pax(1)pax(1)NAMEpax - extracts, writes, and lists archive files; copies files and
directory hierarchies
SYNOPSIS
Listing Member Files of Archived Files
archive] options]... replstr]... [pattern]...
Extracting Archive Files
archive] options]... string]... replstr]... [pattern]...
Writing Archive Files
blocking] archive] options]... replstr]... format] [file]...
Copying Files
options]... string]... replstr]... [file]... directory
DESCRIPTION
The command extracts and writes member files of archive files; writes
lists of the member files of archives; and copies directory hierar‐
chies. The and flags specify the archive operation performed by the
command.
The pattern argument specifies a pattern that matches one or more paths
of archive members. A (backslash) character is not recognized in the
pattern argument and it prevents the subsequent character from having
any special meaning. If no pattern argument is specified, all members
are selected in the archive.
If a pattern argument is specified, but no archive members are found
that match the pattern specified, the command detects the error, exits
with a nonzero exit status, and writes a diagnostic message.
The command can read both and archives. In the case of this means that
can read ASCII archives (which are created with and binary archives
(which are created without the flag).
can also write archives that and can read; by default, writes archives
in the extended interchange format. also writes ASCII archives; use
the flag to specify this extended output format.
also reads and writes archives in the interchange format, IEEE Std
1003.1, 2003 Edition. Use the flag to specify this format. Refer to the
description of the option for more details.
The supported archive formats are automatically detected on input. All
three formats are explained in greater detail under
The four combinations of and are referred to as the four modes of oper‐
ation: and modes, corresponding respectively to the four forms shown in
the section.
In mode (when neither nor are specified), 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 hierar‐
chy rooted at that file shall be listed as well.
In mode (when is specified, but is not), shall extract 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 shall
be extracted as well. The extracted files shall be created
performing pathname resolution with the directory in which 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.
In mode (when is specified, but is not), shall write the contents
of the file operands to the standard output in an archive for‐
mat. 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.
In mode (when both and are specified), shall copy the file oper‐
ands 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 subdirec‐
tory of one of the files to be copied, the results are unspeci‐
fied. 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 or modes, if intermediate directories are necessary to extract an
archive member, shall perform actions equivalent to the function
defined in the System Interfaces volume of IEEE Std 1003.1-2001, called
with the following arguments:
1. The intermediate directory used as the path argument,
2. The value of the bitwise-inclusive OR of and as the mode argument.
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, except that if the files to be linked are sym‐
bolic links then separate copies of the symbolic link shall be created
instead. 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 session, a diagnostic message shall be displayed
with the name of a file that can be used to extract the data.
Options
Appends files to the end of the archive.
Certain devices might not support appending.
Backs up and extracts optional entries of access control lists for
files.
This option is applicable only for the format. The
default behaviour is not to back up or extract the
optional ACL entries. The PAX-ENH product must be
installed to enable this option. If a login name cannot
be found in the password file of the extracting machine,
the file is extracted without its ACL and a warning mes‐
sage is printed. Hence, it might be required to extract
the password file before attempting to extract ACLs.
Specifies the block size for output to be the positive decimal integer
of bytes
specified by the blocking argument. Blocking is automat‐
ically determined on input.
To create portable archives, specify a block size value
less than or equal to 32,256 in multiples of 512.
Default blocking when creating archives depends on the
archive format. (See the flag description.)
Matches all file or archive members except those specified
by the pattern or file arguments.
Causes directories being copied or archived, or archived
directories being extracted, to match only the directory
or archived directory itself and not the contents of the
directory or archived directory.
Specifies the path of an archive file to be used instead of standard
input (when the
flag is not specified) or the standard output (when the
flag is specified but the flag is not). When specified
with the flag, any files written to the archive are
appended to the end of the archive.
If a symbolic link referencing a file of type directory is specified
on the command line, 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. Oth‐
erwise, if a symbolic link referencing a file of any
other file type which can normally archive is specified
on the command line, then shall archive the file refer‐
enced by the link, using the name of the link. The
default behavior shall be to archive the symbolic link
itself.
