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+This is tar.info, produced by makeinfo version 4.8 from tar.texi.
+
+   This manual is for GNU `tar' (version 1.17, 8 June 2007), which
+creates and extracts files from archives.
+
+   Copyright (C) 1992, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 2003,
+2004, 2005, 2006, 2007 Free Software Foundation, Inc.
+
+     Permission is granted to copy, distribute and/or modify this
+     document under the terms of the GNU Free Documentation License,
+     Version 1.1 or any later version published by the Free Software
+     Foundation; with no Invariant Sections, with the Front-Cover Texts
+     being "A GNU Manual," and with the Back-Cover Texts as in (a)
+     below.  A copy of the license is included in the section entitled
+     "GNU Free Documentation License".
+
+     (a) The FSF's Back-Cover Text is: "You are free to copy and modify
+     this GNU Manual.  Buying copies from GNU Press supports the FSF in
+     developing GNU and promoting software freedom."
+
+INFO-DIR-SECTION Archiving
+START-INFO-DIR-ENTRY
+* Tar: (tar).                   Making tape (or disk) archives.
+END-INFO-DIR-ENTRY
+
+INFO-DIR-SECTION Individual utilities
+START-INFO-DIR-ENTRY
+* tar: (tar)tar invocation.                     Invoking GNU `tar'.
+END-INFO-DIR-ENTRY
+
+
+File: tar.info,  Node: Portability,  Next: cpio,  Prev: Attributes,  Up: Formats
+
+8.3 Making `tar' Archives More Portable
+=======================================
+
+Creating a `tar' archive on a particular system that is meant to be
+useful later on many other machines and with other versions of `tar' is
+more challenging than you might think.  `tar' archive formats have been
+evolving since the first versions of Unix.  Many such formats are
+around, and are not always compatible with each other.  This section
+discusses a few problems, and gives some advice about making `tar'
+archives more portable.
+
+   One golden rule is simplicity.  For example, limit your `tar'
+archives to contain only regular files and directories, avoiding other
+kind of special files.  Do not attempt to save sparse files or
+contiguous files as such.  Let's discuss a few more problems, in turn.
+
+* Menu:
+
+* Portable Names::              Portable Names
+* dereference::                 Symbolic Links
+* old::                         Old V7 Archives
+* ustar::                       Ustar Archives
+* gnu::                         GNU and old GNU format archives.
+* posix::                       POSIX archives
+* Checksumming::                Checksumming Problems
+* Large or Negative Values::    Large files, negative time stamps, etc.
+* Other Tars::                  How to Extract GNU-Specific Data Using
+                                Other `tar' Implementations
+
+
+File: tar.info,  Node: Portable Names,  Next: dereference,  Up: Portability
+
+8.3.1 Portable Names
+--------------------
+
+Use portable file and member names.  A name is portable if it contains
+only ASCII letters and digits, `/', `.', `_', and `-'; it cannot be
+empty, start with `-' or `//', or contain `/-'.  Avoid deep directory
+nesting.  For portability to old Unix hosts, limit your file name
+components to 14 characters or less.
+
+   If you intend to have your `tar' archives to be read under MSDOS,
+you should not rely on case distinction for file names, and you might
+use the GNU `doschk' program for helping you further diagnosing illegal
+MSDOS names, which are even more limited than System V's.
+
+
+File: tar.info,  Node: dereference,  Next: old,  Prev: Portable Names,  Up: Portability
+
+8.3.2 Symbolic Links
+--------------------
+
+Normally, when `tar' archives a symbolic link, it writes a block to the
+archive naming the target of the link.  In that way, the `tar' archive
+is a faithful record of the file system contents.  `--dereference'
+(`-h') is used with `--create' (`-c'), and causes `tar' to archive the
+files symbolic links point to, instead of the links themselves.  When
+this option is used, when `tar' encounters a symbolic link, it will
+archive the linked-to file, instead of simply recording the presence of
+a symbolic link.
+
+   The name under which the file is stored in the file system is not
+recorded in the archive.  To record both the symbolic link name and the
+file name in the system, archive the file under both names.  If all
+links were recorded automatically by `tar', an extracted file might be
+linked to a file name that no longer exists in the file system.
+
+   If a linked-to file is encountered again by `tar' while creating the
+same archive, an entire second copy of it will be stored.  (This
+_might_ be considered a bug.)
+
+   So, for portable archives, do not archive symbolic links as such,
+and use `--dereference' (`-h'): many systems do not support symbolic
+links, and moreover, your distribution might be unusable if it contains
+unresolved symbolic links.
+
+
+File: tar.info,  Node: old,  Next: ustar,  Prev: dereference,  Up: Portability
+
+8.3.3 Old V7 Archives
+---------------------
+
+Certain old versions of `tar' cannot handle additional information
+recorded by newer `tar' programs.  To create an archive in V7 format
+(not ANSI), which can be read by these old versions, specify the
+`--format=v7' option in conjunction with the `--create' (`-c') (`tar'
+also accepts `--portability' or `--old-archive' for this option).  When
+you specify it, `tar' leaves out information about directories, pipes,
+fifos, contiguous files, and device files, and specifies file ownership
+by group and user IDs instead of group and user names.
+
+   When updating an archive, do not use `--format=v7' unless the
+archive was created using this option.
+
+   In most cases, a _new_ format archive can be read by an _old_ `tar'
+program without serious trouble, so this option should seldom be
+needed.  On the other hand, most modern `tar's are able to read old
+format archives, so it might be safer for you to always use
+`--format=v7' for your distributions.  Notice, however, that `ustar'
+format is a better alternative, as it is free from many of `v7''s
+drawbacks.
+
+
+File: tar.info,  Node: ustar,  Next: gnu,  Prev: old,  Up: Portability
+
+8.3.4 Ustar Archive Format
+--------------------------
+
+Archive format defined by POSIX.1-1988 specification is called `ustar'.
+Although it is more flexible than the V7 format, it still has many
+restrictions (*Note ustar: Formats, for the detailed description of
+`ustar' format).  Along with V7 format, `ustar' format is a good choice
+for archives intended to be read with other implementations of `tar'.
+
+   To create archive in `ustar' format, use `--format=ustar' option in
+conjunction with the `--create' (`-c').
