Originální popis anglicky:
pax - portable archive interchange
Návod, kniha: POSIX Programmer's Manual
pax [-cdnv][-H|-L][-f
archive ][-s
replstr]...[pattern
...]
pax -r
[-cdiknuv][-H|-L][-f
archive][-o
options
]...[-p
string ]...
[-s
replstr]
...[pattern...]
pax -w
[-dituvX][-H|-L][-b
blocksize][[-a][-f
archive][-o
options ]...
[-s
replstr]...
[-x
format][file...]
pax -r -w
[-diklntuvX][-H|-L
][-p
string]...[-s
replstr]...
[file ...]
directory
The
pax utility shall read, write, and write lists of the members of
archive files and copy directory hierarchies. A variety of archive formats
shall be supported; see the
-x format option.
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 section.
- list
- In list mode (when neither -r nor -w
are specified), pax shall write the names of the members of the
archive file read from the standard input, with pathnames matching the
specified patterns, to standard output. If a named file is of type
directory, the file hierarchy rooted at that file shall be listed as
well.
- read
- In read mode (when -r is specified, but
-w is not), pax shall extract the members of the archive
file read from the standard input, with pathnames matching the specified
patterns. If an extracted file is of type directory, the file hierarchy
rooted at that file shall be extracted as well. The extracted files shall
be created performing pathname resolution with the directory in which
pax was invoked as the current working directory.
If an attempt is made to extract a directory when the directory already exists,
this shall not be considered an error. If an attempt is made to extract a FIFO
when the FIFO already exists, this shall not be considered an error.
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 shall write 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, shall be
read from the standard input. A file of type directory shall 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 shall copy the file operands to the
destination directory.
If no
file operands are specified, a list of files to copy, one per line,
shall be read from the standard input. A file of type directory shall include
all of the files in the file hierarchy rooted at the file.
The effect of the
copy shall be 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. If the destination directory is a file of a type not defined by
the System Interfaces volume of IEEE Std 1003.1-2001, the
results are implementation-defined; otherwise, it shall be an error for the
file named by the
directory operand not to exist, not be writable by
the user, or not be a file of type directory.
In
read or
copy modes, if intermediate directories are necessary
to extract an archive member,
pax shall perform actions equivalent to
the
mkdir() function defined in the System Interfaces volume of
IEEE Std 1003.1-2001, called with the following arguments:
- *
- The intermediate directory used as the path
argument
- *
- The value of the bitwise-inclusive OR of S_IRWXU, S_IRWXG,
and S_IRWXO as the mode argument
If any specified
pattern or
file operands are not matched by at
least one file or archive member,
pax shall write a diagnostic message
to standard error for each one that did not match and exit with a non-zero
exit status.
The archive formats described in the EXTENDED DESCRIPTION section shall be
automatically detected on input. The default output archive format shall be
implementation-defined.
A single archive can span multiple files. The
pax utility shall
determine, in an implementation-defined manner, what file to read or write as
the next file.
If the selected archive format supports the specification of linked files, it
shall be an error if these files cannot be linked when the archive is
extracted. For archive formats that do not store file contents with each name
that causes a hard link, if the file that contains the data is not extracted
during this
pax session, either the data shall be restored from the
original file, or a diagnostic message shall be displayed with the name of a
file that can be used to extract the data. In traversing directories,
pax shall detect infinite loops; that is, entering a previously visited
directory that is an ancestor of the last file visited. When it detects an
infinite loop,
pax shall write a diagnostic message to standard error
and shall terminate.
The
pax utility shall conform to the Base Definitions volume of
IEEE Std 1003.1-2001, Section 12.2, Utility Syntax Guidelines,
except that the order of presentation of the
-o,
-p, and
-s options is significant.
The following options shall be supported:
- -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. It is
implementation-defined which devices on the system support appending.
Additional file formats unspecified by this volume of
IEEE Std 1003.1-2001 may impose restrictions on
appending.