Renames files or archives interactively. For each
archive member that matches the pattern argument or file
that matches a file argument, a prompt is written to the
terminal that contains the name of a file or archive
member. A line is then read from the terminal. If this
line is empty, the file or archive member is skipped. If
this line consists of a dot, the file or archive member
is processed with no modification to its name. Other‐
wise, its name is replaced with the contents of the
line. The command immediately exits with a nonzero exit
status if an End-of-File is encountered when reading a
response or if it cannot read or write to the terminal.
Prevents the command from writing over existing files.
Links files when copying files.
When both and are specified, hard links are established
between the source and destination file hierarchies
whenever possible.
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, 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. Oth‐
erwise, if a symbolic link referencing a file of any
other file type which can normally archive is specified
on the command line or encountered during the traversal
of a file hierarchy, 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.
Selects the first archive member that matches each
pattern argument. No more than one archive member is
matched for each pattern (although members of type
directory will still match the file hierarchy rooted at
that file).
Provides 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:
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
causes to print an error message and ignore the keyword.
However will continue processing the archive. Keywords
in the options argument shall be a string that would be
a valid portable filename as described in the Base Defi‐
nitions 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 porta‐
ble filenames.
The value field shall consist of zero or more charac‐
ters; 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 options can be specified; if keywords
given to these multiple options conflict, the keywords
and values appearing later in command line sequence
shall take precedence and the earlier shall be silently
ignored. Also, if the value specified for a keyword is
invalid, shall print a suitable error message and behave
as if the keyword were not specified in the command
line. The following keyword values of options shall be
supported for the file formats as indicated:
(Applicable only to the
format.) When used in or mode, shall omit from
extended header records that it produces any key‐
words matching the string pattern. When used in
or mode, 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 and For
example, the following pattern:
would suppress user and group name keywords in
the extended header.
See for extended header record keyword usage.
When multiple options are specified, the patterns
shall be additive; all keywords matching the
specified string patterns shall be omitted from
extended header records that pax produces.
(Applicable only to the
format.) path specifies a file or a directory to
be excluded from the tree being backed up or
extracted. The path specified must be a part of
the tree. Otherwise, the specified path will be
ignored. The PAX-ENH product must be installed
to enable this option.
(Applicable only to the
format.) This keyword allows user control over
the name that is written into the header blocks
for the extended header produced under the cir‐
cumstances described in The name shall be the
contents of string, after the following character
substitutions have been made:
The directory name of the file, equivalent to the
result of the dirname utility on the
translated pathname.
The filename of the file, equivalent to the result
of the basename utility on the
translated pathname.
The process ID of the pax process.
A '%' character.
If there are any other '%' characters in or if no
is specified, shall use the following default
value:
(Applicable only to the
format.) This keyword allows user control over
the name that is written into the header blocks
for global extended header records. The name
shall be the contents of string, after the fol‐
lowing character substitutions have been made:
An integer that represents the sequence number of
the global extended header record
in the archive, starting at 1.
The process ID of the pax process.
A '%' character.
If there are any other '%' characters in or if no
is specified, shall use the following default
value:
where represents the value of the environment
variable. If is not set, shall use
(Applicable only to the
format.) graph_file defines the graph file. The
graph file is a text file containing the list of
file names of trees to be included or excluded
from the backup graph. Graph file entries con‐
sist of a line beginning with either (include) or
(exclude), followed by white space, and then the
path name of a tree. Lines not beginning with or
are treated as an error. There is no default
graph file. For example, to back up all of
except for the subtree a file could be created
with the following two records:
The PAX-ENH product must be installed to enable
this option.
(Applicable only to the
format.) This keyword allows user control over
the action takes upon encountering values in an
extended header record that, in or mode, are
invalid in the destination hierarchy. The follow‐
ing are invalid values that shall be recognized
by In or mode, a filename or link name that is
longer than the maximum allowed in the destina‐
tion hierarchy.
The following mutually-exclusive values of the
action argument are supported:
In or mode, shall bypass the file, causing
no change to the destination hierarchy.
In or mode, shall act as if the option were
in effect for each file with invalid
filename or link name values, allowing
the user to provide a replacement name
interactively.
In or mode, shall write the file, translat‐
ing the name regardless of whether this
may overwrite an existing file with a
valid name. This action argument is not
supported for files having invalid link
names.
