pax(1p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

PAX(1P)                 POSIX Programmer's Manual                PAX(1P)

PROLOG         top

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME         top

       pax — portable archive interchange

SYNOPSIS         top

       pax [-dv] [-c|-n] [-H|-L] [-o options] [-f archive] [-s replstr]...
           [pattern...]

       pax -r[-c|-n] [-dikuv] [-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] [-o options]... [-p string]...
           [-s replstr]... [file...] directory

DESCRIPTION         top

       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 and
                 each entry in this list shall be processed as if it had
                 been a file operand on the command line. 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 a pax format archive file and then
                 subsequently extracted, except that copying of sockets
                 may be supported even if archiving them in write mode
                 is not supported, and 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 POSIX.1‐2017, 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 POSIX.1‐2017, 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.

OPTIONS         top

       The pax utility shall conform to the Base Definitions volume of
       POSIX.1‐2017, 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 POSIX.1‐2017 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, when
                 neither -H or -L are specified, 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, when
                 neither -H or -L are specified, 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 POSIX.1‐2017, Section 3.282,
                 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 Section 2.13.1, Patterns
                       Matching a Single Character and Section 2.13.2,
                       Patterns Matching Multiple Characters.  For
                       example:

                           -o delete=security.*

                       would suppress security-related information. See
                       pax Extended Header for extended header record
                       keyword usage.

                       When multiple -odelete=pattern 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.

                 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:

                           %d/PaxHeaders.%p/%f

                 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:

                           $TMPDIR/GlobalHead.%p.%n

                       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:

                       binary    In write mode, pax shall generate a
                                 hdrcharset=BINARY extended header
                                 record for each file with a filename,
                                 link name, group name, owner name, or
                                 any other field in an extended header
                                 record that cannot be translated to the
                                 UTF‐8 codeset, allowing the archive to
                                 contain the files with unencoded
                                 extended header record values. In read
                                 or copy mode, pax shall use the values
                                 specified in the header without
                                 translation, regardless of whether this
                                 may overwrite an existing file with a
                                 valid name. In list mode, pax shall
                                 behave identically to the bypass
                                 action.

                       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. If
                                 a hdrcharset extended header record is
                                 in effect for this file, the character
                                 set specified by that record shall be
                                 used instead of UTF‐8. If a
                                 hdrcharset=BINARY extended header
                                 record is in effect for this file, no
                                 translation shall be performed.

                       write     In read or copy mode, pax shall write
                                 the file, translating 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 -oinvalid=bypass were specified. Any
                       overwriting of existing files that may be allowed
                       by the -oinvalid= 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 -olistopt=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
                       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
                       <equals-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.  If the -o delete=pattern, -o
                 keyword=value, or -o keyword:=value options are used to
                 override or remove any extended header data needed to
                 find files in an archive (e.g., -o delete=size for a
                 file whose size cannot be represented in a ustar header
                 or -o size=100 for a file whose size is not 100 bytes),
                 the behavior is undefined.

       -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 POSIX.1‐2017,
                       Section 3.169, 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 Section
                 1.1.1.4, 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:

                     -s /old/new/[gp]

                 where as in ed, old is a basic regular expression and
                 new can contain an <ampersand>, '\n' (where n is a
                 digit) back-references, or subexpression matching. The
                 old string shall also be 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 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.

       -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 POSIX.1‐2017, stat()).

       Specifying more than one of the mutually-exclusive options -H and
       -L shall not be considered an error and the last option specified
       shall determine the behavior of the utility.

       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.

   List Mode Format Specifications
       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 POSIX.1‐2017, Chapter
       5, File Format Notation, with the exceptions 1. through 6.
       defined in the EXTENDED DESCRIPTION section of printf, plus the
       following exceptions:

       7.    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 Table 4-14, ustar
                 Header Block and Table 4-16, Octet-Oriented cpio
                 Archive Entry.  The implementation may support the cpio
                 keywords without the leading c_ in addition to the form
                 required by Table 4-16, Octet-Oriented cpio Archive
                 Entry.

             --  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 (or alternative encoding
             specified by any hdrcharset extended header record) to the
             character set appropriate for the local file system, user
             database, and so on, as applicable.

       8.    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:

                 %b %e %H:%M %Y

       9.    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.

       10.   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>.

       11.   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:

                 (keyword[,keyword] ... )

             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).

       12.   An additional conversion specifier character, L, shall be
             used to specify a symbolic link 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.

OPERANDS         top

       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 Section
                 2.13, Pattern Matching Notation, including the filename
                 expansion rules in Section 2.13.3, Patterns Used for
                 Filename Expansion.  The default, if no pattern is
                 specified, is to select all members in the archive.

STDIN         top

       In write mode, the standard input shall be used only if no file
       operands are specified. It shall be a file containing a list of
       pathnames, each terminated by a <newline> character.

       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.

INPUT FILES         top

       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.

ENVIRONMENT VARIABLES         top

       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 POSIX.1‐2017, Section 8.2,
                 Internationalization Variables 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 used to process affirmative
                 responses, and the locale used to affect the format and
                 contents of diagnostic messages and prompts 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.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       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 -olistopt=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 -olistopt=format option, the table of
       contents of the selected archive members shall 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 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:

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

       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
       pathname (plus any associated information and a <newline>
       terminator) at a time.

STDERR         top

       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:

           "%s\n", <pathname>

       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 using the -xpax archive format, if a filename, link name,
       group name, owner name, or any other field in an extended header
       record cannot be translated between the codeset in use for that
       extended header record and the character set of the current
       locale, pax shall write a diagnostic message to standard error,
       shall process the file as described for the -o invalid= option,
       and then shall continue processing with the next file.

OUTPUT FILES         top

       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
       (-oinvalid=) 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.

EXTENDED DESCRIPTION         top

   pax Interchange Format
       A pax archive tape or file produced in the -xpax 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 Figure 4-1, 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 4-1: pax Format Archive Example

   pax Header Block
       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.

   pax Extended Header
       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 encoding. The <length> field,
       <blank>, <equals-sign>, and <newline> shown shall be limited to
       the portable character set, as encoded in UTF‐8. The <keyword>
       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>.  If there is a hdrcharset
       extended header in effect for a file, the value field for any
       gname, linkpath, path, and uname extended header records shall be
       encoded using the character set specified by the hdrcharset
       extended header record; otherwise, the value field shall be
       encoded using UTF‐8. The value field for all other keywords
       specified by POSIX.1‐2008 shall be encoded using UTF‐8.

       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 appropriate privileges 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
                 POSIX.1‐2008, 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 series of characters used as a comment. All
                 characters in the <value> field shall be ignored by
                 pax.

       gid       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 gid field in the following header block(s). When
                 used in write or copy mode, pax shall include a gid
                 extended header record for each file whose group ID is
                 greater than 2097151 (octal 7777777).

       gname     The group of the file(s), formatted as a group name in
                 the group database. This record shall override the gid
                 and gname fields in the following header block(s), and
                 any gid extended header record. When used in read,
                 copy, or list mode, pax shall translate the name from
                 the encoding in the header record to the character set
                 appropriate for the group database on the receiving
                 system. If any of the characters cannot be translated,
                 and if neither the -oinvalid=UTF‐8 option nor the
                 -oinvalid=binary option is specified, the results are
                 implementation-defined.  When used in write or copy
                 mode, pax shall include a gname extended header record
                 for each file whose group name cannot be represented
                 entirely with the letters and digits of the portable
                 character set.

       hdrcharset
                 The name of the character set used to encode the value
                 field of the gname, linkpath, path, and uname pax
                 extended header records. The entries in the following
                 table are defined to refer to known standards;
                 additional names may be agreed between the originator
                 and the recipient.
               ┌─────────────────────────┬───────────────────────────────┐
               │         <value>         Formal Standard        │
               ├─────────────────────────┼───────────────────────────────┤
               │ ISO-IR 10646 2000 UTF-8 │ ISO/IEC 10646, UTF-8 encoding │
               │ BINARY                  │ None.                         │
               └─────────────────────────┴───────────────────────────────┘

                 If no hdrcharset extended header record is specified,
                 the default character set used to encode all values in
                 extended header records shall be the
                 ISO/IEC 10646‐1:2000 standard UTF‐8 encoding.