- -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 shall be automatically
determined on input. Conforming applications shall 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 or listed to match only
the file or archive member itself and not the file hierarchy rooted at the
file.
- -f archive
- Specify the pathname of the input or output archive,
overriding the default standard input (in list or read
modes) or standard output ( write mode).
- -H
- If a symbolic link referencing a file of type directory is
specified on the command line, pax shall archive the file hierarchy
rooted in the file referenced by the link, using the name of the link as
the root of the file hierarchy. Otherwise, if a symbolic link referencing
a file of any other file type which pax can normally archive is
specified on the command line, then pax shall archive the file
referenced by the link, using the name of the link. The default behavior
shall be to archive the symbolic link itself.
- -i
- Interactively rename files or archive members. For each
archive member matching a pattern operand or file matching a
file operand, a prompt shall be written to the file
/dev/tty. The prompt shall contain the name of the file or archive
member, but the format is otherwise unspecified. A line shall then be read
from /dev/tty. If this line is blank, the file or archive member
shall be skipped. If this line consists of a single period, the file or
archive member shall be processed with no modification to its name.
Otherwise, its name shall be replaced with the contents of the line. The
pax utility shall 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.
The results of extracting a hard link to a file that has been renamed during
extraction are unspecified.
- -k
- Prevent the overwriting of existing files.
- -l
- (The letter ell.) In copy mode, hard links shall be
made between the source and destination file hierarchies whenever
possible. If specified in conjunction with -H or -L, when a
symbolic link is encountered, the hard link created in the destination
file hierarchy shall be to the file referenced by the symbolic link. If
specified when neither -H nor -L is specified, when a
symbolic link is encountered, the implementation shall create a hard link
to the symbolic link in the source file hierarchy or copy the symbolic
link to the destination.
- -L
- If a symbolic link referencing a file of type directory is
specified on the command line or encountered during the traversal of a
file hierarchy, pax shall archive the file hierarchy rooted in the
file referenced by the link, using the name of the link as the root of the
file hierarchy. Otherwise, if a symbolic link referencing a file of any
other file type which pax can normally archive is specified on the
command line or encountered during the traversal of a file hierarchy,
pax shall archive the file referenced by the link, using the name
of the link. The default behavior shall be to archive the symbolic link
itself.
- -n
- Select the first archive member that matches each
pattern operand. No more than one archive member shall be matched
for each pattern (although members of type directory shall still match the
file hierarchy rooted at that file).
- -o options
- Provide information to the implementation to modify the
algorithm for extracting or writing files. The value of options
shall consist of one or more comma-separated keywords of the form:
keyword[[:]=value][,keyword[[:]=value], ...]
Some keywords apply only to certain file formats, as indicated with each
description. Use of keywords that are inapplicable to the file format being
processed produces undefined results.
Keywords in the
options argument shall be a string that would be a valid
portable filename as described in the Base Definitions volume of
IEEE Std 1003.1-2001, Section 3.276, Portable Filename Character
Set.
- Note:
Keywords are not expected to be filenames,
merely to follow the same character composition rules as portable
filenames.
Keywords can be preceded with white space. The
value field shall consist
of zero or more characters; within
value, the application shall precede
any literal comma with a backslash, which shall be ignored, but preserves the
comma as part of
value. A comma as the final character, or a comma
followed solely by white space as the final characters, in
options
shall be ignored. Multiple
-o options can be specified; if keywords
given to these multiple
-o options conflict, the keywords and values
appearing later in command line sequence shall take precedence and the earlier
shall be silently ignored. The following keyword values of
options
shall be supported for the file formats as indicated:
- delete=pattern
(Applicable only to the
-x pax format.) When used in
write
or
copy mode,
pax shall omit from extended header records that
it produces any keywords matching the string pattern. When used in
read
or
list mode,
pax shall ignore any keywords matching the string
pattern in the extended header records. In both cases, matching shall be
performed using the pattern matching notation described in
Patterns
Matching a Single Character and
Patterns Matching Multiple
Characters . For example:
would suppress security-related information. See pax Extended Header for
extended header record keyword usage.