+
+
+File: tar.info,  Node: gnu,  Next: posix,  Prev: ustar,  Up: Portability
+
+8.3.5 GNU and old GNU `tar' format
+----------------------------------
+
+GNU `tar' was based on an early draft of the POSIX 1003.1 `ustar'
+standard.  GNU extensions to `tar', such as the support for file names
+longer than 100 characters, use portions of the `tar' header record
+which were specified in that POSIX draft as unused.  Subsequent changes
+in POSIX have allocated the same parts of the header record for other
+purposes.  As a result, GNU `tar' format is incompatible with the
+current POSIX specification, and with `tar' programs that follow it.
+
+   In the majority of cases, `tar' will be configured to create this
+format by default.  This will change in future releases, since we plan
+to make `POSIX' format the default.
+
+   To force creation a GNU `tar' archive, use option `--format=gnu'.
+
+
+File: tar.info,  Node: posix,  Next: Checksumming,  Prev: gnu,  Up: Portability
+
+8.3.6 GNU `tar' and POSIX `tar'
+-------------------------------
+
+Starting from version 1.14 GNU `tar' features full support for
+POSIX.1-2001 archives.
+
+   A POSIX conformant archive will be created if `tar' was given
+`--format=posix' (`--format=pax') option.  No special option is
+required to read and extract from a POSIX archive.
+
+* Menu:
+
+* PAX keywords:: Controlling Extended Header Keywords.
+
+
+File: tar.info,  Node: PAX keywords,  Up: posix
+
+8.3.6.1 Controlling Extended Header Keywords
+............................................
+
+`--pax-option=KEYWORD-LIST'
+     Handle keywords in PAX extended headers.  This option is
+     equivalent to `-o' option of the `pax' utility.
+
+   KEYWORD-LIST is a comma-separated list of keyword options, each
+keyword option taking one of the following forms:
+
+`delete=PATTERN'
+     When used with one of archive-creation commands, this option
+     instructs `tar' to omit from extended header records that it
+     produces any keywords matching the string PATTERN.
+
+     When used in extract or list mode, this option instructs tar to
+     ignore any keywords matching the given PATTERN in the extended
+     header records.  In both cases, matching is performed using the
+     pattern matching notation described in POSIX 1003.2, 3.13 (*note
+     wildcards::).  For example:
+
+          --pax-option delete=security.*
+
+     would suppress security-related information.
+
+`exthdr.name=STRING'
+     This keyword allows user control over the name that is written
+     into the ustar header blocks for the extended headers.  The name
+     is obtained from STRING after making the following substitutions:
+
+     Meta-character    Replaced By
+     -------------------------------------------------------- 
+     %d                The directory name of the file,
+                       equivalent to the result of the
+                       `dirname' utility on the translated
+                       file name.
+     %f                The name of the file with the
+                       directory information stripped,
+                       equivalent to the result of the
+                       `basename' utility on the translated
+                       file name.
+     %p                The process ID of the `tar' process.
+     %%                A `%' character.
+
+     Any other `%' characters in STRING produce undefined results.
+
+     If no option `exthdr.name=string' is specified, `tar' will use the
+     following default value:
+
+          %d/PaxHeaders.%p/%f
+
+`globexthdr.name=STRING'
+     This keyword allows user control over the name that is written into
+     the ustar header blocks for global extended header records.  The
+     name is obtained from the contents of STRING, after making the
+     following substitutions:
+
+     Meta-character    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 `tar' process.
+     %%                A `%' character.
+
+     Any other `%' characters in STRING produce undefined results.
+
+     If no option `globexthdr.name=string' is specified, `tar' will use
+     the following default value:
+
+          $TMPDIR/GlobalHead.%p.%n
+
+     where `$TMPDIR' represents the value of the TMPDIR environment
+     variable.  If TMPDIR is not set, `tar' uses `/tmp'.
+
+`KEYWORD=VALUE'
+     When used with one of archive-creation commands, these
+     keyword/value pairs will be included at the beginning of the
+     archive in a global extended header record.  When used with one of
+     archive-reading commands, `tar' will behave as if it has
+     encountered these keyword/value pairs at the beginning of the
+     archive in a global extended header record.
+
+`KEYWORD:=VALUE'
+     When used with one of archive-creation commands, these
+     keyword/value pairs will be included as records at the beginning
+     of an extended header for each file.  This is effectively
+     equivalent to KEYWORD=VALUE form except that it creates no global
+     extended header records.
+
+     When used with one of archive-reading commands, `tar' will behave
+     as if these keyword/value pairs were included as records at the
+     end of each extended header; thus, they will override any global or
+     file-specific extended header record keywords of the same names.
+     For example, in the command:
+
+          tar --format=posix --create \
+              --file archive --pax-option gname:=user .
+
+     the group name will be forced to a new value for all files stored
+     in the archive.
+
+
+File: tar.info,  Node: Checksumming,  Next: Large or Negative Values,  Prev: posix,  Up: Portability
+
+8.3.7 Checksumming Problems
+---------------------------
+
+SunOS and HP-UX `tar' fail to accept archives created using GNU `tar'
+and containing non-ASCII file names, that is, file names having
+characters with the eight bit set, because they use signed checksums,
+while GNU `tar' uses unsigned checksums while creating archives, as per
+POSIX standards.  On reading, GNU `tar' computes both checksums and
+accept any.  It is somewhat worrying that a lot of people may go around
+doing backup of their files using faulty (or at least non-standard)
+software, not learning about it until it's time to restore their
+missing files with an incompatible file extractor, or vice versa.
+
+   GNU `tar' compute checksums both ways, and accept any on read, so
+GNU tar can read Sun tapes even with their wrong checksums.  GNU `tar'
+produces the standard checksum, however, raising incompatibilities with
+Sun.  That is to say, GNU `tar' has not been modified to _produce_
+incorrect archives to be read by buggy `tar''s.  I've been told that
+more recent Sun `tar' now read standard archives, so maybe Sun did a
+similar patch, after all?
+
+   The story seems to be that when Sun first imported `tar' sources on
+their system, they recompiled it without realizing that the checksums
+were computed differently, because of a change in the default signing
+of `char''s in their compiler.  So they started computing checksums
+wrongly.  When they later realized their mistake, they merely decided
+to stay compatible with it, and with themselves afterwards.