If no option is specified, shall act as if was
specified. Any overwriting of existing files that
may be allowed by the actions shall be subject to
permission and modification time restrictions,
and shall be suppressed if the option is also
specified.
(Applicable only to the
format.) In mode, 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.
This keyword specifies the output format of the table of
contents produced when the
option is specified in mode. See To avoid ambigu‐
ity, the format shall be the only or final value
pair in a option-argument; all characters in the
remainder of the option-argument shall be consid‐
ered part of the format string. When multiple
options are specified, the format strings shall
be considered a single, concatenated string,
evaluated in command line order.
(Applicable only to the
format.) When used in or mode, shall include and
extended header records for each file. See
In addition to these keywords, if the format is speci‐
fied, any of the keywords and values defined in can be
used in option-arguments, in either of two modes:
When used in
or mode, these keyword/value pairs shall be
included at the beginning of the archive as
global extended header records. When used in or
mode, these keyword/value pairs shall act as if
they had been at the beginning of the archive as
global extended header records.
When used in
or mode, these keyword/value pairs shall be
included as records at the beginning of a
extended header for each file. (This shall be
equivalent to the equal-sign form except that it
creates no global extended header records.) When
used in or 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 below, the group name
will be forced to a new value for all files read
from the archive:
The precedence of keywords over various fields in the
archive is described in
Specifies one or more file characteristics
to be retained or discarded on extraction. The string
argument consists of the characters and Multiple charac‐
teristics can be concatenated within the same string and
multiple flags can be specified. The specification flags
have the following meanings:
Does not retain file-access times.
Retains the user ID, group ID, access permission, access
time, and modification time.
Does not retain file-modification times.
Retains the user ID and the group ID.
Retains the access permission.
Note that "retain" means that an attribute stored in the
archive is given to the extracted file, subject to the
permissions of the invoking process; otherwise, the
attribute is determined as part of the normal file cre‐
ation action.
If neither the nor the flag is specified, or the user ID
and group ID are not retained, the command does not set
the and bits of the access permission. If the retention
of any of these items fails, the command writes a diag‐
nostic message to standard error. Failure to retain any
of the items affects the exit status, but does not cause
the extracted file to be deleted. If specification flags
are duplicated or conflict with each other, the ones
given last shall take precedence. For example, if is
specified, file-modification times are retained.
Reads an archive file from the standard input.
Modifies file-member or
archive-member names specified by the pattern or file
arguments according to the substitution expression
replstr, using the syntax of the command. The substitu‐
tion expression has the following format:
whereas in the command, old is a basic regular expres‐
sion and new can contain an (ampersand), (n is a digit)
back references, or subexpression matching. The old
string can also contain newline characters.
Any non-null character can be used as a delimiter (the
(slash) character is the delimiter in the previous for‐
mat). Multiple flag expressions can be specified; the
expressions are applied in the order specified, termi‐
nating with the first successful substitution. The
optional trailing character performs as in the command.
The optional trailing character causes successful sub‐
stitutions to be written to the standard error. File-
member or archive-member names that substitute to the
empty string are ignored when reading and writing ar‐
chives.
Causes the access times of the archived files to be
the same as they were before being read by the command.
Ignores files that are older (having a less recent file modification
time) than a preexisting file or archive member with the
same name.
When extracting files (flag), an archive member with the
same name as a file in the file system is extracted if
the archive member is newer than the file.
When writing files to an archive file (flag), an archive
member with the same name as a file in the file system
is superseded if the file is newer than the archive mem‐
ber.
When copying files to a destination directory (flags),
the file in the destination hierarchy is 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.
Writes information about the process. If neither the
or flags are specified, the flag produces a verbose ta‐
ble of contents that resembles the output of otherwise,
archive-member pathnames are written to standard error.
Writes files to the standard output in the specified archive format.
Specifies the output archive format. The
command recognizes the following formats:
Extended
interchange format. The default blocking value
for this format for character special archive
files is 5120. Blocking values from 512 to
32,256 in increments of 512 are supported.
The interchange format. See IEEE Std 1003.1, 2003
Edition. The default block size for this format
for character special archive files shall be
5120. Blocking values from 512 to 32,256 in
increments of 512 are supported.