- exthdr.name=string
(Applicable only to the
-x pax format.) This keyword allows user
control over the name that is written into the
ustar header blocks for
the extended header produced under the circumstances described in pax Header
Block . The name shall be the contents of
string, after the following
character substitutions have been made:
| string |
|
| Includes: |
Replaced By: |
| %d |
The directory name of the file, equivalent to the result of the
dirname utility on the translated pathname. |
| %f |
The filename of the file, equivalent to the result of the
basename utility on the translated pathname. |
| %p |
The process ID of the pax process. |
| %% |
A '%' character. |
Any other
'%' characters in
string produce undefined results.
If no
-o exthdr.name= string is specified,
pax shall
use the following default value:
- globexthdr.name=string
(Applicable only to the
-x pax format.) When used in
write
or
copy mode with the appropriate options,
pax shall create
global extended header records with
ustar header blocks that will be
treated as regular files by previous versions of
pax. This keyword
allows user control over the name that is written into the
ustar header
blocks for global extended header records. The name shall be the contents of
string, after the following character substitutions have been made:
| string |
|
| Includes: |
Replaced By: |
| %n |
An integer that represents the sequence number of the global extended
header record in the archive, starting at 1. |
| %p |
The process ID of the pax process. |
| %% |
A '%' character. |
Any other
'%' characters in
string produce undefined results.
If no
-o globexthdr.name= string is specified,
pax
shall use the following default value:
where $
TMPDIR represents the value of the
TMPDIR environment
variable. If
TMPDIR is not set,
pax shall use
/tmp.
- invalid=action
(Applicable only to the
-x pax format.) This keyword allows user
control over the action
pax takes upon encountering values in an
extended header record that, in
read or
copy mode, are invalid
in the destination hierarchy or, in
list mode, cannot be written in the
codeset and current locale of the implementation. The following are invalid
values that shall be recognized by
pax:
- *
- In read or copy mode, a filename or link name
that contains character encodings invalid in the destination hierarchy.
(For example, the name may contain embedded NULs.)
- *
- In read or copy mode, a filename or link name
that is longer than the maximum allowed in the destination hierarchy (for
either a pathname component or the entire pathname).
- *
- In list mode, any character string value (filename,
link name, user name, and so on) that cannot be written in the codeset and
current locale of the implementation.
The following mutually-exclusive values of the
action argument are
supported:
- bypass
In read or copy mode, pax
shall bypass the file, causing no change to the destination hierarchy. In
list mode, pax shall write all requested valid values for the
file, but its method for writing invalid values is unspecified.
- rename
In read or copy mode, pax
shall act as if the -i option were in effect for each file with invalid
filename or link name values, allowing the user to provide a replacement name
interactively. In list mode, pax shall behave identically to the
bypass action.
- UTF-8
When used in read, copy, or
list mode and a filename, link name, owner name, or any other field in
an extended header record cannot be translated from the pax UTF-8
codeset format to the codeset and current locale of the implementation,
pax shall use the actual UTF-8 encoding for the name.
- write
In read or copy mode, pax
shall write the file, translating or truncating the name, regardless of
whether this may overwrite an existing file with a valid name. In list
mode, pax shall behave identically to the bypass action.
If no
-o invalid= option is specified,
pax shall act as if
-o invalid= bypass were specified. Any overwriting of
existing files that may be allowed by the
-o invalid= actions
shall be subject to permission (
-p) and modification time (
-u)
restrictions, and shall be suppressed if the
-k option is also
specified.
- linkdata
(Applicable only to the
-x pax format.) In
write mode,
pax shall write the contents of a file to the archive even when that
file is merely a hard link to a file whose contents have already been written
to the archive.