                 The BINARY entry indicates that all values recorded in
                 extended headers for affected files are unencoded
                 binary data from the underlying system.

       linkpath  The pathname of a link being created to another file,
                 of any type, previously archived. This record shall
                 override the linkname field in the following ustar
                 header block(s). The following ustar header block shall
                 determine the type of link created. If typeflag of the
                 following header block is 1, it shall be a hard link.
                 If typeflag is 2, it shall be a symbolic link and the
                 linkpath value shall be the contents of the symbolic
                 link. The pax utility shall translate the name of the
                 link (contents of the symbolic link) from the encoding
                 in the header to the character set appropriate for the
                 local file system. When used in write or copy mode, pax
                 shall include a linkpath extended header record for
                 each link whose pathname cannot be represented entirely
                 with the members of the portable character set other
                 than NUL.

       mtime     The file modification time of the following file(s),
                 equivalent to the value of the st_mtime member of the
                 stat structure for a file, as described in the stat()
                 function. This record shall override the mtime field in
                 the following header block(s). The modification time
                 shall be restored if the process has appropriate
                 privileges required to do so. The format of the <value>
                 shall be as described in pax Extended Header File
                 Times.

       path      The pathname of the following file(s). This record
                 shall override the name and prefix fields in the
                 following header block(s). The pax utility shall
                 translate the pathname of the file from the encoding in
                 the header to the character set appropriate for the
                 local file system.

                 When used in write or copy mode, pax shall include a
                 path extended header record for each file whose
                 pathname cannot be represented entirely with the
                 members of the portable character set other than NUL.

       realtime.any
                 The keywords prefixed by ``realtime.'' are reserved for
                 future standardization.

       security.any
                 The keywords prefixed by ``security.'' are reserved for
                 future standardization.

       size      The size of the file in octets, expressed as a decimal
                 number using digits from the ISO/IEC 646:1991 standard.
                 This record shall override the size field in the
                 following header block(s). When used in write or copy
                 mode, pax shall include a size extended header record
                 for each file with a size value greater than 8589934591
                 (octal 77777777777).

       uid       The user ID of the file owner, expressed as a decimal
                 number using digits from the ISO/IEC 646:1991 standard.
                 This record shall override the uid field in the
                 following header block(s). When used in write or copy
                 mode, pax shall include a uid extended header record
                 for each file whose owner ID is greater than 2097151
                 (octal 7777777).

       uname     The owner of the following file(s), formatted as a user
                 name in the user database. This record shall override
                 the uid and uname fields in the following header
                 block(s), and any uid extended header record. When used
                 in read, copy, or list mode, pax shall translate the
                 name from the encoding in the header record to the
                 character set appropriate for the user database on the
                 receiving system. If any of the characters cannot be
                 translated, and if neither the -oinvalid=UTF‐8 option
                 nor the -oinvalid=binary option is specified, the
                 results are implementation-defined.  When used in write
                 or copy mode, pax shall include a uname extended header
                 record for each file whose user name cannot be
                 represented entirely with the letters and digits of the
                 portable character set.

       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 -o option-
       argument) overrides or deletes a corresponding field in the ustar
       header block, pax shall ignore the contents of that header block
       field.

       Unlike the ustar header block fields, NULs shall not delimit
       <value>s; all characters within the <value> field shall be
       considered data for the field. None of the length limitations of
       the ustar header block fields in Table 4-14, ustar Header Block
       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 pax is used in read or list modes,
       it shall determine a file attribute in the following sequence:

        1. If -odelete=keyword-prefix is used, the affected attributes
           shall be determined from step 7., if applicable, or ignored
           otherwise.

        2. If -okeyword:= is used, the affected attributes shall be
           ignored.

        3. If -okeyword:=value is used, the affected attribute shall be
           assigned the value.

        4. If there is a typeflag x 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 -okeyword=value is used, the affected attribute shall be
           assigned the value.

        6. If there is a typeflag g 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 precedence.

        7. Otherwise, the attribute shall be determined from the ustar
           header block.

   pax Extended Header File Times
       The pax utility shall write an mtime record for each file in
       write or copy modes if the file's modification time cannot be
       represented exactly in the ustar header logical record described
       in ustar Interchange Format.  This can occur if the time is out
       of ustar 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 subsecond timing granularity, where the first digit is
       tenths of a second and each subsequent digit is a tenth of the
       previous digit. In read or copy mode, the pax utility shall
       truncate the time of a file to the greatest value that is not
       greater than the input header file time. In write or copy mode,
       the pax utility shall output a time exactly if it can be
       represented exactly as a decimal number, and otherwise shall
       generate only enough digits so that the same time shall be
       recovered if the file is extracted on a system whose underlying
       implementation supports the same time granularity.

   ustar Interchange Format
       A ustar archive tape or file shall contain a series of logical
       records. Each logical record shall be a fixed-size logical record
       of 512 octets (see below). Although this format may be thought of
       as being stored on 9-track industry-standard 12.7 mm (0.5 in)
       magnetic tape, other types of transportable media are not
       excluded. 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 logical records may be grouped for physical I/O operations,
       as described under the -bblocksize and -x ustar options. Each
       group of logical records may be written with a single operation
       equivalent to the write() function. On magnetic tape, the result
       of this write shall be a single tape physical block. The last
       physical block shall always be the full size, so logical records
       after the two zero logical records may contain undefined data.

       The header logical record shall be structured as shown in the
       following table. All lengths and offsets are in decimal.

                        Table 4-14: ustar Header Block
              ┌────────────┬──────────────┬────────────────────┐
              │ Field Name Octet Offset Length (in Octets) │
              ├────────────┼──────────────┼────────────────────┤
              │ name       │       0      │        100         │
              │ mode       │     100      │          8         │
              │ uid        │     108      │          8         │
              │ gid        │     116      │          8         │
              │ size       │     124      │         12         │
              │ mtime      │     136      │         12         │
              │ chksum     │     148      │          8         │
              │ typeflag   │     156      │          1         │
              │ linkname   │     157      │        100         │
              │ magic      │     257      │          6         │
              │ version    │     263      │          2         │
              │ uname      │     265      │         32         │
              │ gname      │     297      │         32         │
              │ devmajor   │     329      │          8         │
              │ devminor   │     337      │          8         │
              │ prefix     │     345      │        155         │
              └────────────┴──────────────┴────────────────────┘

       All characters in the header logical record shall be represented
       in the coded character set of the ISO/IEC 646:1991 standard. For
       maximum portability between implementations, names should be
       selected from characters represented by the portable filename
       character set as octets with the most significant bit zero. If an
       implementation supports the use of characters outside of <slash>
       and the portable filename character set in names for files,
       users, and groups, one or more implementation-defined encodings
       of these characters shall be provided for interchange purposes.

       However, the pax utility shall never create filenames on the
       local system that cannot be accessed via the procedures described
       in POSIX.1‐2008. If a filename is found on the medium that would
       create an invalid filename, it is implementation-defined whether
       the data from the file is stored on the file hierarchy and under
       what name it is stored. The pax utility may choose to ignore
       these files as long as it produces an error indicating that the
       file is being ignored.

       Each field within the header logical record is contiguous; that
       is, there is no padding used. Each character on the archive
       medium shall be stored contiguously.

       The fields magic, uname, and gname are character strings each
       terminated by a NUL character. The fields name, linkname, and
       prefix are NUL-terminated character strings except when all
       characters in the array contain non-NUL characters including the
       last character. The version field is two octets containing the
       characters "00" (zero-zero). The typeflag contains a single
       character. All other fields are leading zero-filled octal numbers
       using digits from the ISO/IEC 646:1991 standard IRV. Each numeric
       field is terminated by one or more <space> or NUL characters.

       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 NUL), by concatenating prefix
       (up to the first NUL character), a <slash> character, and name;
       otherwise, name is used alone. In either case, name is terminated
       at the first NUL character. If prefix begins with a NUL
       character, it shall be ignored. In this manner, pathnames of at
       most 256 characters can be supported. If a pathname does not fit
       in the space provided, pax shall notify the user of the error,
       and shall not store any part of the file—header or data—on the
       medium.