This is an extended format. The format should be
used for archiving and extracting files having
one or more of the following properties: size
8GB or more, UID or GID greater than 2097151,
user or group names longer than 31 characters,
pathname longer than 256 characters or link name
longer than 100 characters. Archives of this
format are reported as "USTAR format archive
extended" in the and mode when the (verbose)
flag is specified in the command line.
Extended
interchange format. This is the default output
archive format. The default blocking value for
this format for character special archive files
is 10240. Blocking values from 512 to 32,256 in
increments of 512 are supported.
Any attempt to append to an archive file in a format
different from the existing archive format causes the
command to exit immediately with a nonzero exit status.
When traversing the file hierarchy specified by a pathname, the
command does not descend into directories that have a
different device ID.
Prompts interactively for the disposition of each
file. Substitutions specified by flags are performed
before you are prompted for disposition. An EOF marker
or an input line starting with the character causes to
exit. Otherwise, an input line starting with anything
other than causes the file to be ignored. This flag
cannot be used in conjunction with the flag.
Option Interaction and Processing Order
Specifying more than one of the mutually-exclusive options and shall
not be considered an error and the last option specified shall deter‐
mine the behavior of the utility.
The flags that operate on the names of files or archive members and
interact as follows.
When extracting files flag), archive members are selected, using the
modified names, according to the user-specified pattern arguments as
modified by the and flags. Then, any and flags modify, in that order,
the names of the selected files. The flag writes the names resulting
from these modifications.
When writing files to an archive file flag), or when copying files, the
files are selected according to the user-specified pathnames as modi‐
fied by the and flags. Then, any and flags modify, in that order, the
names resulting from these modifications. The flag writes the names
resulting from these modifications.
If both the and flags are specified, the command does not consider a
file selected unless it is newer than the file to which it is compared.
Listing Member Files of Archived Files
You can specify the command without the or flags with the or and flags,
and with the pattern argument.
If neither the or flags are included, lists the contents of the speci‐
fied archive, one file per line.
If the flag is specified, the listing is output in the command format.
In the verbose listing lists hard link pathnames as follows:
lists symbolic link pathnames as follows:
In the case of hard links, pathname is the name of the file that is
being extracted, and linkname is the name of a file that appeared ear‐
lier in the archive.
Extracting Archive Files
The flag can be specified with the or and flags, and a pattern argu‐
ment.
Writing Archive Files
The flag can be specified with the or and flags and with file argu‐
ments.
If is specified, but no files are specified, standard input is used.
If neither or are specified, standard input must be an archive file.
Copying Files
The and flags can be specified with the or and flags and with the file
arguments. A directory argument must be specified.
List Mode Format Specifications
In mode with the format option, the format argument shall be applied
for each selected file. The utility shall append a newline to the out‐
put 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 section of plus the following exceptions:
1. through 5. Defined in the section of
6. The sequence can occur before a format conversion specifier. The
conversion argument is defined by the value of keyword. The imple‐
mentation shall support the following keywords:
· Any of the Field Name entries in Header Block and Octet-Oriented
Archive Entry.
· Any keyword defined for the extended header in
For example, the sequence "%(charset)s" is the string value of
the name of the character set in the extended header. Refer to
the section for the list of keywords in each format.
The result of the keyword conversion argument shall be the value
from the applicable header field or extended header, without any
trailing NULL characters.
7. An additional conversion specifier character, shall be used to
specify time formats. The conversion specifier character can be
preceded by the sequence where subformat is a date format as
defined by date operands. The default keyword shall be and the
default subformat shall be:
8. An additional conversion specifier character, shall be used to
specify the file mode string as defined in Standard Output. If is
omitted, the mode keyword shall be used. For example, writes the
single character corresponding to the entry_type field of the com‐
mand
9. An additional conversion specifier character, shall be used to
specify the device for block or special files, if applicable. If
not applicable, and is specified, then this conversion shall be
equivalent to If not applicable, and is omitted, then this conver‐
sion shall be equivalent to space.