+Presumably, but I do not really know, HP-UX has chosen that their `tar'
+archives to be compatible with Sun's.  The current standards do not
+favor Sun `tar' format.  In any case, it now falls on the shoulders of
+SunOS and HP-UX users to get a `tar' able to read the good archives
+they receive.
+
+
+File: tar.info,  Node: Large or Negative Values,  Next: Other Tars,  Prev: Checksumming,  Up: Portability
+
+8.3.8 Large or Negative Values
+------------------------------
+
+     _(This message will disappear, once this node revised.)_
+
+The above sections suggest to use `oldest possible' archive format if
+in doubt.  However, sometimes it is not possible.  If you attempt to
+archive a file whose metadata cannot be represented using required
+format, GNU `tar' will print error message and ignore such a file.  You
+will than have to switch to a format that is able to handle such
+values.  The format summary table (*note Formats::) will help you to do
+so.
+
+   In particular, when trying to archive files larger than 8GB or with
+timestamps not in the range 1970-01-01 00:00:00 through 2242-03-16
+12:56:31 UTC, you will have to chose between GNU and POSIX archive
+formats.  When considering which format to choose, bear in mind that
+the GNU format uses two's-complement base-256 notation to store values
+that do not fit into standard ustar range.  Such archives can generally
+be read only by a GNU `tar' implementation.  Moreover, they sometimes
+cannot be correctly restored on another hosts even by GNU `tar'.  For
+example, using two's complement representation for negative time stamps
+that assumes a signed 32-bit `time_t' generates archives that are not
+portable to hosts with differing `time_t' representations.
+
+   On the other hand, POSIX archives, generally speaking, can be
+extracted by any tar implementation that understands older ustar
+format.  The only exception are files larger than 8GB.
+
+
+File: tar.info,  Node: Other Tars,  Prev: Large or Negative Values,  Up: Portability
+
+8.3.9 How to Extract GNU-Specific Data Using Other `tar' Implementations
+------------------------------------------------------------------------
+
+In previous sections you became acquainted with various quirks
+necessary to make your archives portable.  Sometimes you may need to
+extract archives containing GNU-specific members using some third-party
+`tar' implementation or an older version of GNU `tar'.  Of course your
+best bet is to have GNU `tar' installed, but if it is for some reason
+impossible, this section will explain how to cope without it.
+
+   When we speak about "GNU-specific" members we mean two classes of
+them: members split between the volumes of a multi-volume archive and
+sparse members.  You will be able to always recover such members if the
+archive is in PAX format.  In addition split members can be recovered
+from archives in old GNU format.  The following subsections describe
+the required procedures in detail.
+
+* Menu:
+
+* Split Recovery::       Members Split Between Volumes
+* Sparse Recovery::      Sparse Members
+
+
+File: tar.info,  Node: Split Recovery,  Next: Sparse Recovery,  Up: Other Tars
+
+8.3.9.1 Extracting Members Split Between Volumes
+................................................
+
+If a member is split between several volumes of an old GNU format
+archive most third party `tar' implementation will fail to extract it.
+To extract it, use `tarcat' program (*note Tarcat::).  This program is
+available from GNU `tar' home page
+(http://www.gnu.org/software/tar/utils/tarcat.html).  It concatenates
+several archive volumes into a single valid archive.  For example, if
+you have three volumes named from `vol-1.tar' to `vol-3.tar', you can
+do the following to extract them using a third-party `tar':
+
+     $ tarcat vol-1.tar vol-2.tar vol-3.tar | tar xf -
+
+   You could use this approach for most (although not all) PAX format
+archives as well.  However, extracting split members from a PAX archive
+is a much easier task, because PAX volumes are constructed in such a
+way that each part of a split member is extracted to a different file
+by `tar' implementations that are not aware of GNU extensions.  More
+specifically, the very first part retains its original name, and all
+subsequent parts are named using the pattern:
+
+     %d/GNUFileParts.%p/%f.%n
+
+where symbols preceeded by `%' are "macro characters" that have the
+following meaning:
+
+Meta-character     Replaced By
+------------------------------------------------------------ 
+%d                 The directory name of the file,
+                   equivalent to the result of the
+                   `dirname' utility on its full name.
+%f                 The file name of the file, equivalent
+                   to the result of the `basename' utility
+                   on its full name.
+%p                 The process ID of the `tar' process that
+                   created the archive.
+%n                 Ordinal number of this particular part.
+
+   For example, if the file `var/longfile' was split during archive
+creation between three volumes, and the creator `tar' process had
+process ID `27962', then the member names will be:
+
+     var/longfile
+     var/GNUFileParts.27962/longfile.1
+     var/GNUFileParts.27962/longfile.2
+
+   When you extract your archive using a third-party `tar', these files
+will be created on your disk, and the only thing you will need to do to
+restore your file in its original form is concatenate them in the
+proper order, for example:
+
+     $ cd var
+     $ cat GNUFileParts.27962/longfile.1 \
+       GNUFileParts.27962/longfile.2 >> longfile
+     $ rm -f GNUFileParts.27962
+
+   Notice, that if the `tar' implementation you use supports PAX format
+archives, it will probably emit warnings about unknown keywords during
+extraction.  They will look like this:
+
+     Tar file too small
+     Unknown extended header keyword 'GNU.volume.filename' ignored.
+     Unknown extended header keyword 'GNU.volume.size' ignored.
+     Unknown extended header keyword 'GNU.volume.offset' ignored.
+
+You can safely ignore these warnings.
+
+   If your `tar' implementation is not PAX-aware, you will get more
+warnings and more files generated on your disk, e.g.:
+
+     $ tar xf vol-1.tar
+     var/PaxHeaders.27962/longfile: Unknown file type 'x', extracted as
+     normal file
+     Unexpected EOF in archive
+     $ tar xf vol-2.tar
+     tmp/GlobalHead.27962.1: Unknown file type 'g', extracted as normal file
+     GNUFileParts.27962/PaxHeaders.27962/sparsefile.1: Unknown file type
+     'x', extracted as normal file
+
+   Ignore these warnings.  The `PaxHeaders.*' directories created will
+contain files with "extended header keywords" describing the extracted
+files.  You can delete them, unless they describe sparse members.  Read
+further to learn more about them.