       The linkname field, described below, shall not use the prefix to
       produce a pathname. As such, a linkname is limited to 100
       characters. If the name does not fit in the space provided, pax
       shall notify the user of the error, and shall not attempt to
       store the link on the medium.

       The mode field provides 12 bits encoded in the ISO/IEC 646:1991
       standard octal digit representation.  The encoded bits shall
       represent the following values:

                            Table: ustar mode Field
┌───────────┬──────────────────┬─────────────────────────────────────────────────┐
│ Bit Value POSIX.1‐2008 Bit Description                   │
├───────────┼──────────────────┼─────────────────────────────────────────────────┤
│   04000   │ S_ISUID          │ Set UID on execution.                           │
│   02000   │ S_ISGID          │ Set GID on execution.                           │
│   01000   │ <reserved>       │ Reserved for future standardization.            │
│   00400   │ S_IRUSR          │ Read permission for file owner class.           │
│   00200   │ S_IWUSR          │ Write permission for file owner class.          │
│   00100   │ S_IXUSR          │ Execute/search permission for file owner class. │
│   00040   │ S_IRGRP          │ Read permission for file group class.           │
│   00020   │ S_IWGRP          │ Write permission for file group class.          │
│   00010   │ S_IXGRP          │ Execute/search permission for file group class. │
│   00004   │ S_IROTH          │ Read permission for file other class.           │
│   00002   │ S_IWOTH          │ Write permission for file other class.          │
│   00001   │ S_IXOTH          │ Execute/search permission for file other class. │
└───────────┴──────────────────┴─────────────────────────────────────────────────┘

       When appropriate privileges are required to set one of these mode
       bits, and the user restoring the files from the archive does not
       have appropriate privileges, the mode bits for which the user
       does not have appropriate privileges shall be ignored. Some of
       the mode bits in the archive format are not mentioned elsewhere
       in this volume of POSIX.1‐2017. If the implementation does not
       support those bits, they may be ignored.

       The uid and gid fields are the user and group ID of the owner and
       group of the file, respectively.

       The size field is the size of the file in octets. If the typeflag
       field is set to specify a file to be of type 1 (a link) or 2 (a
       symbolic link), the size field shall be specified as zero. If the
       typeflag field is set to specify a file of type 5 (directory),
       the size field shall be interpreted as described under the
       definition of that record type. No data logical records are
       stored for types 1, 2, or 5.  If the typeflag field is set to 3
       (character special file), 4 (block special file), or 6 (FIFO),
       the meaning of the size field is unspecified by this volume of
       POSIX.1‐2017, and no data logical records shall be stored on the
       medium. Additionally, for type 6, the size field shall be ignored
       when reading. If the typeflag field is set to any other value,
       the number of logical records written following the header shall
       be (size+511)/512, ignoring any fraction in the result of the
       division.

       The mtime field shall be the modification time of the file at the
       time it was archived. It is the ISO/IEC 646:1991 standard
       representation of the octal value of the modification time
       obtained from the stat() function.

       The chksum field shall be the ISO/IEC 646:1991 standard IRV
       representation of the octal value of the simple sum of all octets
       in the header logical record. Each octet in the header shall be
       treated as an unsigned value. These values shall be added to an
       unsigned integer, initialized to zero, the precision of which is
       not less than 17 bits. When calculating the checksum, the chksum
       field is treated as if it were all <space> characters.

       The typeflag field specifies the type of file archived. If a
       particular implementation does not recognize the type, or the
       user does not have appropriate privileges to create that type,
       the file shall be extracted as if it were a regular file if the
       file type is defined to have a meaning for the size field that
       could cause data logical records to be written on the medium (see
       the previous description for size).  If conversion to a regular
       file occurs, the pax utility shall produce an error indicating
       that the conversion took place. All of the typeflag fields shall
       be coded in the ISO/IEC 646:1991 standard IRV:

       0       Represents a regular file. For backwards-compatibility, a
               typeflag value of binary zero ('\0') should be recognized
               as meaning a regular file when extracting files from the
               archive. Archives written with this version of the
               archive file format create regular files with a typeflag
               value of the ISO/IEC 646:1991 standard IRV '0'.

       1       Represents a file linked to another file, of any type,
               previously archived. Such files are identified by having
               the same device and file serial numbers, and pathnames
               that refer to different directory entries. All such files
               shall be archived as linked files.  The linked-to name is
               specified in the linkname field with a NUL-character
               terminator if it is less than 100 octets in length.

       2       Represents a symbolic link. The contents of the symbolic
               link shall be stored in the linkname field.

       3,4     Represent character special files and block special files
               respectively.  In this case the devmajor and devminor
               fields shall contain information defining the device, the
               format of which is unspecified by this volume of
               POSIX.1‐2017. Implementations may map the device
               specifications to their own local specification or may
               ignore the entry.

       5       Specifies a directory or subdirectory. On systems where
               disk allocation is performed on a directory basis, the
               size field shall contain the maximum number of octets
               (which may be rounded to the nearest disk block
               allocation unit) that the directory may hold.  A size
               field of zero indicates no such limiting. Systems that do
               not support limiting in this manner should ignore the
               size field.

       6       Specifies a FIFO special file. Note that the archiving of
               a FIFO file archives the existence of this file and not
               its contents.

       7       Reserved to represent a file to which an implementation
               has associated some high-performance attribute.
               Implementations without such extensions should treat this
               file as a regular file (type 0).

       A‐Z     The letters 'A' to 'Z', inclusive, are reserved for
               custom implementations. All other values are reserved for
               future versions of this standard.

       It is unspecified whether files with pathnames that refer to the
       same directory entry are archived as linked files or as separate
       files. If they are archived as linked files, this means that
       attempting to extract both pathnames from the resulting archive
       will always cause an error (unless the -u option is used) because
       the link cannot be created.

       It is unspecified whether files with the same device and file
       serial numbers being appended to an archive are treated as linked
       files to members that were in the archive before the append.

       Attempts to archive a socket shall produce a diagnostic message
       when ustar interchange format is used, but may be allowed when
       pax interchange format is used. Handling of other file types is
       implementation-defined.

       The magic field is the specification that this archive was output
       in this archive format. If this field contains ustar (the five
       characters from the ISO/IEC 646:1991 standard IRV shown followed
       by NUL), the uname and gname fields shall contain the
       ISO/IEC 646:1991 standard IRV representation of the owner and
       group of the file, respectively (truncated to fit, if necessary).
       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.

   cpio Interchange Format
       The octet-oriented cpio 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.

       An archive may be recorded as a series of fixed-size blocks of
       octets.  This blocking shall be used only to make physical I/O
       more efficient.  The last group of blocks shall always be at the
       full size.

       For the octet-oriented cpio archive format, the individual entry
       information shall be in the order indicated and described by the
       following table; see also the <cpio.h> header.

                 Table 4-16: Octet-Oriented cpio Archive Entry
       ┌──────────────────────┬────────────────────┬─────────────────┐
       │  Header Field Name   Length (in Octets) Interpreted as  │
       ├──────────────────────┼────────────────────┼─────────────────┤
       │ c_magic              │          6         │ Octal number    │
       │ c_dev                │          6         │ Octal number    │
       │ c_ino                │          6         │ Octal number    │
       │ c_mode               │          6         │ Octal number    │
       │ c_uid                │          6         │ Octal number    │
       │ c_gid                │          6         │ Octal number    │
       │ c_nlink              │          6         │ Octal number    │
       │ c_rdev               │          6         │ Octal number    │
       │ c_mtime              │         11         │ Octal number    │
       │ c_namesize           │          6         │ Octal number    │
       │ c_filesize           │         11         │ Octal number    │
       ├──────────────────────┼────────────────────┼─────────────────┤
       │ Filename Field Name  Length       Interpreted as  │
       ├──────────────────────┴────────────────────┴─────────────────┤
       │ c_name                 c_namesize           Pathname string │
       ├──────────────────────┬────────────────────┬─────────────────┤
       │ File Data Field Name Length       Interpreted as  │
       ├──────────────────────┴────────────────────┴─────────────────┤
       │ c_filedata             c_filesize           Data            │
       └─────────────────────────────────────────────────────────────┘

   cpio Header
       For each file in the archive, a header as defined previously
       shall be written. The information in the header fields is written
       as streams of the ISO/IEC 646:1991 standard characters
       interpreted as octal numbers. The octal numbers shall be extended
       to the necessary length by appending the ISO/IEC 646:1991
       standard IRV zeros at the most-significant-digit end of the
       number; the result is written to the most-significant digit of
       the stream of octets first.  The fields shall be interpreted as
       follows:

       c_magic   Identify the archive as being a transportable archive
                 by containing the identifying value "070707".

       c_dev, c_ino
                 Contains values that uniquely identify the file within
                 the archive (that is, no files contain the same pair of
                 c_dev and c_ino values unless they are links to the
                 same file). The values shall be determined in an
                 unspecified manner.

       c_mode    Contains the file type and access permissions as
                 defined in the following table.