- listopt=format
This keyword specifies the output format of the table of contents produced when
the
-v option is specified in
list mode. See List Mode Format
Specifications . To avoid ambiguity, the
listopt= format shall
be the only or final
keyword= value pair in a
-o
option-argument; all characters in the remainder of the option-argument shall
be considered part of the format string. When multiple
-o
listopt= format options are specified, the format strings shall
be considered a single, concatenated string, evaluated in command line
order.
- times
(Applicable only to the
-x pax format.) When used in
write
or
copy mode,
pax shall include
atime,
ctime, and
mtime extended header records for each file. See pax Extended Header
File Times .
In addition to these keywords, if the
-x pax format is specified,
any of the keywords and values defined in pax Extended Header , including
implementation extensions, can be used in
-o option-arguments, in
either of two modes:
- keyword=value
When used in
write or
copy mode, these keyword/value pairs shall
be included at the beginning of the archive as
typeflag g global
extended header records. When used in
read or
list mode, these
keyword/value pairs shall act as if they had been at the beginning of the
archive as
typeflag g global extended header records.
- keyword:=value
When used in
write or
copy mode, these keyword/value pairs shall
be included as records at the beginning of a
typeflag x extended
header for each file. (This shall be equivalent to the equal-sign form except
that it creates no
typeflag g global extended header records.)
When used in
read or
list mode, these keyword/value pairs shall
act as if they were included as records at the end of each extended header;
thus, they shall override any global or file-specific extended header record
keywords of the same names. For example, in the command:
pax -r -o "
gname:=mygroup,
" <archive
the group name will be forced to a new value for all files read from the
archive.
The precedence of
-o keywords over various fields in the archive is
described in pax Extended Header Keyword Precedence .
- -p string
- Specify one or more file characteristic options
(privileges). The string option-argument shall be a string
specifying file characteristics to be retained or discarded on extraction.
The string shall consist of the specification characters a ,
e , m , o , and p . Other
implementation-defined characters can be included. 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
(see the Base Definitions volume of IEEE Std 1003.1-2001,
Section 3.168, File Mode Bits), access time, modification time, and any other
implementation-defined file characteristics.
- m
Do not preserve file modification times.
- o
Preserve the user ID and group ID.
- p
Preserve the file mode bits. Other
implementation-defined file mode attributes may be preserved.
In the preceding list, "preserve" indicates that an attribute stored
in the archive shall be given to the extracted file, subject to the
permissions of the invoking process. The access and modification times of the
file shall be preserved unless otherwise specified with the
-p option
or not stored in the archive. All attributes that are not preserved shall be
determined as part of the normal file creation action (see
File
Read, Write, and Creation ).
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 shall
not set the S_ISUID and S_ISGID bits of the file mode.
If the preservation of any of these items fails for any reason,
pax shall
write a diagnostic message to standard error. Failure to preserve these items
shall affect the final exit status, but shall 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 shall take
precedence. For example, if
-p eme is specified, file
modification times are preserved.
- -s replstr
- Modify file or archive member names named by pattern
or file operands according to the substitution expression
replstr, using the syntax of the ed utility. The concepts of
"address" and "line" are meaningless in the context of
the pax utility, and shall not be supplied. The format shall be:
where as in
ed,
old is a basic regular expression and
new
can contain an ampersand,
'\n' (where
n is a digit)
backreferences, or subexpression matching. The
old string shall also be
permitted to contain <newline>s.
Any non-null character can be used as a delimiter (
'/' shown here).
Multiple
-s expressions can be specified; the expressions shall be
applied in the order specified, terminating with the first successful
substitution. The optional trailing
'g' is as defined in the
ed
utility. The optional trailing
'p' shall cause successful substitutions
to be written to standard error. File or archive member names that substitute
to the empty string shall be ignored when reading and writing archives.