+
+
+File: tar.info,  Node: Sparse Recovery,  Prev: Split Recovery,  Up: Other Tars
+
+8.3.9.2 Extracting Sparse Members
+.................................
+
+Any `tar' implementation will be able to extract sparse members from a
+PAX archive.  However, the extracted files will be "condensed", i.e.,
+any zero blocks will be removed from them.  When we restore such a
+condensed file to its original form, by adding zero blocks (or "holes")
+back to their original locations, we call this process "expanding" a
+compressed sparse file.
+
+   To expand a file, you will need a simple auxiliary program called
+`xsparse'.  It is available in source form from GNU `tar' home page
+(http://www.gnu.org/software/tar/utils/xsparse.html).
+
+   Let's begin with archive members in "sparse format version 1.0"(1),
+which are the easiest to expand.  The condensed file will contain both
+file map and file data, so no additional data will be needed to restore
+it.  If the original file name was `DIR/NAME', then the condensed file
+will be named `DIR/GNUSparseFile.N/NAME', where N is a decimal
+number(2).
+
+   To expand a version 1.0 file, run `xsparse' as follows:
+
+     $ xsparse `cond-file'
+
+where `cond-file' is the name of the condensed file.  The utility will
+deduce the name for the resulting expanded file using the following
+algorithm:
+
+  1. If `cond-file' does not contain any directories, `../cond-file'
+     will be used;
+
+  2. If `cond-file' has the form `DIR/T/NAME', where both T and NAME
+     are simple names, with no `/' characters in them, the output file
+     name will be `DIR/NAME'.
+
+  3. Otherwise, if `cond-file' has the form `DIR/NAME', the output file
+     name will be `NAME'.
+
+   In the unlikely case when this algorithm does not suit your needs,
+you can explicitly specify output file name as a second argument to the
+command:
+
+     $ xsparse `cond-file' `out-file'
+
+   It is often a good idea to run `xsparse' in "dry run" mode first.
+In this mode, the command does not actually expand the file, but
+verbosely lists all actions it would be taking to do so.  The dry run
+mode is enabled by `-n' command line argument:
+
+     $ xsparse -n /home/gray/GNUSparseFile.6058/sparsefile
+     Reading v.1.0 sparse map
+     Expanding file `/home/gray/GNUSparseFile.6058/sparsefile' to
+     `/home/gray/sparsefile'
+     Finished dry run
+
+   To actually expand the file, you would run:
+
+     $ xsparse /home/gray/GNUSparseFile.6058/sparsefile
+
+The program behaves the same way all UNIX utilities do: it will keep
+quiet unless it has simething important to tell you (e.g. an error
+condition or something).  If you wish it to produce verbose output,
+similar to that from the dry run mode, use `-v' option:
+
+     $ xsparse -v /home/gray/GNUSparseFile.6058/sparsefile
+     Reading v.1.0 sparse map
+     Expanding file `/home/gray/GNUSparseFile.6058/sparsefile' to
+     `/home/gray/sparsefile'
+     Done
+
+   Additionally, if your `tar' implementation has extracted the
+"extended headers" for this file, you can instruct `xstar' to use them
+in order to verify the integrity of the expanded file.  The option `-x'
+sets the name of the extended header file to use.  Continuing our
+example:
+
+     $ xsparse -v -x /home/gray/PaxHeaders.6058/sparsefile \
+       /home/gray/GNUSparseFile.6058/sparsefile
+     Reading extended header file
+     Found variable GNU.sparse.major = 1
+     Found variable GNU.sparse.minor = 0
+     Found variable GNU.sparse.name = sparsefile
+     Found variable GNU.sparse.realsize = 217481216
+     Reading v.1.0 sparse map
+     Expanding file `/home/gray/GNUSparseFile.6058/sparsefile' to
+     `/home/gray/sparsefile'
+     Done
+
+   An "extended header" is a special `tar' archive header that precedes
+an archive member and contains a set of "variables", describing the
+member properties that cannot be stored in the standard `ustar' header.
+While optional for expanding sparse version 1.0 members, the use of
+extended headers is mandatory when expanding sparse members in older
+sparse formats: v.0.0 and v.0.1 (The sparse formats are described in
+detail in *note Sparse Formats::.)  So, for these formats, the question
+is: how to obtain extended headers from the archive?
+
+   If you use a `tar' implementation that does not support PAX format,
+extended headers for each member will be extracted as a separate file.
+If we represent the member name as `DIR/NAME', then the extended header
+file will be named `DIR/PaxHeaders.N/NAME', where N is an integer
+number.
+
+   Things become more difficult if your `tar' implementation does
+support PAX headers, because in this case you will have to manually
+extract the headers.  We recommend the following algorithm:
+
+  1. Consult the documentation of your `tar' implementation for an
+     option that prints "block numbers" along with the archive listing
+     (analogous to GNU `tar''s `-R' option).  For example, `star' has
+     `-block-number'.
+
+  2. Obtain verbose listing using the `block number' option, and find
+     block numbers of the sparse member in question and the member
+     immediately following it.  For example, running `star' on our
+     archive we obtain:
+
+          $ star -t -v -block-number -f arc.tar
+          ...
+          star: Unknown extended header keyword 'GNU.sparse.size' ignored.
+          star: Unknown extended header keyword 'GNU.sparse.numblocks' ignored.
+          star: Unknown extended header keyword 'GNU.sparse.name' ignored.
+          star: Unknown extended header keyword 'GNU.sparse.map' ignored.
+          block        56:  425984 -rw-r--r--  gray/users Jun 25 14:46 2006 GNUSparseFile.28124/sparsefile
+          block       897:   65391 -rw-r--r--  gray/users Jun 24 20:06 2006 README
+          ...
+
+     (as usual, ignore the warnings about unknown keywords.)
+
+  3. Let SIZE be the size of the sparse member, BS be its block number
+     and BN be the block number of the next member.  Compute:
+
+          N = BS - BN - SIZE/512 - 2
+
+     This number gives the size of the extended header part in tar
+     "blocks".  In our example, this formula gives: `897 - 56 - 425984
+     / 512 - 2 = 7'.