                        Table 4-17: Values for cpio c_mode Field
              ───┬───────────────────────┬─────────┬──────────────────────  │
                F│ile Permissions Name    │Value     Indicates           │
              ───┼───────────────────────┼─────────┼──────────────────────  │
                C│_IRUSR                  │000400   R│ead by owner             │
                C│_IWUSR                  │000200   W│rite by owner            │
                C│_IXUSR                  │000100   E│xecute by owner          │
                C│_IRGRP                  │000040   R│ead by group             │
                C│_IWGRP                  │000020   W│rite by group            │
                C│_IXGRP                  │000010   E│xecute by group          │
                C│_IROTH                  │000004   R│ead by others            │
                C│_IWOTH                  │000002   W│rite by others           │
                C│_IXOTH                  │000001   E│xecute by others         │
                C│_ISUID                  │004000   S│et uid                   │
                C│_ISGID                  │002000   S│et gid                   │
                C│_ISVTX                  │001000   R│eserved                  │
              ───┼───────────────────────┼─────────┼──────────────────────  │
                 │ File Type Name        │Value     Indicates           │
              ───┼───────────────────────┼─────────┼──────────────────────  │
                C│_ISDIR                  │040000   D│irectory                 │
                C│_ISFIFO                 │010000   F│IFO                      │
                C│_ISREG                 0│100000   R│egular file              │
                C│_ISLNK                 0│120000   S│ymbolic link             │
                 │                       │         │                        │
                 │ C_ISBLK               │  060000 │ Block special file     │
                 │ C_ISCHR               │  020000 │ Character special file │
                 │ C_ISSOCK              │ 0140000 │ Socket                 │
                 │                       │         │                        │
                 │ C_ISCTG               │ 0110000 │ Reserved               │
                 └───────────────────────┴─────────┴────────────────────────┘

                 Directories, FIFOs, symbolic links, and regular files
                 shall be supported on a system conforming to this
                 volume of POSIX.1‐2017; additional values defined
                 previously are reserved for compatibility with existing
                 systems.  Additional file types may be supported;
                 however, such files should not be written to archives
                 intended to be transported to other systems.

       c_uid     Contains the user ID of the owner.

       c_gid     Contains the group ID of the group.

       c_nlink   Contains a number greater than or equal to the number
                 of links in the archive referencing the file. If the -a
                 option is used to append to a cpio archive, then the
                 pax utility need not account for the files in the
                 existing part of the archive when calculating the
                 c_nlink values for the appended part of the archive,
                 and need not alter the c_nlink values in the existing
                 part of the archive if additional files with the same
                 c_dev and c_ino values are appended to the archive.

       c_rdev    Contains implementation-defined information for
                 character or block special files.

       c_mtime   Contains the latest time of modification of the file at
                 the time the archive was created.

       c_namesize
                 Contains the length of the pathname, including the
                 terminating NUL character.

       c_filesize
                 Contains the length in octets of the data section
                 following the header structure.

   cpio Filename
       The c_name field shall contain the pathname of the file. The
       length of this field in octets is the value of c_namesize.

       If a filename is found on the medium that would create an invalid
       pathname, it is implementation-defined whether the data from the
       file is stored on the file hierarchy and under what name it is
       stored.

       All characters shall be represented in the ISO/IEC 646:1991
       standard IRV. For maximum portability between implementations,
       names should be selected from characters represented by the
       portable filename character set as octets with the most
       significant bit zero. If an implementation supports the use of
       characters outside the portable filename character set in names
       for files, users, and groups, one or more implementation-defined
       encodings of these characters shall be provided for interchange
       purposes. However, the pax utility shall never create filenames
       on the local system that cannot be accessed via the procedures
       described previously in this volume of POSIX.1‐2017. If a
       filename is found on the medium that would create an invalid
       filename, it is implementation-defined whether the data from the
       file is stored on the local file system and under what name it is
       stored. The pax utility may choose to ignore these files as long
       as it produces an error indicating that the file is being
       ignored.

   cpio File Data
       Following c_name, there shall be c_filesize octets of data.
       Interpretation of such data occurs in a manner dependent on the
       file. For regular files, the data shall consist of the contents
       of the file. For symbolic links, the data shall consist of the
       contents of the symbolic link. If c_filesize is zero, no data
       shall be contained in c_filedata.

       When restoring from an archive:

        *  If the user does not have appropriate privileges to create a
           file of the specified type, pax shall ignore the entry and
           write an error message to standard error.

        *  Only regular files and symbolic links have data to be
           restored. Presuming a regular file meets any selection
           criteria that might be imposed on the format-reading utility
           by the user, such data shall be restored.

        *  If a user does not have appropriate privileges to set a
           particular mode flag, the flag shall be ignored. Some of the
           mode flags in the archive format are not mentioned elsewhere
           in this volume of POSIX.1‐2017. If the implementation does
           not support those flags, they may be ignored.

   cpio Special Entries
       FIFO special files, directories, and the trailer shall be
       recorded with c_filesize equal to zero. Symbolic links shall be
       recorded with c_filesize equal to the length of the contents of
       the symbolic link.  For other special files, c_filesize is
       unspecified by this volume of POSIX.1‐2017. The header for the
       next file entry in the archive shall be written directly after
       the last octet of the file entry preceding it. A header denoting
       the filename TRAILER!!!  shall indicate the end of the archive;
       the contents of octets in the last block of the archive following
       such a header are undefined.

EXIT STATUS         top

       The following exit values shall be returned:

        0    All files were processed successfully.

       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       If pax cannot create a file or a link when reading an archive or
       cannot find a file when writing an archive, or cannot preserve
       the user ID, group ID, or file mode when the -p option is
       specified, a diagnostic message shall be written to standard
       error and a non-zero exit status shall be returned, but
       processing shall continue. In the case where pax cannot create a
       link to a file, pax shall not, by default, create a second copy
       of the file.

       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 S_IRWXU mask set as well as incorrect modification and
       access times.

       The following sections are informative.

APPLICATION USAGE         top

       Caution is advised when using the -a option to append to a cpio
       format archive. If any of the files being appended happen to be
       given the same c_dev and c_ino values as a file in the existing
       part of the archive, then they may be treated as links to that
       file on extraction. Thus, it is risky to use -a with cpio format
       except when it is done on the same system that the original
       archive was created on, and with the same pax utility, and in the
       knowledge that there has been little or no file system activity
       since the original archive was created that could lead to any of
       the files appended being given the same c_dev and c_ino values as
       an unrelated file in the existing part of the archive. Also, when
       (intentionally) appending additional links to a file in the
       existing part of the archive, the c_nlink values in the modified
       archive can be smaller than the number of links to the file in
       the archive, which may mean that the links are not preserved on
       extraction.

       The -p (privileges) option was invented to reconcile differences
       between historical tar and cpio implementations. In particular,
       the two utilities use -m in diametrically opposed ways. The -p
       option also provides a consistent means of extending the ways in
       which future file attributes can be addressed, such as for
       enhanced security systems or high-performance files. Although it
       may seem complex, there are really two modes that are most
       commonly used:

       -p e    ``Preserve everything''. This would be used by the
               historical superuser, someone with all 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-defined 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.

