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

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

       ar — create and maintain library archives

SYNOPSIS         top

       ar −d [−v] archive file...
       ar −m [−v] archive file...
       ar −m −a [−v] posname archive file...
       ar −m −b [−v] posname archive file...
       ar −m −i [−v] posname archive file...
       ar −p [−v] [−s] archive [file...]
       ar −q [−cv] archive file...
       ar −r [−cuv] archive file...
       ar −r −a [−cuv] posname archive file...
       ar −r −b [−cuv] posname archive file...
       ar −r −i [−cuv] posname archive file...
       ar −t [−v] [−s] archive [file...]
       ar −x [−v] [−sCT] archive [file...]

DESCRIPTION         top

       The ar utility is part of the Software Development Utilities option.
       The ar utility can be used to create and maintain groups of files
       combined into an archive. Once an archive has been created, new files
       can be added, and existing files in an archive can be extracted,
       deleted, or replaced. When an archive consists entirely of valid
       object files, the implementation shall format the archive so that it
       is usable as a library for link editing (see c99 and fort77).  When
       some of the archived files are not valid object files, the
       suitability of the archive for library use is undefined.  If an
       archive consists entirely of printable files, the entire archive
       shall be printable.
       When ar creates an archive, it creates administrative information
       indicating whether a symbol table is present in the archive. When
       there is at least one object file that ar recognizes as such in the
       archive, an archive symbol table shall be created in the archive and
       maintained by ar; it is used by the link editor to search the
       archive. Whenever the ar utility is used to create or update the
       contents of such an archive, the symbol table shall be rebuilt. The
       −s option shall force the symbol table to be rebuilt.
       All file operands can be pathnames. However, files within archives
       shall be named by a filename, which is the last component of the
       pathname used when the file was entered into the archive. The
       comparison of file operands to the names of files in archives shall
       be performed by comparing the last component of the operand to the
       name of the file in the archive.
       It is unspecified whether multiple files in the archive may be
       identically named. In the case of such files, however, each file and
       posname operand shall match only the first file in the archive having
       a name that is the same as the last component of the operand.

OPTIONS         top

       The ar utility shall conform to the Base Definitions volume of
       POSIX.1‐2008, Section 12.2, Utility Syntax Guidelines, except for
       Guideline 9.
       The following options shall be supported:
       −a        Position new files in the archive after the file named by
                 the posname operand.
       −b        Position new files in the archive before the file named by
                 the posname operand.
       −c        Suppress the diagnostic message that is written to standard
                 error by default when the archive archive is created.
       −C        Prevent extracted files from replacing like-named files in
                 the file system. This option is useful when −T is also
                 used, to prevent truncated filenames from replacing files
                 with the same prefix.
       −d        Delete one or more files from archive.
       −i        Position new files in the archive before the file in the
                 archive named by the posname operand (equivalent to −b).
       −m        Move the named files in the archive. The −a, −b, or −i
                 options with the posname operand indicate the position;
                 otherwise, move the names files in the archive to the end
                 of the archive.
       −p        Write the contents of the files in the archive named by
                 file operands from archive to the standard output. If no
                 file operands are specified, the contents of all files in
                 the archive shall be written in the order of the archive.
       −q        Append the named files to the end of the archive. In this
                 case ar does not check whether the added files are already
                 in the archive.  This is useful to bypass the searching
                 otherwise done when creating a large archive piece by
                 piece.
       −r        Replace or add files to archive.  If the archive named by
                 archive does not exist, a new archive shall be created and
                 a diagnostic message shall be written to standard error
                 (unless the −c option is specified). If no files are
                 specified and the archive exists, the results are
                 undefined. Files that replace existing files in the archive
                 shall not change the order of the archive. Files that do
                 not replace existing files in the archive shall be appended
                 to the archive unless a −a, −b, or −i option specifies
                 another position.
       −s        Force the regeneration of the archive symbol table even if
                 ar is not invoked with an option that modifies the archive
                 contents. This option is useful to restore the archive
                 symbol table after it has been stripped; see strip.
       −t        Write a table of contents of archive to the standard
                 output. Only the files specified by the file operands shall
                 be included in the written list. If no file operands are
                 specified, all files in archive shall be included in the
                 order of the archive.
       −T        Allow filename truncation of extracted files whose archive
                 names are longer than the file system can support. By
                 default, extracting a file with a name that is too long
                 shall be an error; a diagnostic message shall be written
                 and the file shall not be extracted.
       −u        Update older files in the archive. When used with the −r
                 option, files in the archive shall be replaced only if the
                 corresponding file has a modification time that is at least
                 as new as the modification time of the file in the archive.
       −v        Give verbose output. When used with the option characters
                 −d, −r, or −x, write a detailed file-by-file description of
                 the archive creation and maintenance activity, as described
                 in the STDOUT section.
                 When used with −p, write the name of the file in the
                 archive to the standard output before writing the file in
                 the archive itself to the standard output, as described in
                 the STDOUT section.
                 When used with −t, include a long listing of information
                 about the files in the archive, as described in the STDOUT
                 section.
       −x        Extract the files in the archive named by the file operands
                 from archive.  The contents of the archive shall not be
                 changed. If no file operands are given, all files in the
                 archive shall be extracted. The modification time of each
                 file extracted shall be set to the time the file is
                 extracted from the archive.