10. An additional conversion specifier character, shall be used to
specify a pathname. The conversion character can be preceded by a
sequence of comma-separated keywords:
The values for all the keywords that are non-null shall be concate‐
nated together, each separated by a '/'. The default shall be if
the keyword path is defined; otherwise, the default shall be
11. An additional conversion specifier character, shall be used to
specify a symbolic line expansion. If the current file is a sym‐
bolic link, then %L shall expand to:
Otherwise, the conversion specification shall be the equivalent of
EXTENDED DESCRIPTION
cpio Interchange Format
The octet-oriented archive format shall be a series of entries, each
comprising a header that describes the file, the name of the file, and
then the contents of the file. The fields of the header are described
below:
Identify the archive as being a transportable archive by containing the
identifying value "070707".
Contains values that uniquely identify the file within the archive. No
files contain the same pair of and values unless they are
links to the same file.
Contains the file type and access permissions.
Contains the user ID of the owner of the file.
Contains the group ID of the group owner of the file.
Contains the number links of the file.
Contains information for character or block special files.
Contains the latest time of modification of the file at the time the
archive
was created.
Contains the length of the pathname, including the terminating NULL
character.
Contains the length of the file in bytes. This shall be the length of
the
data section following the header structure.
ustar Interchange Format
A archive tape or file shall contain a series of logical records. Each
logical record shall be a fixed-size logical record of 512 bytes. Each
file archived shall be represented by a header logical record that
describes the file, followed by zero or more logical records that give
the contents of the file. At the end of the archive file there shall be
two 512-octet logical records filled with binary zeros, interpreted as
an end-of-archive indicator. The header logical record shall contain
the following fields:
The name and the prefix fields shall produce the pathname of the file.
A new
pathname shall be formed, if prefix is not an empty string
(its first character is not NULL), by concatenating prefix
(up to the first NULL character), a slash character, and
name; otherwise, name is used alone. In this manner, path‐
names up to 256 characters can be supported. If a pathname
does not fit in the space provided, shall notify the user
of the error, and shall not store any part of the file-
header or data on the medium.
The mode field provides 12 bits encoded in the ISO/IEC 646:1991 stan‐
dard octal
digit representation to encode the permissions.
The user and group ID of the owner and group of the
file, respectively. If or is greater than 2097151, a value
of -1 will be stored in the respective field of the header.
If the corresponding name (user name for uid and group name
for gid) also could not be stored in the archive, shall
notify the user of the error but shall include the other
attributes of the file and its data on the medium.
The names of the owner and group of the file, respectively. If the user
or group
name is longer than 31 characters, it will not be stored in
the respective field of the header. shall notify the user
of the error but shall include the other attributes of the
file and its data on the medium.
The size of the file in bytes. If the size of the files is greater than
or equal to
8GB, shall notify the user of the error, and shall not
store any part of the file-header or data on the medium.
The modification time of the file at the time it was archived.
Specifies the type of file archived. All of the
fields shall be coded in the ISO/IEC 646:1991 standard IRV
Represents a regular file.
Represents a file linked to another file, of any type, pre‐
viously archived. The
linked-to name is specified in the field with a
NULL-character terminator if it is less than 100
bytes in length.
Represents a symbolic link. The contents of the symbolic
link shall be stored
in the field.
Represents character special files and block special files
respectively.
Specifies a directory or subdirectory.
Specifies a FIFO special file. Note that the archiving of a
FIFO file archives
the existence of this file and not its contents.
The is the pathname of the target of a symbolic or hard link.
It is limited to 100 characters. If the name does not fit
in the space provided, shall notify the user of the error,
and shall not attempt to store the link on the medium.
When the field contains '3' or '4' the and fields shall contain the
major and minor numbers of the device respectively.
The octal value of the simple sum of all bytes in the header logical
record.
Each bytes in the header shall be treated as an unsigned
value. When calculating the checksum, the field is treated
as if it were all spaces.
The magic field is the specification that this archive was output in
this archive
format. If this field contains (the five characters from
the ISO/IEC 646:1991 standard IRV shown followed by NULL),
the uname and gname fields shall contain the ISO/IEC
646:1991 standard IRV representation of the owner and group
of the file, respectively. When the file is restored by a
privileged, protection-preserving version of the utility,
the user and group databases shall be scanned for these
names. If found, the user and group IDs contained within
these files shall be used rather than the values contained
within the uid and gid fields.