       The one pathname per line format of standard input precludes
       pathnames containing <newline> characters. Although such
       pathnames violate the portable filename guidelines, they may
       exist and their presence may inhibit usage of pax within shell
       scripts. This problem is inherited from historical archive
       programs. The problem can be avoided by listing filename
       arguments on the command line instead of on standard input.

       It is almost certain that appropriate privileges are required for
       pax to accomplish parts of this volume of POSIX.1‐2017.
       Specifically, creating files of type block special or character
       special, restoring file access times unless the files are owned
       by the user (the -t option), or preserving file owner, group, and
       mode (the -p option) all probably require appropriate privileges.

       In read mode, implementations are permitted to overwrite files
       when the archive has multiple members with the same name. This
       may fail if permissions on the first version of the file do not
       permit it to be overwritten.

       The cpio and ustar formats can only support files up to
       8589934592 bytes (8 ∗ 2^30) in size.

       When archives containing binary header information are listed ,
       the filenames printed may cause strange behavior on some
       terminals.

       When all of the following are true:

        1. A file of type directory is being placed into an archive.

        2. The ustar archive format is being used.

        3. The pathname of the directory is less than or equal to 155
           bytes long (it will fit in the prefix field in the ustar
           header block).

        4. The last component of the pathname of the directory is longer
           than 100 bytes long (it will not fit in the name field in the
           ustar header block).

       some implementations of the pax utility will place the entire
       directory pathname in the prefix field, set the name field to an
       empty string, and place the directory in the archive.  Other
       implementations of the pax utility will give an error under these
       conditions because the name field is not large enough to hold the
       last component of the directory name.  This standard allows
       either behavior. However, when extracting a directory from a
       ustar format archive, this standard requires that all
       implementations be able to extract a directory even if the name
       field contains an empty string as long as the prefix field does
       not also contain an empty string.

EXAMPLES         top

       The following command:

           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:

           mkdir newdir
           pax -rw olddir newdir

       copy the olddir directory hierarchy to newdir.

           pax -r -s ',^//*usr//*,,' -f a.pax

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

       Using the option:

           -o listopt="%M %(atime)T %(size)D %(name)s"

       overrides the default output description in Standard Output and
       instead writes:

           -rw-rw--- Jan 12 15:53 2003 1492 /usr/foo/bar

       Using the options:

           -o listopt='%L\t%(size)D\n%.7' \
           -o listopt='(name)s\n%(atime)T\n%T'

       overrides the default output description in Standard Output and
       instead writes:

           /usr/foo/bar -> /tmp   1492
           /usr/fo
           Jan 12 15:53 1991
           Jan 31 15:53 2003

RATIONALE         top

       The pax utility was new for the ISO POSIX‐2:1993 standard. It
       represents a peaceful compromise between advocates of the
       historical tar and cpio utilities.

       A fundamental difference between cpio and tar was in the way
       directories were treated. The cpio utility did not treat
       directories differently from other files, and to select a
       directory and its contents required that each file in the
       hierarchy be explicitly specified. For tar, a directory matched
       every file in the file hierarchy it rooted.

       The pax utility offers both interfaces; by default, directories
       map into the file hierarchy they root. The -d option causes pax
       to skip any file not explicitly referenced, as cpio historically
       did. The tar -style behavior was chosen as the default because it
       was believed that this was the more common usage and because tar
       is the more commonly available interface, as it was historically
       provided on both System V and BSD implementations.

       The data interchange format specification in this volume of
       POSIX.1‐2017 requires that processes with ``appropriate
       privileges'' shall always restore the ownership and permissions
       of extracted files exactly as archived. If viewed from the
       historic equivalence between superuser and ``appropriate
       privileges'', there are two problems with this requirement.
       First, users running as superusers may unknowingly set dangerous
       permissions on extracted files. Second, it is needlessly
       limiting, in that superusers cannot extract files and own them as
       superuser unless the archive was created by the superuser. (It
       should be noted that restoration of ownerships and permissions
       for the superuser, by default, is historical practice in cpio,
       but not in tar.)  In order to avoid these two problems, the pax
       specification has an additional ``privilege'' mechanism, the -p
       option. Only a pax invocation with the privileges needed, and
       which has the -p option set using the e specification character,
       has appropriate privileges to restore full ownership and
       permission information.

       Note also that this volume of POSIX.1‐2017 requires that the file
       ownership and access permissions shall be set, on extraction, in
       the same fashion as the creat() function when provided with the
       mode stored in the archive. This means that the file creation
       mask of the user is applied to the file permissions.

       Users should note that directories may be created by pax while
       extracting files with permissions that are different from those
       that existed at the time the archive was created. When extracting
       sensitive information into a directory hierarchy that no longer
       exists, users are encouraged to set their file creation mask
       appropriately to protect these files during extraction.

       The table of contents output is written to standard output to
       facilitate pipeline processing.

       An early proposal had hard links displaying for all pathnames.
       This was removed because it complicates the output of the case
       where -v is not specified and does not match historical cpio
       usage. The hard-link information is available in the -v display.

       The description of the -l option allows implementations to make
       hard links to symbolic links.  Earlier versions of this standard
       did not specify any way to create a hard link to a symbolic link,
       but many implementations provided this capability as an
       extension. If there are hard links to symbolic links when an
       archive is created, the implementation is required to archive the
       hard link in the archive (unless -H or -L is specified). When in
       read mode and in copy mode, implementations supporting hard links
       to symbolic links should use them when appropriate.

       The archive formats inherited from the POSIX.1‐1990 standard have
       certain restrictions that have been brought along from historical
       usage. For example, there are restrictions on the length of
       pathnames stored in the archive.  When pax is used in copy(-rw)
       mode (copying directory hierarchies), the ability to use
       extensions from the -xpax format overcomes these restrictions.

       The default blocksize value of 5120 bytes for cpio was selected
       because it is one of the standard block-size values for cpio, set
       when the -B option is specified. (The other default block-size
       value for cpio is 512 bytes, and this was considered to be too
       small.) The default block value of 10240 bytes for tar was
       selected because that is the standard block-size value for BSD
       tar.  The maximum block size of 32256 bytes (215-512 bytes) is
       the largest multiple of 512 bytes that fits into a signed 16-bit
       tape controller transfer register. There are known limitations in
       some historical systems that would prevent larger blocks from
       being accepted. Historical values were chosen to improve
       compatibility with historical scripts using dd or similar
       utilities to manipulate archives. Also, default block sizes for
       any file type other than character special file has been deleted
       from this volume of POSIX.1‐2017 as unimportant and not likely to
       affect the structure of the resulting archive.

       Implementations are permitted to modify the block-size value
       based on the archive format or the device to which the archive is
       being written. This is to provide implementations with the
       opportunity to take advantage of special types of devices, and it
       should not be used without a great deal of consideration as it
       almost certainly decreases archive portability.

       The intended use of the -n option was to permit extraction of one
       or more files from the archive without processing the entire
       archive. This was viewed by the standard developers as offering
       significant performance advantages over historical
       implementations. The -n option in early proposals had three
       effects; the first was to cause special characters in patterns to
       not be treated specially. The second was to cause only the first
       file that matched a pattern to be extracted. The third was to
       cause pax to write a diagnostic message to standard error when no
       file was found matching a specified pattern. Only the second
       behavior is retained by this volume of POSIX.1‐2017, for many
       reasons. First, it is in general not acceptable for a single
       option to have multiple effects. Second, the ability to make
       pattern matching characters act as normal characters is useful
       for parts of pax other than file extraction. Third, a finer
       degree of control over the special characters is useful because
       users may wish to normalize only a single special character in a
       single filename. Fourth, given a more general escape mechanism,
       the previous behavior of the -n option can be easily obtained
       using the -s option or a sed script. Finally, writing a
       diagnostic message when a pattern specified by the user is
       unmatched by any file is useful behavior in all cases.

       In this version, the -n was removed from the copy mode synopsis
       of pax; it is inapplicable because there are no pattern operands
       specified in this mode.

       There is another method than pax for copying subtrees in
       POSIX.1‐2008 described as part of the cp utility. Both methods
       are historical practice: cp provides a simpler, more intuitive
       interface, while pax offers a finer granularity of control. Each
       provides additional functionality to the other; in particular,
       pax maintains the hard-link structure of the hierarchy while cp
       does not. It is the intention of the standard developers that the
       results be similar (using appropriate option combinations in both
       utilities). The results are not required to be identical; there
       seemed insufficient gain to applications to balance the
       difficulty of implementations having to guarantee that the
       results would be exactly identical.