OPERANDS         top

       The following operands shall be supported:
       archive   A pathname of the archive.
       file      A pathname. Only the last component shall be used when
                 comparing against the names of files in the archive. If two
                 or more file operands have the same last pathname component
                 (basename), the results are unspecified. The
                 implementation's archive format shall not truncate valid
                 filenames of files added to or replaced in the archive.
       posname   The name of a file in the archive, used for relative
                 positioning; see options −m and −r.

STDIN         top

       Not used.

INPUT FILES         top

       The archive named by archive shall be a file in the format created by
       ar −r.

ENVIRONMENT VARIABLES         top

       The following environment variables shall affect the execution of ar:
       LANG      Provide a default value for the internationalization
                 variables that are unset or null. (See the Base Definitions
                 volume of POSIX.1‐2008, Section 8.2, Internationalization
                 Variables for the precedence of internationalization
                 variables used to determine the values of locale
                 categories.)
       LC_ALL    If set to a non-empty string value, override the values of
                 all the other internationalization variables.
       LC_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).
       LC_MESSAGES
                 Determine the locale that should be used to affect the
                 format and contents of diagnostic messages written to
                 standard error.
       LC_TIME   Determine the format and content for date and time strings
                 written by ar −tv.
       NLSPATH   Determine the location of message catalogs for the
                 processing of LC_MESSAGES.
       TMPDIR    Determine the pathname that overrides the default directory
                 for temporary files, if any.
       TZ        Determine the timezone used to calculate date and time
                 strings written by ar −tv.  If TZ is unset or null, an
                 unspecified default timezone shall be used.

ASYNCHRONOUS EVENTS         top

       Default.

STDOUT         top

       If the −d option is used with the −v option, the standard output
       format shall be:
           "d − %s\n", <file>
       where file is the operand specified on the command line.
       If the −p option is used with the −v option, ar shall precede the
       contents of each file with:
           "\n<%s>\n\n", <file>
       where file is the operand specified on the command line, if file
       operands were specified, and the name of the file in the archive if
       they were not.
       If the −r option is used with the −v option:
        *  If file is already in the archive, the standard output format
           shall be:
               "r − %s\n", <file>
           where <file> is the operand specified on the command line.
        *  If file is not already in the archive, the standard output format
           shall be:
               "a − %s\n", <file>
           where <file> is the operand specified on the command line.
       If the −t option is used, ar shall write the names of the files in
       the archive to the standard output in the format:
           "%s\n", <file>
       where file is the operand specified on the command line, if file
       operands were specified, or the name of the file in the archive if
       they were not.
       If the −t option is used with the −v option, the standard output
       format shall be:
           "%s %u/%u %u %s %d %d:%d %d %s\n", <member mode>, <user ID>,
               <group ID>, <number of bytes in member>,
               <abbreviated month>, <day-of-month>, <hour>,
               <minute>, <year>, <file>
       where:
       <file>    Shall be the operand specified on the command line, if file
                 operands were specified, or the name of the file in the
                 archive if they were not.
       <member mode>
                 Shall be formatted the same as the <file mode> string
                 defined in the STDOUT section of ls, except that the first
                 character, the <entry type>, is not used; the string
                 represents the file mode of the file in the archive at the
                 time it was added to or replaced in the archive.
       The following represent the last-modification time of a file when it
       was most recently added to or replaced in the archive:
       <abbreviated month>
                 Equivalent to the format of the %b conversion specification
                 format in date.
       <day-of-month>
                 Equivalent to the format of the %e conversion specification
                 format in date.
       <hour>    Equivalent to the format of the %H conversion specification
                 format in date.
       <minute>  Equivalent to the format of the %M conversion specification
                 format in date.
       <year>    Equivalent to the format of the %Y conversion specification
                 format in date.
       When LC_TIME does not specify the POSIX locale, a different format
       and order of presentation of these fields relative to each other may
       be used in a format appropriate in the specified locale.
       If the −x option is used with the −v option, the standard output
       format shall be:
           "x − %s\n", <file>
       where file is the operand specified on the command line, if file
       operands were specified, or the name of the file in the archive if
       they were not.

STDERR         top

       The standard error shall be used only for diagnostic messages.  The
       diagnostic message about creating a new archive when −c is not
       specified shall not modify the exit status.

OUTPUT FILES         top

       Archives are files with unspecified formats.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       The following exit values shall be returned:
        0    Successful completion.
       >0    An error occurred.

CONSEQUENCES OF ERRORS         top

       Default.
       The following sections are informative.

APPLICATION USAGE         top

       None.

EXAMPLES         top

       None.