+
+  4. Use `dd' to extract the headers:
+
+          dd if=ARCHIVE of=HNAME bs=512 skip=BS count=N
+
+     where ARCHIVE is the archive name, HNAME is a name of the file to
+     store the extended header in, BS and N are computed in previous
+     steps.
+
+     In our example, this command will be
+
+          $ dd if=arc.tar of=xhdr bs=512 skip=56 count=7
+
+   Finally, you can expand the condensed file, using the obtained
+header:
+
+     $ xsparse -v -x xhdr GNUSparseFile.6058/sparsefile
+     Reading extended header file
+     Found variable GNU.sparse.size = 217481216
+     Found variable GNU.sparse.numblocks = 208
+     Found variable GNU.sparse.name = sparsefile
+     Found variable GNU.sparse.map = 0,2048,1050624,2048,...
+     Expanding file `GNUSparseFile.28124/sparsefile' to `sparsefile'
+     Done
+
+   ---------- Footnotes ----------
+
+   (1) *Note PAX 1::.
+
+   (2) technically speaking, N is a "process ID" of the `tar' process
+which created the archive (*note PAX keywords::).
+
+
+File: tar.info,  Node: cpio,  Prev: Portability,  Up: Formats
+
+8.4 Comparison of `tar' and `cpio'
+==================================
+
+     _(This message will disappear, once this node revised.)_
+
+The `cpio' archive formats, like `tar', do have maximum file name
+lengths.  The binary and old ASCII formats have a maximum file length
+of 256, and the new ASCII and CRC ASCII formats have a max file length
+of 1024.  GNU `cpio' can read and write archives with arbitrary file
+name lengths, but other `cpio' implementations may crash unexplainedly
+trying to read them.
+
+   `tar' handles symbolic links in the form in which it comes in BSD;
+`cpio' doesn't handle symbolic links in the form in which it comes in
+System V prior to SVR4, and some vendors may have added symlinks to
+their system without enhancing `cpio' to know about them.  Others may
+have enhanced it in a way other than the way I did it at Sun, and which
+was adopted by AT&T (and which is, I think, also present in the `cpio'
+that Berkeley picked up from AT&T and put into a later BSD release--I
+think I gave them my changes).
+
+   (SVR4 does some funny stuff with `tar'; basically, its `cpio' can
+handle `tar' format input, and write it on output, and it probably
+handles symbolic links.  They may not have bothered doing anything to
+enhance `tar' as a result.)
+
+   `cpio' handles special files; traditional `tar' doesn't.
+
+   `tar' comes with V7, System III, System V, and BSD source; `cpio'
+comes only with System III, System V, and later BSD (4.3-tahoe and
+later).
+
+   `tar''s way of handling multiple hard links to a file can handle
+file systems that support 32-bit inumbers (e.g., the BSD file system);
+`cpio's way requires you to play some games (in its "binary" format,
+i-numbers are only 16 bits, and in its "portable ASCII" format, they're
+18 bits--it would have to play games with the "file system ID" field of
+the header to make sure that the file system ID/i-number pairs of
+different files were always different), and I don't know which `cpio's,
+if any, play those games.  Those that don't might get confused and
+think two files are the same file when they're not, and make hard links
+between them.
+
+   `tar's way of handling multiple hard links to a file places only one
+copy of the link on the tape, but the name attached to that copy is the
+_only_ one you can use to retrieve the file; `cpio's way puts one copy
+for every link, but you can retrieve it using any of the names.
+
+     What type of check sum (if any) is used, and how is this
+     calculated.
+
+   See the attached manual pages for `tar' and `cpio' format.  `tar'
+uses a checksum which is the sum of all the bytes in the `tar' header
+for a file; `cpio' uses no checksum.
+
+     If anyone knows why `cpio' was made when `tar' was present at the
+     unix scene,
+
+   It wasn't.  `cpio' first showed up in PWB/UNIX 1.0; no
+generally-available version of UNIX had `tar' at the time.  I don't
+know whether any version that was generally available _within AT&T_ had
+`tar', or, if so, whether the people within AT&T who did `cpio' knew
+about it.
+
+   On restore, if there is a corruption on a tape `tar' will stop at
+that point, while `cpio' will skip over it and try to restore the rest
+of the files.
+
+   The main difference is just in the command syntax and header format.
+
+   `tar' is a little more tape-oriented in that everything is blocked
+to start on a record boundary.
+
+     Is there any differences between the ability to recover crashed
+     archives between the two of them.  (Is there any chance of
+     recovering crashed archives at all.)
+
+   Theoretically it should be easier under `tar' since the blocking
+lets you find a header with some variation of `dd skip=NN'.  However,
+modern `cpio''s and variations have an option to just search for the
+next file header after an error with a reasonable chance of resyncing.
+However, lots of tape driver software won't allow you to continue past
+a media error which should be the only reason for getting out of sync
+unless a file changed sizes while you were writing the archive.
+
+     If anyone knows why `cpio' was made when `tar' was present at the
+     unix scene, please tell me about this too.
+
+   Probably because it is more media efficient (by not blocking
+everything and using only the space needed for the headers where `tar'
+always uses 512 bytes per file header) and it knows how to archive
+special files.
+
+   You might want to look at the freely available alternatives.  The
+major ones are `afio', GNU `tar', and `pax', each of which have their
+own extensions with some backwards compatibility.
+
+   Sparse files were `tar'red as sparse files (which you can easily
+test, because the resulting archive gets smaller, and GNU `cpio' can no
+longer read it).
+
+
+File: tar.info,  Node: Media,  Next: Changes,  Prev: Formats,  Up: Top
+
+9 Tapes and Other Archive Media
+*******************************
+
+     _(This message will disappear, once this node revised.)_
+
+A few special cases about tape handling warrant more detailed
+description.  These special cases are discussed below.
+
+   Many complexities surround the use of `tar' on tape drives.  Since
+the creation and manipulation of archives located on magnetic tape was
+the original purpose of `tar', it contains many features making such
+manipulation easier.
+
+   Archives are usually written on dismountable media--tape cartridges,
+mag tapes, or floppy disks.
+
+   The amount of data a tape or disk holds depends not only on its size,
+but also on how it is formatted.  A 2400 foot long reel of mag tape
+holds 40 megabytes of data when formatted at 1600 bits per inch.  The
+physically smaller EXABYTE tape cartridge holds 2.3 gigabytes.