       A single archive may span more than one file. It is suggested
       that implementations provide informative messages to the user on
       standard error whenever the archive file is changed.

       The -d option (do not create intermediate directories not listed
       in the archive) found in early proposals was originally provided
       as a complement to the historic -d option of cpio.  It has been
       deleted.

       The -s option in early proposals specified a subset of the
       substitution command from the ed utility. As there was no reason
       for only a subset to be supported, the -s option is now
       compatible with the current ed specification. Since the delimiter
       can be any non-null character, the following usage with single
       <space> characters is valid:

           pax -s " foo bar " ...

       The -t description is worded so as to note that this may cause
       the access time update caused by some other activity (which
       occurs while the file is being read) to be overwritten.

       The default behavior of pax with regard to file modification
       times is the same as historical implementations of tar.  It is
       not the historical behavior of cpio.

       Because the -i option uses /dev/tty, utilities without a
       controlling terminal are not able to use this option.

       The -y option, found in early proposals, has been deleted because
       a line containing a single <period> for the -i option has
       equivalent functionality. The special lines for the -i option (a
       single <period> and the empty line) are historical practice in
       cpio.

       In early drafts, a -echarmap option was included to increase
       portability of files between systems using different coded
       character sets. This option was omitted because it was apparent
       that consensus could not be formed for it. In this version, the
       use of UTF‐8 should be an adequate substitute.

       The ISO POSIX‐2:1993 standard and ISO POSIX‐1 standard
       requirements for pax, however, made it very difficult to create a
       single archive containing files created using extended characters
       provided by different locales.  This version adds the hdrcharset
       keyword to make it possible to archive files in these cases
       without dropping files due to translation errors.

       Translating filenames and other attributes from a locale's
       encoding to UTF‐8 and then back again can lose information, as
       the resulting filename might not be byte-for-byte equivalent to
       the original. To avoid this problem, users can specify the -o
       hdrcharset=binary option, which will cause the resulting archive
       to use binary format for all names and attributes. Such archives
       are not portable among hosts that use different native encodings
       (e.g., EBCDIC versus ASCII-based encodings), but they will allow
       interchange among the vast majority of POSIX file systems in
       practical use. Also, the -o hdrcharset=binary option will cause
       pax in copy mode to behave more like other standard utilities
       such as cp.

       If the values specified by the -o exthdr.name=value, -o
       globexthdr.name=value, or by $TMPDIR (if -o globexthdr.name is
       not specified) require a character encoding other than that
       described in the ISO/IEC 646:1991 standard, a path extended
       header record will have to be created for the file. If a
       hdrcharset extended header record is active for such headers, it
       will determine the codeset used for the value field in these
       extended path header records. These path extended header records
       always need to be created when writing an archive even if
       hdrcharset=binary has been specified and would contain the same
       (binary) data that appears in the ustar header record prefix and
       name fields. (In other words, an extended header path record is
       always required to be generated if the prefix or name fields
       contain non-ASCII characters even when hdrcharset=binary is also
       in effect for that file.)

       The -k option was added to address international concerns about
       the dangers involved in the character set transformations of -e
       (if the target character set were different from the source, the
       filenames might be transformed into names matching existing
       files) and also was made more general to protect files
       transferred between file systems with different {NAME_MAX} values
       (truncating a filename on a smaller system might also
       inadvertently overwrite existing files). As stated, it prevents
       any overwriting, even if the target file is older than the
       source. This version adds more granularity of options to solve
       this problem by introducing the -oinvalid=option—specifically the
       UTF‐8 and binary actions. (Note that an existing file is still
       subject to overwriting in this case. The -k option closes that
       loophole.)

       Some of the file characteristics referenced in this volume of
       POSIX.1‐2017 might not be supported by some archive formats. For
       example, neither the tar nor cpio formats contain the file access
       time. For this reason, the e specification character has been
       provided, intended to cause all file characteristics specified in
       the archive to be retained.

       It is required that extracted directories, by default, have their
       access and modification times and permissions set to the values
       specified in the archive. This has obvious problems in that the
       directories are almost certainly modified after being extracted
       and that directory permissions may not permit file creation. One
       possible solution is to create directories with the mode
       specified in the archive, as modified by the umask of the user,
       with sufficient permissions to allow file creation. After all
       files have been extracted, pax would then reset the access and
       modification times and permissions as necessary.

       The list-mode formatting description borrows heavily from the one
       defined by the printf utility. However, since there is no
       separate operand list to get conversion arguments, the format was
       extended to allow specifying the name of the conversion argument
       as part of the conversion specification.

       The T conversion specifier allows time fields to be displayed in
       any of the date formats. Unlike the ls utility, pax does not
       adjust the format when the date is less than six months in the
       past. This makes parsing the output more predictable.

       The D conversion specifier handles the ability to display the
       major/minor or file size, as with ls, by using %-8(size)D.

       The L conversion specifier handles the ls display for symbolic
       links.

       Conversion specifiers were added to generate existing known types
       used for ls.

   pax Interchange Format
       The new POSIX data interchange format was developed primarily to
       satisfy international concerns that the ustar and cpio formats
       did not provide for file, user, and group names encoded in
       characters outside a subset of the ISO/IEC 646:1991 standard. The
       standard developers realized that this new POSIX data interchange
       format should be very extensible because there were other
       requirements they foresaw in the near future:

        *  Support international character encodings and locale
           information

        *  Support security information (ACLs, and so on)

        *  Support future file types, such as realtime or contiguous
           files

        *  Include data areas for implementation use

        *  Support systems with words larger than 32 bits and timers
           with subsecond granularity

       The following were not goals for this format because these are
       better handled by separate utilities or are inappropriate for a
       portable format:

        *  Encryption

        *  Compression

        *  Data translation between locales and codesets

        *  inode storage

       The format chosen to support the goals is an extension of the
       ustar format. Of the two formats previously available, only the
       ustar format was selected for extensions because:

        *  It was easier to extend in an upwards-compatible way. It
           offered version flags and header block type fields with room
           for future standardization. The cpio format, while possessing
           a more flexible file naming methodology, could not be
           extended without breaking some theoretical implementation or
           using a dummy filename that could be a legitimate filename.

        *  Industry experience since the original ``tar wars'' fought in
           developing the ISO POSIX‐1 standard has clearly been in favor
           of the ustar format, which is generally the default output
           format selected for pax implementations on new systems.

       The new format was designed with one additional goal in mind:
       reasonable behavior when an older tar or pax utility happened to
       read an archive. Since the POSIX.1‐1990 standard mandated that a
       ``format-reading utility'' had to treat unrecognized typeflag
       values as regular files, this allowed the format to include all
       the extended information in a pseudo-regular file that preceded
       each real file. An option is given that allows the archive
       creator to set up reasonable names for these files on the older
       systems. Also, the normative text suggests that reasonable file
       access values be used for this ustar header block. Making these
       header files inaccessible for convenient reading and deleting
       would not be reasonable. File permissions of 600 or 700 are
       suggested.

       The ustar typeflag field was used to accommodate the additional
       functionality of the new format rather than magic or version
       because the POSIX.1‐1990 standard (and, by reference, the
       previous version of pax), mandated the behavior of the format-
       reading utility when it encountered an unknown typeflag, but was
       silent about the other two fields.

       Early proposals for the first version of this standard contained
       a proposed archive format that was based on compatibility with
       the standard for tape files (ISO 1001, similar to the format used
       historically on many mainframes and minicomputers). This format
       was overly complex and required considerable overhead in volume
       and header records. Furthermore, the standard developers felt
       that it would not be acceptable to the community of POSIX
       developers, so it was later changed to be a format more closely
       related to historical practice on POSIX systems.

       The prefix and name split of pathnames in ustar was replaced by
       the single path extended header record for simplicity.

