementation-dependent file-mode attributes may be preserved.

In the preceding list, ‘‘preserve’’ indicates

that an attribute stored in the archive will be given to the extracted file, subject to the permissions of the invoking process; otherwise, the attribute will be determined as part of the normal file creation action.

If neither the

e nor the o specification character is specified, or the user ID and group ID are not preserved for any reason, pax will not set the setuid and setgid bits of the file mode.

If the preservation of any of these items fails for any reason,

pax will write a diagnostic message to standard error. Failure to preserve these items will affect the final exit status, but will not cause the extracted file to be deleted.

If file-characteristic letters in any of the

string option-arguments are duplicated or conflict with each other, the ones given last will take precedence. For example, if -p eme is specified, file modification times will be preserved.

-s replstr

Modify file or archive member names named by pattern or file operands according to the substitution expression replstr, which is based on the ed(1) s (substitution) command, using the regular expression syntax on the regex(5) manual page. The concepts of ‘‘address’’ and ‘‘line’’ are meaningless in the context of the pax command, and must not be supplied. The format is:

-s / old/new/ [ gp ]

where, as in

ed, old is a basic regular expression and new can contain an ampersand (&) or a \n backreference, where n is a digit. The old string also is permitted to contain newline characters.

Any non-null character can be used as a delimiter

( / "" shown here). Multiple -s expressions can be specified; the expressions will be applied in the order specified, terminating with the first successful substitution. The optional trailing g is as defined in the ed command. The optional trailing p causes successful substitutions to be written to standard error. File or archive member names that substitute to the empty string are ignored when reading and writing archives.

-t

Cause the access times of the archived files to be the same as they were before being read by pax.

-u

Ignore files that are older (having a less recent file modification time) than a pre-existing file or archive member with the same name.

read mode

an archive member with the same name as a file in the file system will be extracted if the archive member is newer than the file.

write mode

an archive file member with the same name as a file in the file system will be superseded if the file is newer than the archive member.

copy mode

the file in the destination hierarchy will be replaced by the file in the source hierarchy or by a link to the file in the source hierarchy if the file in the source hierarchy is newer.

-v

In list mode, produce a verbose table of contents (see Standard Output). Otherwise, write archive member path names to standard error (see Standard Error).

-x format

Specify the output archive format. The pax command recognizes the following formats:

cpio

The extended cpio interchange format; see the IEEE 1003.1(1990) specifications. The default blocksize for this format for character special archive files is 5120. Implementations support all blocksize values less than or equal to 32256 that are multiples of 512.

This archive format allows files with UIDs and GIDs up to 262143 to be

stored in the archive. Files with UID s and GID s greater than this value will be archived with the UID and GID of 60001.

ustar

The extended tar interchange format; see the IEEE 1003.1(1990) specifications. The default blocksize for this format for character special archive files is 10240. Implementations support all blocksize values less than or equal to 32256 that are multiples of 512.

Any attempt to append to an archive file in a format different

from the existing archive format will cause pax to exit immediately with a non-zero exit status.

This archive format allows files with UIDs and GIDs up to 2097151

to be stored in the archive. Files with UID s and GID s greater than this value will be archived with the UID and GID of 60001.

-X

When traversing the file hierarchy specified by a path name, pax will not descend into directories that have a different device ID (st_dev, see stat(2) ).

The options that operate on the names of files or archive members (-c, -i, -n, -s, -u and -v) interact as follows. In read mode, the archive members are selected based on the user-specified pattern operands as modified by the -c, -n and -u options. Then, any -s and -i options will modify, in that order, the names of the selected files. The -v option will write names resulting from these modifications.

In write mode, the files are selected based on the user-specified path names as modified by the -n and -u options. Then, any -s and -i options will, in that order, modify the names of these selected files. The -v option will write names resulting from these modifications.

If both the -u and -n options are specified, pax does not consider a file selected unless it is newer than the file to which it is compared.

Operands

directory

The destination directory path name for copy mode.

file

A path name of a file to be copied or archived.

pattern

A pattern matching one or more path names of archive members. A pattern must conform to the pattern matching notation found on the fnmatch(5) manual page. The default, if no pattern is specified, is to select all members in the archive.

Output

Standard Output

In list mode, the table of contents of the selected archive members will be written to standard output using the following format:

"%s\n" <pathname>

If the -v option is specified in list mode, the table of contents of the selected archive members will be written to standard output using the following formats:

For path names representing hard links to previous members of the archive:

"%s*D ==*D %s\n" <ls -l listing>, linkname

For all other path names:

<pathname> "%s\n" <ls -l listing>

where <ls -l listing> is the format specified by the ls command with the -l option. When writing path names in this format, it is unspecified what is written for fields for which the underlying archive format does not have the correct information, although the correct number of blank-character-separated fields will be written.

In list mode, standard output will not be buffered more than a line at a time.

Standard Error

"%s\n" <pathname>

These path names will be written as soon as processing is begun on the file or archive member, and will be flushed to standard error. The trailing newline character, which will not be buffered, will be written when the file has been read or written.

If the -s option is specified, and the replacement string has a trailing p, substitutions will be written to standard error in the following format:

"%s*D >>*D %s\n" <original pathname>, <new pathname>

In all operating modes of pax, optional messages of unspecified format concerning the input archive format and volume number, the number of files, blocks, volumes and media parts as well as other diagnostic messages may be written to standard error.

In all formats, for both standard output and standard error, it is unspecified how non-printable characters in path names or linknames are written.

Errors

If the extraction of a file from an archive is prematurely terminated by a signal or error, pax may have only partially extracted the file or (if the -n option was not specified) may have extracted a file of the same name as that specified by the user, but which is not the file the user wanted. Additionally, the file modes of extracted directories may have additional bits from the read, write, execute mask set as well as incorrect modification and access times.

Usage

-p e

‘‘Preserve everything’’. This would be used by the historical superuser, someone with all the appropriate privileges, to preserve all aspects of the files as they are recorded in the archive. The e flag is the sum of o and p, and other implementation-dependent attributes.

-p p

‘‘Preserve’’ the file mode bits. This would be used by the user with regular privileges who wished to preserve aspects of the file other than the ownership. The file times are preserved by default, but two other flags are offered to disable these and use the time of extraction.

Examples

example pax -w -f /dev/rmt/1m .

copies the contents of the current directory to tape drive 1, medium density (assuming historical System V device naming procedures. The historical BSD device name would be /dev/rmt9).

The following commands:

example% mkdir newdir example% pax -rw olddir newdir

copy the olddir directory hierarchy to newdir.

example "pax -r -s ’,^//*usr//*,,’ -f a.pax"

Environment

LC_COLLATE

Determine the locale for the behaviour of ranges, equivalence classes, and multi-character collating elements used in the pattern matching expressions for the pattern operand, the basic regular expression for the -s option, and the extended regular expression defined for the yesexpr locale keyword in the LC_MESSAGES category.

Exit Status

1. All files were processed successfully.
   >0
   An error occurred.

   See Also

   chmod(1) , cpio(1) , ed(1) , tar(1) , mkdir(2) , stat(2) , environ(5) , fnmatch(5) , regex(5)

   ---

   Table of Contents

   • Name
   • Synopsis
   • Availability
   • Description
   • Modes of Operations
   • Options
   • Operands
   • Output
   • Standard Output
   • Standard Error
   • Errors
   • Usage
   • Examples
   • Environment
   • Exit Status
   • See Also