+
+   Magnetic media are re-usable--once the archive on a tape is no longer
+needed, the archive can be erased and the tape or disk used over.
+Media quality does deteriorate with use, however.  Most tapes or disks
+should be discarded when they begin to produce data errors.  EXABYTE
+tape cartridges should be discarded when they generate an "error count"
+(number of non-usable bits) of more than 10k.
+
+   Magnetic media are written and erased using magnetic fields, and
+should be protected from such fields to avoid damage to stored data.
+Sticking a floppy disk to a filing cabinet using a magnet is probably
+not a good idea.
+
+* Menu:
+
+* Device::                      Device selection and switching
+* Remote Tape Server::
+* Common Problems and Solutions::
+* Blocking::                    Blocking
+* Many::                        Many archives on one tape
+* Using Multiple Tapes::        Using Multiple Tapes
+* label::                       Including a Label in the Archive
+* verify::
+* Write Protection::
+
+
+File: tar.info,  Node: Device,  Next: Remote Tape Server,  Up: Media
+
+9.1 Device Selection and Switching
+==================================
+
+     _(This message will disappear, once this node revised.)_
+
+`-f [HOSTNAME:]FILE'
+`--file=[HOSTNAME:]FILE'
+     Use archive file or device FILE on HOSTNAME.
+
+   This option is used to specify the file name of the archive `tar'
+works on.
+
+   If the file name is `-', `tar' reads the archive from standard input
+(when listing or extracting), or writes it to standard output (when
+creating).  If the `-' file name is given when updating an archive,
+`tar' will read the original archive from its standard input, and will
+write the entire new archive to its standard output.
+
+   If the file name contains a `:', it is interpreted as `hostname:file
+name'.  If the HOSTNAME contains an "at" sign (`@'), it is treated as
+`user@hostname:file name'.  In either case, `tar' will invoke the
+command `rsh' (or `remsh') to start up an `/usr/libexec/rmt' on the
+remote machine.  If you give an alternate login name, it will be given
+to the `rsh'.  Naturally, the remote machine must have an executable
+`/usr/libexec/rmt'.  This program is free software from the University
+of California, and a copy of the source code can be found with the
+sources for `tar'; it's compiled and installed by default.  The exact
+path to this utility is determined when configuring the package.  It is
+`PREFIX/libexec/rmt', where PREFIX stands for your installation prefix.
+This location may also be overridden at runtime by using
+`rmt-command=COMMAND' option (*Note --rmt-command: Option Summary, for
+detailed description of this option.  *Note Remote Tape Server::, for
+the description of `rmt' command).
+
+   If this option is not given, but the environment variable `TAPE' is
+set, its value is used; otherwise, old versions of `tar' used a default
+archive name (which was picked when `tar' was compiled).  The default
+is normally set up to be the "first" tape drive or other transportable
+I/O medium on the system.
+
+   Starting with version 1.11.5, GNU `tar' uses standard input and
+standard output as the default device, and I will not try anymore
+supporting automatic device detection at installation time.  This was
+failing really in too many cases, it was hopeless.  This is now
+completely left to the installer to override standard input and
+standard output for default device, if this seems preferable.  Further,
+I think _most_ actual usages of `tar' are done with pipes or disks, not
+really tapes, cartridges or diskettes.
+
+   Some users think that using standard input and output is running
+after trouble.  This could lead to a nasty surprise on your screen if
+you forget to specify an output file name--especially if you are going
+through a network or terminal server capable of buffering large amounts
+of output.  We had so many bug reports in that area of configuring
+default tapes automatically, and so many contradicting requests, that
+we finally consider the problem to be portably intractable.  We could
+of course use something like `/dev/tape' as a default, but this is
+_also_ running after various kind of trouble, going from hung processes
+to accidental destruction of real tapes.  After having seen all this
+mess, using standard input and output as a default really sounds like
+the only clean choice left, and a very useful one too.
+
+   GNU `tar' reads and writes archive in records, I suspect this is the
+main reason why block devices are preferred over character devices.
+Most probably, block devices are more efficient too.  The installer
+could also check for `DEFTAPE' in `<sys/mtio.h>'.
+
+`--force-local'
+     Archive file is local even if it contains a colon.
+
+`--rsh-command=COMMAND'
+     Use remote COMMAND instead of `rsh'.  This option exists so that
+     people who use something other than the standard `rsh' (e.g., a
+     Kerberized `rsh') can access a remote device.
+
+     When this command is not used, the shell command found when the
+     `tar' program was installed is used instead.  This is the first
+     found of `/usr/ucb/rsh', `/usr/bin/remsh', `/usr/bin/rsh',
+     `/usr/bsd/rsh' or `/usr/bin/nsh'.  The installer may have
+     overridden this by defining the environment variable `RSH' _at
+     installation time_.
+
+`-[0-7][lmh]'
+     Specify drive and density.
+
+`-M'
+`--multi-volume'
+     Create/list/extract multi-volume archive.
+
+     This option causes `tar' to write a "multi-volume" archive--one
+     that may be larger than will fit on the medium used to hold it.
+     *Note Multi-Volume Archives::.
+
+`-L NUM'
+`--tape-length=NUM'
+     Change tape after writing NUM x 1024 bytes.
+
+     This option might be useful when your tape drivers do not properly
+     detect end of physical tapes.  By being slightly conservative on
+     the maximum tape length, you might avoid the problem entirely.
+
+`-F FILE'
+`--info-script=FILE'
+`--new-volume-script=FILE'
+     Execute `file' at end of each tape.  This implies `--multi-volume'
+     (`-M').  *Note info-script::, for a detailed description of this
+     option.
+
+
+File: tar.info,  Node: Remote Tape Server,  Next: Common Problems and Solutions,  Prev: Device,  Up: Media
+
+9.2 The Remote Tape Server
+==========================
+
+In order to access the tape drive on a remote machine, `tar' uses the
+remote tape server written at the University of California at Berkeley.
+The remote tape server must be installed as `PREFIX/libexec/rmt' on
+any machine whose tape drive you want to use.  `tar' calls `rmt' by
+running an `rsh' or `remsh' to the remote machine, optionally using a
+different login name if one is supplied.