       The concept of a global extended header (typeflagg) was
       controversial. If this were applied to an archive being recorded
       on magnetic tape, a few unreadable blocks at the beginning of the
       tape could be a serious problem; a utility attempting to extract
       as many files as possible from a damaged archive could lose a
       large percentage of file header information in this case.
       However, if the archive were on a reliable medium, such as a CD‐
       ROM, the global extended header offers considerable potential
       size reductions by eliminating redundant information. Thus, the
       text warns against using the global method for unreliable media
       and provides a method for implanting global information in the
       extended header for each file, rather than in the typeflag g
       records.

       No facility for data translation or filtering on a per-file basis
       is included because the standard developers could not invent an
       interface that would allow this in an efficient manner. If a
       filter, such as encryption or compression, is to be applied to
       all the files, it is more efficient to apply the filter to the
       entire archive as a single file. The standard developers
       considered interfaces that would invoke a shell script for each
       file going into or out of the archive, but the system overhead in
       this approach was considered to be too high.

       One such approach would be to have filter= records that give a
       pathname for an executable. When the program is invoked, the file
       and archive would be open for standard input/output and all the
       header fields would be available as environment variables or
       command-line arguments. The standard developers did discuss such
       schemes, but they were omitted from POSIX.1‐2008 due to concerns
       about excessive overhead. Also, the program itself would need to
       be in the archive if it were to be used portably.

       There is currently no portable means of identifying the character
       set(s) used for a file in the file system. Therefore, pax has not
       been given a mechanism to generate charset records automatically.
       The only portable means of doing this is for the user to write
       the archive using the -ocharset=string command line option. This
       assumes that all of the files in the archive use the same
       encoding. The ``implementation-defined'' text is included to
       allow for a system that can identify the encodings used for each
       of its files.

       The table of standards that accompanies the charset record
       description is acknowledged to be very limited. Only a limited
       number of character set standards is reasonable for maximal
       interchange. Any character set is, of course, possible by prior
       agreement. It was suggested that EBCDIC be listed, but it was
       omitted because it is not defined by a formal standard. Formal
       standards, and then only those with reasonably large followings,
       can be included here, simply as a matter of practicality. The
       <value>s represent names of officially registered character sets
       in the format required by the ISO 2375:1985 standard.

       The normal <comma> or <blank>-separated list rules are not
       followed in the case of keyword options to allow ease of argument
       parsing for getopts.

       Further information on character encodings is in pax Archive
       Character Set Encoding/Decoding.

       The standard developers have reserved keyword name space for
       vendor extensions. It is suggested that the format to be used is:

           VENDOR.keyword

       where VENDOR is the name of the vendor or organization in all
       uppercase letters. It is further suggested that the keyword
       following the <period> be named differently than any of the
       standard keywords so that it could be used for future
       standardization, if appropriate, by omitting the VENDOR prefix.

       The <length> field in the extended header record was included to
       make it simpler to step through the records, even if a record
       contains an unknown format (to a particular pax) with complex
       interactions of special characters. It also provides a minor
       integrity checkpoint within the records to aid a program
       attempting to recover files from a damaged archive.

       There are no extended header versions of the devmajor and
       devminor fields because the unspecified format ustar header field
       should be sufficient. If they are not, vendor-specific extended
       keywords (such as VENDOR.devmajor) should be used.

       Device and i-number labeling of files was not adopted from cpio;
       files are interchanged strictly on a symbolic name basis, as in
       ustar.

       Just as with the ustar format descriptions, the new format makes
       no special arrangements for multi-volume archives. Each of the
       pax archive types is assumed to be inside a single POSIX file and
       splitting that file over multiple volumes (diskettes, tape
       cartridges, and so on), processing their labels, and mounting
       each in the proper sequence are considered to be implementation
       details that cannot be described portably.

       The pax format is intended for interchange, not only for backup
       on a single (family of) systems. It is not as densely packed as
       might be possible for backup:

        *  It contains information as coded characters that could be
           coded in binary.

        *  It identifies extended records with name fields that could be
           omitted in favor of a fixed-field layout.

        *  It translates names into a portable character set and
           identifies locale-related information, both of which are
           probably unnecessary for backup.

       The requirements on restoring from an archive are slightly
       different from the historical wording, allowing for non-
       monolithic privilege to bring forward as much as possible. In
       particular, attributes such as ``high performance file'' might be
       broadly but not universally granted while set-user-ID or chown()
       might be much more restricted. There is no implication in
       POSIX.1‐2008 that the security information be honored after it is
       restored to the file hierarchy, in spite of what might be
       improperly inferred by the silence on that topic. That is a topic
       for another standard.

       Links are recorded in the fashion described here because a link
       can be to any file type. It is desirable in general to be able to
       restore part of an archive selectively and restore all of those
       files completely. If the data is not associated with each link,
       it is not possible to do this. However, the data associated with
       a file can be large, and when selective restoration is not
       needed, this can be a significant burden.  The archive is
       structured so that files that have no associated data can always
       be restored by the name of any link name of any link, and the
       user may choose whether data is recorded with each instance of a
       file that contains data. The format permits mixing of both types
       of links in a single archive; this can be done for special needs,
       and pax is expected to interpret such archives on input properly,
       despite the fact that there is no pax option that would force
       this mixed case on output. (When -o linkdata is used, the output
       must contain the duplicate data, but the implementation is free
       to include it or omit it when -o linkdata is not used.)

       The time values are included as extended header records for those
       implementations needing more than the eleven octal digits allowed
       by the ustar format. Portable file timestamps cannot be negative.
       If pax encounters a file with a negative timestamp in copy or
       write mode, it can reject the file, substitute a non-negative
       timestamp, or generate a non-portable timestamp with a leading
       '-'.  Even though some implementations can support finer file-
       time granularities than seconds, the normative text requires
       support only for seconds since the Epoch because the ISO POSIX‐1
       standard states them that way. The ustar format includes only
       mtime; the new format adds atime and ctime for symmetry. The
       atime access time restored to the file system will be affected by
       the -p a and -p e options. The ctime creation time (actually
       inode modification time) is described with appropriate privileges
       so that it can be ignored when writing to the file system. POSIX
       does not provide a portable means to change file creation time.
       Nothing is intended to prevent a non-portable implementation of
       pax from restoring the value.

       The gid, size, and uid extended header records were included to
       allow expansion beyond the sizes specified in the regular tar
       header. New file system architectures are emerging that will
       exhaust the 12-digit size field. There are probably not many
       systems requiring more than 8 digits for user and group IDs, but
       the extended header values were included for completeness,
       allowing overrides for all of the decimal values in the tar
       header.

       The standard developers intended to describe the effective
       results of pax with regard to file ownerships and permissions;
       implementations are not restricted in timing or sequencing the
       restoration of such, provided the results are as specified.

       Much of the text describing the extended headers refers to use in
       ``write or copy modes''. The copy mode references are due to the
       normative text: ``The effect of the copy shall be as if the
       copied files were written to an archive file and then
       subsequently extracted ...''. There is certainly no way to test
       whether pax is actually generating the extended headers in copy
       mode, but the effects must be as if it had.

   pax Archive Character Set Encoding/Decoding
       There is a need to exchange archives of files between systems of
       different native codesets. Filenames, group names, and user names
       must be preserved to the fullest extent possible when an archive
       is read on the receiving platform. Translation of the contents of
       files is not within the scope of the pax utility.

       There will also be the need to represent characters that are not
       available on the receiving platform. These unsupported characters
       cannot be automatically folded to the local set of characters due
       to the chance of collisions. This could result in overwriting
       previous extracted files from the archive or pre-existing files
       on the system.

       For these reasons, the codeset used to represent characters
       within the extended header records of the pax archive must be
       sufficiently rich to handle all commonly used character sets. The
       fields requiring translation include, at a minimum, filenames,
       user names, group names, and link pathnames. Implementations may
       wish to have localized extended keywords that use non-portable
       characters.

       The standard developers considered the following options:

        *  The archive creator specifies the well-defined name of the
           source codeset. The receiver must then recognize the codeset
           name and perform the appropriate translations to the
           destination codeset.

        *  The archive creator includes within the archive the character
           mapping table for the source codeset used to encode extended
           header records.  The receiver must then read the character
           mapping table and perform the appropriate translations to the
           destination codeset.