- -t
- When reading files from the file system, and if the user
has the permissions required by utime() to do so, set the access
time of each file read to the access time that it had 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. In read mode, an archive member with the same name as a
file in the file system shall be extracted if the archive member is newer
than the file. In write mode, an archive file member with the same
name as a file in the file system shall be superseded if the file is newer
than the archive member. If -a is also specified, this is
accomplished by appending to the archive; otherwise, it is unspecified
whether this is accomplished by actual replacement in the archive or by
appending to the archive. In copy mode, the file in the destination
hierarchy shall 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 the STDOUT section). Otherwise, write archive member pathnames to
standard error (see the STDERR section).
- -x format
- Specify the output archive format. The pax utility
shall support the following formats:
- cpio
The cpio interchange format; see the
EXTENDED DESCRIPTION section. The default blocksize for this format for
character special archive files shall be 5120. Implementations shall support
all blocksize values less than or equal to 32256 that are multiples of
512.
- pax
The pax interchange format; see the
EXTENDED DESCRIPTION section. The default blocksize for this format for
character special archive files shall be 5120. Implementations shall support
all blocksize values less than or equal to 32256 that are multiples of
512.
- ustar
The tar interchange format; see the
EXTENDED DESCRIPTION section. The default blocksize for this format for
character special archive files shall be 10240. Implementations shall support
all blocksize values less than or equal to 32256 that are multiples of
512.
Implementation-defined formats shall specify a default block size as well as any
other block sizes supported for character special archive files.
Any attempt to append to an archive file in a format different from the existing
archive format shall cause
pax to exit immediately with a non-zero exit
status.
In
copy mode, if no
-x format is specified,
pax shall
behave as if
-x pax were specified.
- -X
- When traversing the file hierarchy specified by a pathname,
pax shall not descend into directories that have a different device
ID ( st_dev; see the System Interfaces volume of
IEEE Std 1003.1-2001, stat()).
The options that operate on the names of files or archive members (
-c,
-i,
-n,
-s,
-u, and
-v) shall interact as
follows. In
read mode, the archive members shall be selected based on
the user-specified
pattern operands as modified by the
-c,
-n, and
-u options. Then, any
-s and
-i options
shall modify, in that order, the names of the selected files. The
-v
option shall write names resulting from these modifications.
In
write mode, the files shall be selected based on the user-specified
pathnames as modified by the
-n and
-u options. Then, any
-s and
-i options shall modify, in that order, the names of
these selected files. The
-v option shall write names resulting from
these modifications.
If both the
-u and
-n options are specified,
pax shall not
consider a file selected unless it is newer than the file to which it is
compared.
In
list mode with the
-o listopt= format option, the
format argument shall be applied for each selected file. The
pax
utility shall append a <newline> to the
listopt output for each
selected file. The
format argument shall be used as the
format
string described in the Base Definitions volume of
IEEE Std 1003.1-2001, Chapter 5, File Format Notation, with the
exceptions 1. through 5. defined in the EXTENDED DESCRIPTION section of
printf, plus the following exceptions:
- 6.
- The sequence ( keyword) can occur before a format
conversion specifier. The conversion argument is defined by the value of
keyword. The implementation shall support the following
keywords:
- *
- Any of the Field Name entries in ustar Header Block and
Octet-Oriented cpio Archive Entry . The implementation may support the
cpio keywords without the leading c_ in addition to the form
required by Values for cpio c_mode Field .
- *
- Any keyword defined for the extended header in pax Extended
Header .
- *
- Any keyword provided as an implementation-defined extension
within the extended header defined in pax Extended Header .
For example, the sequence
"%(charset)s" is the string value of
the name of the character set in the extended header.
The result of the keyword conversion argument shall be the value from the
applicable header field or extended header, without any trailing NULs.
All keyword values used as conversion arguments shall be translated from the
UTF-8 encoding to the character set appropriate for the local file system,
user database, and so on, as applicable.
- 7.