+
+   A copy of the source for the remote tape server is provided.  It is
+Copyright (C) 1983 by the Regents of the University of California, but
+can be freely distributed.  It is compiled and installed by default.
+
+   Unless you use the `--absolute-names' (`-P') option, GNU `tar' will
+not allow you to create an archive that contains absolute file names (a
+file name beginning with `/'.) If you try, `tar' will automatically
+remove the leading `/' from the file names it stores in the archive.
+It will also type a warning message telling you what it is doing.
+
+   When reading an archive that was created with a different `tar'
+program, GNU `tar' automatically extracts entries in the archive which
+have absolute file names as if the file names were not absolute.  This
+is an important feature.  A visitor here once gave a `tar' tape to an
+operator to restore; the operator used Sun `tar' instead of GNU `tar',
+and the result was that it replaced large portions of our `/bin' and
+friends with versions from the tape; needless to say, we were unhappy
+about having to recover the file system from backup tapes.
+
+   For example, if the archive contained a file `/usr/bin/computoy',
+GNU `tar' would extract the file to `usr/bin/computoy', relative to the
+current directory.  If you want to extract the files in an archive to
+the same absolute names that they had when the archive was created, you
+should do a `cd /' before extracting the files from the archive, or you
+should either use the `--absolute-names' option, or use the command
+`tar -C / ...'.
+
+   Some versions of Unix (Ultrix 3.1 is known to have this problem),
+can claim that a short write near the end of a tape succeeded, when it
+actually failed.  This will result in the -M option not working
+correctly.  The best workaround at the moment is to use a significantly
+larger blocking factor than the default 20.
+
+   In order to update an archive, `tar' must be able to backspace the
+archive in order to reread or rewrite a record that was just read (or
+written).  This is currently possible only on two kinds of files: normal
+disk files (or any other file that can be backspaced with `lseek'), and
+industry-standard 9-track magnetic tape (or any other kind of tape that
+can be backspaced with the `MTIOCTOP' `ioctl'.
+
+   This means that the `--append', `--concatenate', and `--delete'
+commands will not work on any other kind of file.  Some media simply
+cannot be backspaced, which means these commands and options will never
+be able to work on them.  These non-backspacing media include pipes and
+cartridge tape drives.
+
+   Some other media can be backspaced, and `tar' will work on them once
+`tar' is modified to do so.
+
+   Archives created with the `--multi-volume', `--label', and
+`--incremental' (`-G') options may not be readable by other version of
+`tar'.  In particular, restoring a file that was split over a volume
+boundary will require some careful work with `dd', if it can be done at
+all.  Other versions of `tar' may also create an empty file whose name
+is that of the volume header.  Some versions of `tar' may create normal
+files instead of directories archived with the `--incremental' (`-G')
+option.
+
+
+File: tar.info,  Node: Common Problems and Solutions,  Next: Blocking,  Prev: Remote Tape Server,  Up: Media
+
+9.3 Some Common Problems and their Solutions
+============================================
+
+errors from system:
+permission denied
+no such file or directory
+not owner
+
+errors from `tar':
+directory checksum error
+header format error
+
+errors from media/system:
+i/o error
+device busy
+
+
+File: tar.info,  Node: Blocking,  Next: Many,  Prev: Common Problems and Solutions,  Up: Media
+
+9.4 Blocking
+============
+
+     _(This message will disappear, once this node revised.)_
+
+"Block" and "record" terminology is rather confused, and it is also
+confusing to the expert reader.  On the other hand, readers who are new
+to the field have a fresh mind, and they may safely skip the next two
+paragraphs, as the remainder of this manual uses those two terms in a
+quite consistent way.
+
+   John Gilmore, the writer of the public domain `tar' from which GNU
+`tar' was originally derived, wrote (June 1995):
+
+     The nomenclature of tape drives comes from IBM, where I believe
+     they were invented for the IBM 650 or so.  On IBM mainframes, what
+     is recorded on tape are tape blocks.  The logical organization of
+     data is into records.  There are various ways of putting records
+     into blocks, including `F' (fixed sized records), `V' (variable
+     sized records), `FB' (fixed blocked: fixed size records, N to a
+     block), `VB' (variable size records, N to a block), `VSB'
+     (variable spanned blocked: variable sized records that can occupy
+     more than one block), etc.  The `JCL' `DD RECFORM=' parameter
+     specified this to the operating system.
+
+     The Unix man page on `tar' was totally confused about this.  When
+     I wrote `PD TAR', I used the historically correct terminology
+     (`tar' writes data records, which are grouped into blocks).  It
+     appears that the bogus terminology made it into POSIX (no surprise
+     here), and now Franc,ois has migrated that terminology back into
+     the source code too.
+
+   The term "physical block" means the basic transfer chunk from or to
+a device, after which reading or writing may stop without anything
+being lost.  In this manual, the term "block" usually refers to a disk
+physical block, _assuming_ that each disk block is 512 bytes in length.
+It is true that some disk devices have different physical blocks, but
+`tar' ignore these differences in its own format, which is meant to be
+portable, so a `tar' block is always 512 bytes in length, and "block"
+always mean a `tar' block.  The term "logical block" often represents
+the basic chunk of allocation of many disk blocks as a single entity,
+which the operating system treats somewhat atomically; this concept is
+only barely used in GNU `tar'.
+
+   The term "physical record" is another way to speak of a physical
+block, those two terms are somewhat interchangeable.  In this manual,
+the term "record" usually refers to a tape physical block, _assuming_
+that the `tar' archive is kept on magnetic tape.  It is true that
+archives may be put on disk or used with pipes, but nevertheless, `tar'
+tries to read and write the archive one "record" at a time, whatever
+the medium in use.  One record is made up of an integral number of
+blocks, and this operation of putting many disk blocks into a single
+tape block is called "reblocking", or more simply, "blocking".  The
+term "logical record" refers to the logical organization of many
+characters into something meaningful to the application.  The term
+"unit record" describes a small set of characters which are transmitted
+whole to or by the application, and often refers to a line of text.
+Those two last terms are unrelated to what we call a "record" in GNU
+`tar'.