        *  The archive creator translates the extended header records in
           the source codeset into a canonical form. The receiver must
           then perform the appropriate translations to the destination
           codeset.

       The approach that incorporates the name of the source codeset
       poses the problem of codeset name registration, and makes the
       archive useless to pax archive decoders that do not recognize
       that codeset.

       Because parts of an archive may be corrupted, the standard
       developers felt that including the character map of the source
       codeset was too fragile. The loss of this one key component could
       result in making the entire archive useless. (The difference
       between this and the global extended header decision was that the
       latter has a workaround—duplicating extended header records on
       unreliable media—but this would be too burdensome for large
       character set maps.)

       Both of the above approaches also put an undue burden on the pax
       archive receiver to handle the cross-product of all source and
       destination codesets.

       To simplify the translation from the source codeset to the
       canonical form and from the canonical form to the destination
       codeset, the standard developers decided that the internal
       representation should be a stateless encoding. A stateless
       encoding is one where each codepoint has the same meaning,
       without regard to the decoder being in a specific state. An
       example of a stateful encoding would be the Japanese Shift-JIS;
       an example of a stateless encoding would be the ISO/IEC 646:1991
       standard (equivalent to 7-bit ASCII).

       For these reasons, the standard developers decided to adopt a
       canonical format for the representation of file information
       strings. The obvious, well-endorsed candidate is the
       ISO/IEC 10646‐1:2000 standard (based in part on Unicode), which
       can be used to represent the characters of virtually all
       standardized character sets. The standard developers initially
       agreed upon using UCS2 (16-bit Unicode) as the internal
       representation. This repertoire of characters provides a
       sufficiently rich set to represent all commonly-used codesets.

       However, the standard developers found that the 16-bit Unicode
       representation had some problems. It forced the issue of
       standardizing byte ordering. The 2-byte length of each character
       made the extended header records twice as long for the case of
       strings coded entirely from historical 7-bit ASCII. For these
       reasons, the standard developers chose the UTF‐8 defined in the
       ISO/IEC 10646‐1:2000 standard. This multi-byte representation
       encodes UCS2 or UCS4 characters reliably and deterministically,
       eliminating the need for a canonical byte ordering. In addition,
       NUL octets and other characters possibly confusing to POSIX file
       systems do not appear, except to represent themselves. It was
       realized that certain national codesets take up more space after
       the encoding, due to their placement within the UCS range; it was
       felt that the usefulness of the encoding of the names outweighs
       the disadvantage of size increase for file, user, and group
       names.

       The encoding of UTF‐8 is as follows:

           UCS4 Hex Encoding  UTF-8 Binary Encoding

           00000000-0000007F  0xxxxxxx
           00000080-000007FF  110xxxxx 10xxxxxx
           00000800-0000FFFF  1110xxxx 10xxxxxx 10xxxxxx
           00010000-001FFFFF  11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
           00200000-03FFFFFF  111110xx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx
           04000000-7FFFFFFF  1111110x 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx 10xxxxxx

       where each 'x' represents a bit value from the character being
       translated.

   ustar Interchange Format
       The description of the ustar format reflects numerous
       enhancements over pre-1988 versions of the historical tar
       utility. The goal of these changes was not only to provide the
       functional enhancements desired, but also to retain compatibility
       between new and old versions. This compatibility has been
       retained.  Archives written using the old archive format are
       compatible with the new format.

       Implementors should be aware that the previous file format did
       not include a mechanism to archive directory type files. For this
       reason, the convention of using a filename ending with <slash>
       was adopted to specify a directory on the archive.

       The total size of the name and prefix fields have been set to
       meet the minimum requirements for {PATH_MAX}.  If a pathname will
       fit within the name field, it is recommended that the pathname be
       stored there without the use of the prefix field. Although the
       name field is known to be too small to contain {PATH_MAX}
       characters, the value was not changed in this version of the
       archive file format to retain backwards-compatibility, and
       instead the prefix was introduced. Also, because of the earlier
       version of the format, there is no way to remove the restriction
       on the linkname field being limited in size to just that of the
       name field.

       The size field is required to be meaningful in all implementation
       extensions, although it could be zero. This is required so that
       the data blocks can always be properly counted.

       It is suggested that if device special files need to be
       represented that cannot be represented in the standard format,
       that one of the extension types (AZ) be used, and that the
       additional information for the special file be represented as
       data and be reflected in the size field.

       Attempting to restore a special file type, where it is converted
       to ordinary data and conflicts with an existing filename, need
       not be specially detected by the utility. If run as an ordinary
       user, pax should not be able to overwrite the entries in, for
       example, /dev in any case (whether the file is converted to
       another type or not). If run as a privileged user, it should be
       able to do so, and it would be considered a bug if it did not.
       The same is true of ordinary data files and similarly named
       special files; it is impossible to anticipate the needs of the
       user (who could really intend to overwrite the file), so the
       behavior should be predictable (and thus regular) and rely on the
       protection system as required.

       The value 7 in the typeflag field is intended to define how
       contiguous files can be stored in a ustar archive. POSIX.1‐2008
       does not require the contiguous file extension, but does define a
       standard way of archiving such files so that all conforming
       systems can interpret these file types in a meaningful and
       consistent manner. On a system that does not support extended
       file types, the pax utility should do the best it can with the
       file and go on to the next.

       The file protection modes are those conventionally used by the ls
       utility. This is extended beyond the usage in the ISO POSIX‐2
       standard to support the ``shared text'' or ``sticky'' bit. It is
       intended that the conformance document should not document
       anything beyond the existence of and support of such a mode.
       Further extensions are expected to these bits, particularly with
       overloading the set-user-ID and set-group-ID flags.

   cpio Interchange Format
       The reference to appropriate privileges in the cpio format refers
       to an error on standard output; the ustar format does not make
       comparable statements.

       The model for this format was the historical System V cpio-c data
       interchange format. This model documents the portable version of
       the cpio format and not the binary version. It has the
       flexibility to transfer data of any type described within
       POSIX.1‐2008, yet is extensible to transfer data types specific
       to extensions beyond POSIX.1‐2008 (for example, contiguous
       files). Because it describes existing practice, there is no
       question of maintaining upwards-compatibility.

   cpio Header
       There has been some concern that the size of the c_ino field of
       the header is too small to handle those systems that have very
       large inode numbers. However, the c_ino field in the header is
       used strictly as a hard-link resolution mechanism for archives.
       It is not necessarily the same value as the inode number of the
       file in the location from which that file is extracted.

       The name c_magic is based on historical usage.

   cpio Filename
       For most historical implementations of the cpio utility,
       {PATH_MAX} octets can be used to describe the pathname without
       the addition of any other header fields (the NUL character would
       be included in this count).  {PATH_MAX} is the minimum value for
       pathname size, documented as 256 bytes.  However, an
       implementation may use c_namesize to determine the exact length
       of the pathname. With the current description of the <cpio.h>
       header, this pathname size can be as large as a number that is
       described in six octal digits.

       Two values are documented under the c_mode field values to
       provide for extensibility for known file types:

       0110 000  Reserved for contiguous files. The implementation may
                 treat the rest of the information for this archive like
                 a regular file. If this file type is undefined, the
                 implementation may create the file as a regular file.

       This provides for extensibility of the cpio format while allowing
       for the ability to read old archives. Files of an unknown type
       may be read as ``regular files'' on some implementations.  On a
       system that does not support extended file types, the pax utility
       should do the best it can with the file and go on to the next.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       Chapter 2, Shell Command Language, cp(1p), ed(1p), getopts(1p),
       ls(1p), printf(1p)

       The Base Definitions volume of POSIX.1‐2017, Section 3.169, File
       Mode Bits, Chapter 5, File Format Notation, Chapter 8,
       Environment Variables, Section 12.2, Utility Syntax Guidelines,
       cpio.h(0p), tar.h(0p)

       The System Interfaces volume of POSIX.1‐2017, chown(3p),
       creat(3p), fstatat(3p), mkdir(3p), mkfifo(3p), utime(3p),
       write(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                           PAX(1P)

Pages that refer to this page: cpio.h(0p)tar.h(0p)ar(1p)cp(1p)file(1p)find(1p)ln(1p)