- An additional conversion specifier character, T ,
shall be used to specify time formats. The T conversion specifier
character can be preceded by the sequence ( keyword=
subformat), where subformat is a date format as defined by
date operands. The default keyword shall be mtime and
the default subformat shall be:
- 8.
- An additional conversion specifier character, M ,
shall be used to specify the file mode string as defined in ls
Standard Output. If ( keyword) is omitted, the mode keyword
shall be used. For example, %.1M writes the single character
corresponding to the < entry type> field of the
ls -l command.
- 9.
- An additional conversion specifier character, D ,
shall be used to specify the device for block or special files, if
applicable, in an implementation-defined format. If not applicable, and (
keyword) is specified, then this conversion shall be equivalent to
%(keyword)u. If not applicable, and ( keyword)
is omitted, then this conversion shall be equivalent to
<space>.
- 10.
- An additional conversion specifier character, F ,
shall be used to specify a pathname. The F conversion character can
be preceded by a sequence of comma-separated keywords:
The values for all the keywords that are non-null shall be concatenated
together, each separated by a
'/' . The default shall be (
path)
if the keyword
path is defined; otherwise, the default shall be (
prefix,
name).
- 11.
- An additional conversion specifier character, L ,
shall be used to specify a symbolic line expansion. If the current file is
a symbolic link, then %L shall expand to:
"%s -> %s", <value of keyword>, <contents of link>
Otherwise, the
%L conversion specification shall be the equivalent of
%F .
The following operands shall be supported:
- directory
- The destination directory pathname for copy
mode.
- file
- A pathname of a file to be copied or archived.
- pattern
- A pattern matching one or more pathnames of archive
members. A pattern must be given in the name-generating notation of the
pattern matching notation in Pattern Matching Notation , including
the filename expansion rules in Patterns Used for Filename
Expansion . The default, if no pattern is specified, is to
select all members in the archive.
In
write mode, the standard input shall be used only if no
file
operands are specified. It shall be a text file containing a list of
pathnames, one per line, without leading or trailing <blank>s.
In
list and
read modes, if
-f is not specified, the
standard input shall be an archive file.
Otherwise, the standard input shall not be used.
The input file named by the
archive option-argument, or standard input
when the archive is read from there, shall be a file formatted according to
one of the specifications in the EXTENDED DESCRIPTION section or some other
implementation-defined format.
The file
/dev/tty shall be used to write prompts and read responses.
The following environment variables shall affect the execution of
pax:
- LANG
- Provide a default value for the internationalization
variables that are unset or null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, Internationalization
Variables for the precedence of internationalization variables used to
determine the values of locale categories.)
- LC_ALL
- If set to a non-empty string value, override the values of
all the other internationalization variables.
- LC_COLLATE
-
Determine the locale for the behavior 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.
- LC_CTYPE
- Determine the locale for the interpretation of sequences of
bytes of text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments and input files), the behavior of
character classes used in the extended regular expression defined for the
yesexpr locale keyword in the LC_MESSAGES category, and
pattern matching.
- LC_MESSAGES
- Determine the locale for the processing of affirmative
responses that should be used to affect the format and contents of
diagnostic messages written to standard error.
- LC_TIME
- Determine the format and contents of date and time strings
when the -v option is specified.
- NLSPATH
- Determine the location of message catalogs for the
processing of LC_MESSAGES .
- TMPDIR
- Determine the pathname that provides part of the default
global extended header record file, as described for the -o
globexthdr= keyword in the OPTIONS section.
- TZ
- Determine the timezone used to calculate date and time
strings when the -v option is specified. If TZ is unset or
null, an unspecified default timezone shall be used.
Default.
In
write mode, if
-f is not specified, the standard output shall
be the archive formatted according to one of the specifications in the
EXTENDED DESCRIPTION section, or some other implementation-defined format (see
-x format).