The version field is two bytes containing the characters "00" (zero-
zero).
pax Interchange Format
A archive tape or file produced in the format shall contain a series of
blocks. The physical layout of the archive shall be identical to the
ustar format described in Each file archived shall be represented by
the following sequence:
1. An optional header block with extended header records. This header
is of the form described in with a value of or The extended header
records, described in shall be included as the data for this header
block.
2. 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.
3. 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.
pax Header Block
The header block shall be identical to the header block described in
except that two additional typeflag values are defined:
Represents extended header records for the following file in the ar‐
chive (which
shall have its own header block). The format of these
extended header records shall be as described in the sec‐
tion of this manpage.
Represents global extended header records for the following files in
the archive.
The format of these extended header records shall be as
described in 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 global headers should not be used with inter‐
change media that could suffer partial data loss in trans‐
porting the archive.
For both of these types, the size field shall be the size of the
extended header records in bytes. The other fields in the header block
are not meaningful to this version of the pax utility.
A further difference from the 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 shall include these data blocks with the hard links.
pax Extended Header
A extended header contains values that are inappropriate for the header
block because of limitations in that format: fields representing file
attributes not described in the header, and fields whose format or
length do not fit the requirements of the header. The values in an
extended header add attributes to the following file (or files; see the
description of the 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 con‐
structed as follows:
The keyword field shall be one of the entries from the following list.
A keyword shall not include an equals sign. In the following list, the
notations "file(s)" or "block(s)" are used to acknowledge that a key‐
word affects the following single file after a extended header, but
possibly multiple files after Any requirements in the list for to
include a record when in or mode shall apply only when such a record
has not already been provided through the use of the option. When used
in mode, shall behave as if an archive had been created with applicable
extended header records and then extracted.
The file access time for the following file(s), equivalent to the value
of the
member of the structure for a file, as described by the
function. The format of the value shall be as described in
A series of characters used as a comment. All characters in the
value field shall be ignored by
The group ID of the group that owns the file, expressed as a decimal
number
using digits from the ISO/IEC 646:1991 standard. This
record shall override the field in the following header
block(s). When used in or mode, shall include a extended
header record for each file whose group ID is greater than
2097151 (octal 7777777).
The group of the file(s), formatted as a group name in the group data‐
base.
This record shall override the and fields in the following
header block(s), and any extended header record. When used
in or mode, shall include a extended header record for each
file whose group name cannot be represented in the header.
The pathname of a link being created to another file, of any type, pre‐
viously
archived. This record shall override the field in the fol‐
lowing header block(s). The following header block shall
determine the type of link created. If typeflag of the fol‐
lowing header block is 1, it shall be a hard link. If type‐
flag is 2, it shall be a symbolic link and the value shall
be the contents of the symbolic link. When used in or mode,
shall include a extended header record for each link whose
pathname cannot be represented in the header.
The file modification time of the following file(s), equivalent to the
value of
the member of the structure for a file, as described in the
function. This record shall override the field in the fol‐
lowing header block(s). The modification time shall be
restored if the process has the appropriate privilege
required to do so. The format of the value is described in
The pathname of the following file(s). This record shall override the
and fields in the following header block(s). When used in
or mode, pax shall include a extended header record for
each file whose pathname cannot be represented entirely in
the header.
The size of the file in bytes, expressed as a decimal number using dig‐
its
from the ISO/IEC 646:1991 standard. This record shall over‐
ride the field in the following header block(s). When used
in or mode, shall include a extended header record for each
file with a size value greater than 8589934591 (octal
77777777777).
The user ID of the file owner, expressed as a decimal number using dig‐
its
from the ISO/IEC 646:1991 standard. This record shall over‐
ride the field in the following header block(s). When used
in or mode, shall include a extended header record for each
file whose owner ID is greater than 2097151 (octal
7777777).
The owner of the following file(s), formatted as a user name in the
user
database. This record shall override the and fields in the
following header block(s), and any extended header record.
When used in or mode, shall include a extended header
record for each file whose user name cannot be represented
entirely in the header.
Indicates that the optional ACL entry for the file has been backed up
for HFS
files and its value will be equal to 1. This record is
written to the extended header if option is specified while
creating the archive, the HFS file has optional ACL entries
and the ACL entries are good.