RATIONALE         top

       The archive format is not described. It is recognized that there are
       several known ar formats, which are not compatible. The ar utility is
       included, however, to allow creation of archives that are intended
       for use only on one machine. The archive is specified as a file, and
       it can be moved as a file. This does allow an archive to be moved
       from one machine to another machine that uses the same implementation
       of ar.
       Utilities such as pax (and its forebears tar and cpio) also provide
       portable ``archives''. This is a not a duplication; the ar utility is
       included to provide an interface primarily for make and the
       compilers, based on a historical model.
       In historical implementations, the −q option (available on XSI-
       conforming systems) is known to execute quickly because ar does not
       check on whether the added members are already in the archive. This
       is useful to bypass the searching otherwise done when creating a
       large archive piece-by-piece. These remarks may but need not remain
       true for a brand new implementation of this utility; hence, these
       remarks have been moved into the RATIONALE.
       BSD implementations historically required applications to provide the
       −s option whenever the archive was supposed to contain a symbol
       table.  As in this volume of POSIX.1‐2008, System V historically
       creates or updates an archive symbol table whenever an object file is
       removed from, added to, or updated in the archive.
       The OPERANDS section requires what might seem to be true without
       specifying it: the archive cannot truncate the filenames below
       {NAME_MAX}.  Some historical implementations do so, however, causing
       unexpected results for the application. Therefore, this volume of
       POSIX.1‐2008 makes the requirement explicit to avoid
       misunderstandings.
       According to the System V documentation, the options −dmpqrtx are not
       required to begin with a <hyphen> ('−').  This volume of POSIX.1‐2008
       requires that a conforming application use the leading <hyphen>.
       The archive format used by the 4.4 BSD implementation is documented
       in this RATIONALE as an example:
              A file created by ar begins with the ``magic'' string
              "!<arch>\n".  The rest of the archive is made up of objects,
              each of which is composed of a header for a file, a possible
              filename, and the file contents. The header is portable
              between machine architectures, and, if the file contents are
              printable, the archive is itself printable.
              The header is made up of six ASCII fields, followed by a two-
              character trailer. The fields are the object name (16
              characters), the file last modification time (12 characters),
              the user and group IDs (each 6 characters), the file mode (8
              characters), and the file size (10 characters). All numeric
              fields are in decimal, except for the file mode, which is in
              octal.
              The modification time is the file st_mtime field. The user and
              group IDs are the file st_uid and st_gid fields. The file mode
              is the file st_mode field. The file size is the file st_size
              field. The two-byte trailer is the string "`<newline>".
              Only the name field has any provision for overflow. If any
              filename is more than 16 characters in length or contains an
              embedded space, the string "#1/" followed by the ASCII length
              of the name is written in the name field.  The file size
              (stored in the archive header) is incremented by the length of
              the name. The name is then written immediately following the
              archive header.
              Any unused characters in any of these fields are written as
              <space> characters. If any fields are their particular maximum
              number of characters in length, there is no separation between
              the fields.
              Objects in the archive are always an even number of bytes
              long; files that are an odd number of bytes long are padded
              with a <newline>, although the size in the header does not
              reflect this.
       The ar utility description requires that (when all its members are
       valid object files) ar produce an object code library, which the
       linkage editor can use to extract object modules. If the linkage
       editor needs a symbol table to permit random access to the archive,
       ar must provide it; however, ar does not require a symbol table.
       The BSD −o option was omitted. It is a rare conforming application
       that uses ar to extract object code from a library with concern for
       its modification time, since this can only be of importance to make.
       Hence, since this functionality is not deemed important for
       applications portability, the modification time of the extracted
       files is set to the current time.
       There is at least one known implementation (for a small computer)
       that can accommodate only object files for that system, disallowing
       mixed object and other files. The ability to handle any type of file
       is not only historical practice for most implementations, but is also
       a reasonable expectation.
       Consideration was given to changing the output format of ar −tv to
       the same format as the output of ls −l.  This would have made parsing
       the output of ar the same as that of ls.  This was rejected in part
       because the current ar format is commonly used and changes would
       break historical usage.  Second, ar gives the user ID and group ID in
       numeric format separated by a <slash>.  Changing this to be the user
       name and group name would not be correct if the archive were moved to
       a machine that contained a different user database. Since ar cannot
       know whether the archive was generated on the same machine, it cannot
       tell what to report.
       The text on the −ur option combination is historical practice—since
       one filename can easily represent two different files (for example,
       /a/foo and /b/foo), it is reasonable to replace the file in the
       archive even when the modification time in the archive is identical
       to that in the file system.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       c99(1p), date(1p), fort77(1p), pax(1p), strip(1p)
       The Base Definitions volume of POSIX.1‐2008, Chapter 8, Environment
       Variables, Section 12.2, Utility Syntax Guidelines, unistd.h(0p),
       description of {POSIX_NO_TRUNC}

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The Open
       Group Base Specifications Issue 7, Copyright (C) 2013 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
       applied.) 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.unix.org/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                 2013                              AR(1P)

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