In
list mode, when the
-o listopt=
format has been
specified, the selected archive members shall be written to standard output
using the format described under List Mode Format Specifications . In
list mode without the
-o listopt=
format option,
the table of contents of the selected archive members shall be written to
standard output using the following format:
If the
-v option is specified in
list mode, the table of contents
of the selected archive members shall be written to standard output using the
following formats.
For pathnames representing hard links to previous members of the archive:
"%s == %s\n", <ls -l listing>, <linkname>
For all other pathnames:
where <
ls -l
listing> shall be the format
specified by the
ls utility with the
-l option. When writing
pathnames 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>-separated fields shall be
written.
In
list mode, standard output shall not be buffered more than a line at a
time.
If
-v is specified in
read,
write, or
copy modes,
pax shall write the pathnames it processes to the standard error output
using the following format:
These pathnames shall be written as soon as processing is begun on the file or
archive member, and shall be flushed to standard error. The trailing
<newline>, which shall not be buffered, is written when the file has
been read or written.
If the
-s option is specified, and the replacement string has a trailing
'p' , substitutions shall be written to standard error in the following
format:
"%s >> %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 pathnames or link names are written.
When
pax is in
read mode or
list mode, using the
-x
pax archive format, and a filename, link name, owner name, or any other
field in an extended header record cannot be translated from the
pax
UTF-8 codeset format to the codeset and current locale of the implementation,
pax shall write a diagnostic message to standard error, shall process
the file as described for the
-o invalid= option, and then shall
process the next file in the archive.
In
read mode, the extracted output files shall be of the archived file
type. In
copy mode, the copied output files shall be the type of the
file being copied. In either mode, existing files in the destination hierarchy
shall be overwritten only when all permission (
-p), modification time
(
-u), and invalid-value (
-o invalid=) tests allow it.
In
write mode, the output file named by the
-f option-argument
shall be a file formatted according to one of the specifications in the
EXTENDED DESCRIPTION section, or some other implementation-defined format.
A
pax archive tape or file produced in the
-x pax format
shall contain a series of blocks. The physical layout of the archive shall be
identical to the
ustar format described in ustar Interchange Format .
Each file archived shall be represented by the following sequence:
- *
- An optional header block with extended header records. This
header block is of the form described in pax Header Block , with a
typeflag value of x or g. The extended header
records, described in pax Extended Header , shall be included as the data
for this header block.
- *
- A header block that describes the file. Any fields in the
preceding optional extended header shall override the associated fields in
this header block for this file.
- *
- Zero or more blocks that contain the contents of the
file.
At the end of the archive file there shall be two 512-byte blocks filled with
binary zeros, interpreted as an end-of-archive indicator.
A schematic of an example archive with global extended header records and two
actual files is shown in pax Format Archive Example . In the example, the
second file in the archive has no extended header preceding it, presumably
because it has no need for extended attributes.
Figure: pax Format Archive Example
The
pax header block shall be identical to the
ustar header block
described in ustar Interchange Format , except that two additional
typeflag values are defined:
- x
- Represents extended header records for the following file
in the archive (which shall have its own ustar header block). The
format of these extended header records shall be as described in pax
Extended Header .
- g
- Represents global extended header records for the following
files in the archive. The format of these extended header records shall be
as described in pax Extended Header . Each value shall affect all
subsequent files that do not override that value in their own extended
header record and until another global extended header record is reached
that provides another value for the same field. The typeflag
g global headers should not be used with interchange media that
could suffer partial data loss in transporting the archive.
For both of these types, the
size field shall be the size of the extended
header records in octets. The other fields in the header block are not
meaningful to this version of the
pax utility. However, if this archive
is read by a
pax utility conforming to the ISO POSIX-2:1993
standard, the header block fields are used to create a regular file that
contains the extended header records as data. Therefore, header block field
values should be selected to provide reasonable file access to this regular
file.
A further difference from the
ustar header block is that data blocks for
files of
typeflag 1 (the digit one) (hard link) may be included, which
means that the size field may be greater than zero. Archives created by
pax -o linkdata shall include these data blocks with the
hard links.