Indicates that the optional ACL entry for the file has been backed up
for JFS
files and its value will be equal to 1. This record is
written to the extended header if option is specified while
creating the archive, the JFS file has optional ACL entries
and the ACL entries are good.
The number of ACL entries that have been written to the extended
header.
This is common to both HFS and JFS. This record is written
to the extended header if option is specified while creat‐
ing the archive, the JFS file has optional ACL entries and
the ACL entries are good.
The ACL entries for the file.
This record is written to the extended header if option is
specified while creating the archive, the file has optional
ACL entries and the ACL entries are good. The format for
HFS ACL entries will be:
The format for JFS ACL entries will be:
However, the corresponding username/groupname of the
uid/gid are written to the header.
If the value field is zero length, it shall delete any header block
field, previously entered extended header value, or global extended
header value of the same name.
If a keyword in an extended header record (or in a option-argument)
overrides or deletes a corresponding field in the header block, shall
ignore the contents of that header block field.
Unlike the header block fields, NULLs shall not delimit values; all
characters within the value field shall be considered data for the
field. None of the length limitations of the header block fields in
shall apply to the extended header records.
pax Extended Header Keyword Precedence
This section describes the precedence in which the various header
records and fields and command line options are selected to apply to a
file in the archive. When is used in or modes, it shall determine a
file attribute in the following sequence:
1. If keyword-prefix is used, the affected attributes shall be deter‐
mined from Step 7., if applicable, or ignored otherwise.
2. If is used, the affected attributes shall be ignored.
3. If is used, the affected attribute shall be assigned the value.
4. If there is a extended header record, the affected attribute shall
be assigned the value. When extended header records conflict, the
last one given in the header shall take precedence.
5. If is used, the affected attribute shall be assigned the value.
6. If there is a global extended header record, the affected attribute
shall be assigned the value. When global extended header records
conflict, the last one given in the global header shall take prece‐
dence.
7. Otherwise, the attribute shall be determined from the header block.
pax Extended Header File Times
The utility shall write an record for each file in or modes if the
file's modification time cannot be represented exactly in the header
logical record described in This can occur if the time is out of range,
or if the file system of the underlying implementation supports non-
integer time granularities and the time is not an integer. All of these
time records shall be formatted as a decimal representation of the time
in seconds since the Epoch. If a period decimal point character is
present, the digits to the right of the point shall represent the units
of a sub second timing granularity, where the first digit is tenths of
a second and each subsequent digit is a tenth of the previous digit.
RETURN VALUE
The command returns a value of 0 (zero) if all files were successfully
processed; otherwise, returns a value greater than 0 (zero).
EXAMPLES
To copy the contents of the current directory to the tape drive, enter:
To copy the directory hierarchy to enter:
To read the archive with all files rooted in the directory in the ar‐
chive extracted relative to the current directory, enter:
All of the preceding examples create archives in format.
The following pairs of commands demonstrate conversions from and to In
all cases, the examples show comparable command-line usage rather than
identical output formats. The flag can be specified to the commands
shown here, producing archives to select specific output formats:
Note: When you use the flag (interactively renames files) on files to
which there are hard links, does create hard links to the renamed
files.
WARNINGS
Because of industry standards and interoperability goals, does not sup‐
port the archival of files of size 8GB or larger for both and formats.
Also, does not support user and group IDs greater than or equal to
2048K for format. does not support user and group IDs greater than or
equal to 256K for format. With format, files with user IDs greater
than or equal to 2048K are restored under the user ID of the current
process, unless the user name exists. The same applies for group IDs.
In format, files with user or group IDs greater than or equal to 256K
will not be recovered with the original user or group IDs, respec‐
tively.
will automatically determine a block size only up to 32,768 on input.
By default, archives created with more than 32,768 block size will be
read in terms of 32,768 block size.
removes the and characters from the archive-member names wherever they
are not needed to address the file. For instance, will be stored as
but will be stored as
AUTHOR
was developed by Mark H. Colburn, OSF, and HP.
SEE ALSOed(1), tar(4), disk(7), mt(7).
STANDARDS CONFORMANCEpax(1)