A
pax extended header contains values that are inappropriate for the
ustar header block because of limitations in that format: fields
requiring a character encoding other than that described in the
ISO/IEC 646:1991 standard, fields representing file attributes not
described in the
ustar header, and fields whose format or length do not
fit the requirements of the
ustar header. The values in an extended
header add attributes to the following file (or files; see the description of
the
typeflag g header block) or override values in the following
header block(s), as indicated in the following list of keywords.
An extended header shall consist of one or more records, each constructed as
follows:
"%d %s=%s\n", <length>, <keyword>, <value>
The extended header records shall be encoded according to the
ISO/IEC 10646-1:2000 standard (UTF-8). The <
length>
field, <blank>, equals sign, and <newline> shown shall be limited
to the portable character set, as encoded in UTF-8. The <
keyword> and <
value> fields can be any UTF-8
characters. The <
length> field shall be the decimal length of
the extended header record in octets, including the trailing <newline>.
The <
keyword> field shall be one of the entries from the following
list or a keyword provided as an implementation extension. Keywords consisting
entirely of lowercase letters, digits, and periods are reserved for future
standardization. A keyword shall not include an equals sign. (In the following
list, the notations "file(s)" or "block(s)" is used to
acknowledge that a keyword affects the following single file after a
typeflag x extended header, but possibly multiple files after
typeflag g. Any requirements in the list for
pax to
include a record when in
write or
copy mode shall apply only
when such a record has not already been provided through the use of the
-o option. When used in
copy mode,
pax shall behave as if
an archive had been created with applicable extended header records and then
extracted.)
- atime
- The file access time for the following file(s), equivalent
to the value of the st_atime member of the stat structure
for a file, as described by the stat() function. The access time
shall be restored if the process has the appropriate privilege required to
do so. The format of the < value> shall be as described in
pax Extended Header File Times .
- charset
- The name of the character set used to encode the data in
the following file(s). The entries in the following table are defined to
refer to known standards; additional names may be agreed on between the
originator and recipient.
| <value> |
Formal Standard |
| ISO-IR 646 1990 |
ISO/IEC 646:1990 |
| ISO-IR 8859 1 1998 |
ISO/IEC 8859-1:1998 |
| ISO-IR 8859 2 1999 |
ISO/IEC 8859-2:1999 |
| ISO-IR 8859 3 1999 |
ISO/IEC 8859-3:1999 |
| ISO-IR 8859 4 1998 |
ISO/IEC 8859-4:1998 |
| ISO-IR 8859 5 1999 |
ISO/IEC 8859-5:1999 |
| ISO-IR 8859 6 1999 |
ISO/IEC 8859-6:1999 |
| ISO-IR 8859 7 1987 |
ISO/IEC 8859-7:1987 |
| ISO-IR 8859 8 1999 |
ISO/IEC 8859-8:1999 |
| ISO-IR 8859 9 1999 |
ISO/IEC 8859-9:1999 |
| ISO-IR 8859 10 1998 |
ISO/IEC 8859-10:1998 |
| ISO-IR 8859 13 1998 |
ISO/IEC 8859-13:1998 |
| ISO-IR 8859 14 1998 |
ISO/IEC 8859-14:1998 |
| ISO-IR 8859 15 1999 |
ISO/IEC 8859-15:1999 |
| ISO-IR 10646 2000 |
ISO/IEC 10646:2000 |
| ISO-IR 10646 2000 UTF-8 |
ISO/IEC 10646, UTF-8 encoding |
| BINARY |
None. |
The encoding is included in an extended header for information only; when
pax is used as described in IEEE Std 1003.1-2001, it
shall not translate the file data into any other encoding. The
BINARY
entry indicates unencoded binary data.
When used in
write or
copy mode, it is implementation-defined
whether
pax includes a
charset extended header record for a
file.
- comment
- A se