+
+   When writing to tapes, `tar' writes the contents of the archive in
+chunks known as "records".  To change the default blocking factor, use
+the `--blocking-factor=512-SIZE' (`-b 512-SIZE') option.  Each record
+will then be composed of 512-SIZE blocks.  (Each `tar' block is 512
+bytes.  *Note Standard::.)  Each file written to the archive uses at
+least one full record.  As a result, using a larger record size can
+result in more wasted space for small files.  On the other hand, a
+larger record size can often be read and written much more efficiently.
+
+   Further complicating the problem is that some tape drives ignore the
+blocking entirely.  For these, a larger record size can still improve
+performance (because the software layers above the tape drive still
+honor the blocking), but not as dramatically as on tape drives that
+honor blocking.
+
+   When reading an archive, `tar' can usually figure out the record
+size on itself.  When this is the case, and a non-standard record size
+was used when the archive was created, `tar' will print a message about
+a non-standard blocking factor, and then operate normally.  On some
+tape devices, however, `tar' cannot figure out the record size itself.
+On most of those, you can specify a blocking factor (with
+`--blocking-factor') larger than the actual blocking factor, and then
+use the `--read-full-records' (`-B') option.  (If you specify a
+blocking factor with `--blocking-factor' and don't use the
+`--read-full-records' option, then `tar' will not attempt to figure out
+the recording size itself.)  On some devices, you must always specify
+the record size exactly with `--blocking-factor' when reading, because
+`tar' cannot figure it out.  In any case, use `--list' (`-t') before
+doing any extractions to see whether `tar' is reading the archive
+correctly.
+
+   `tar' blocks are all fixed size (512 bytes), and its scheme for
+putting them into records is to put a whole number of them (one or
+more) into each record.  `tar' records are all the same size; at the
+end of the file there's a block containing all zeros, which is how you
+tell that the remainder of the last record(s) are garbage.
+
+   In a standard `tar' file (no options), the block size is 512 and the
+record size is 10240, for a blocking factor of 20.  What the
+`--blocking-factor' option does is sets the blocking factor, changing
+the record size while leaving the block size at 512 bytes.  20 was fine
+for ancient 800 or 1600 bpi reel-to-reel tape drives; most tape drives
+these days prefer much bigger records in order to stream and not waste
+tape.  When writing tapes for myself, some tend to use a factor of the
+order of 2048, say, giving a record size of around one megabyte.
+
+   If you use a blocking factor larger than 20, older `tar' programs
+might not be able to read the archive, so we recommend this as a limit
+to use in practice.  GNU `tar', however, will support arbitrarily large
+record sizes, limited only by the amount of virtual memory or the
+physical characteristics of the tape device.
+
+* Menu:
+
+* Format Variations::           Format Variations
+* Blocking Factor::             The Blocking Factor of an Archive
+
+
+File: tar.info,  Node: Format Variations,  Next: Blocking Factor,  Up: Blocking
+
+9.4.1 Format Variations
+-----------------------
+
+     _(This message will disappear, once this node revised.)_
+
+Format parameters specify how an archive is written on the archive
+media.  The best choice of format parameters will vary depending on the
+type and number of files being archived, and on the media used to store
+the archive.
+
+   To specify format parameters when accessing or creating an archive,
+you can use the options described in the following sections.  If you do
+not specify any format parameters, `tar' uses default parameters.  You
+cannot modify a compressed archive.  If you create an archive with the
+`--blocking-factor' option specified (*note Blocking Factor::), you
+must specify that blocking-factor when operating on the archive.  *Note
+Formats::, for other examples of format parameter considerations.
+
+
+File: tar.info,  Node: Blocking Factor,  Prev: Format Variations,  Up: Blocking
+
+9.4.2 The Blocking Factor of an Archive
+---------------------------------------
+
+     _(This message will disappear, once this node revised.)_
+
+The data in an archive is grouped into blocks, which are 512 bytes.
+Blocks are read and written in whole number multiples called "records".
+The number of blocks in a record (i.e., the size of a record in units
+of 512 bytes) is called the "blocking factor".  The
+`--blocking-factor=512-SIZE' (`-b 512-SIZE') option specifies the
+blocking factor of an archive.  The default blocking factor is
+typically 20 (i.e., 10240 bytes), but can be specified at installation.
+To find out the blocking factor of an existing archive, use `tar
+--list --file=ARCHIVE-NAME'.  This may not work on some devices.
+
+   Records are separated by gaps, which waste space on the archive
+media.  If you are archiving on magnetic tape, using a larger blocking
+factor (and therefore larger records) provides faster throughput and
+allows you to fit more data on a tape (because there are fewer gaps).
+If you are archiving on cartridge, a very large blocking factor (say
+126 or more) greatly increases performance.  A smaller blocking factor,
+on the other hand, may be useful when archiving small files, to avoid
+archiving lots of nulls as `tar' fills out the archive to the end of
+the record.  In general, the ideal record size depends on the size of
+the inter-record gaps on the tape you are using, and the average size
+of the files you are archiving.  *Note create::, for information on
+writing archives.
+
+   Archives with blocking factors larger than 20 cannot be read by very
+old versions of `tar', or by some newer versions of `tar' running on
+old machines with small address spaces.  With GNU `tar', the blocking
+factor of an archive is limited only by the maximum record size of the
+device containing the archive, or by the amount of available virtual
+memory.
+
+   Also, on some systems, not using adequate blocking factors, as
+sometimes imposed by the device drivers, may yield unexpected
+diagnostics.  For example, this has been reported:
+
+     Cannot write to /dev/dlt: Invalid argument
+
+In such cases, it sometimes happen that the `tar' bundled by the system
+is aware of block size idiosyncrasies, while GNU `tar' requires an
+explicit specification for the block size, which it cannot guess.  This
+yields some people to consider GNU `tar' is misbehaving, because by
+comparison, `the bundle `tar' works OK'.  Adding `-b 256', for example,
+might resolve the problem.
+
+   If you use a non-default blocking factor when you create an archive,
+you must specify the same blocking factor when you modify that archive.
+Some archive devices will also require you to specify the blocking
+factor when reading that archive, however this is not typically the
+case.  Usually, you can use `--list' (`-t') without specifying a
+blocking factor--`tar' reports a non-default record size and then lists
+the archive members as it would normally.  To extract files from an
+archive with a non-standard blocking factor (particularly if you're not
+sure what the blocking factor is), you can usually use the
+`--read-full-records' (`-B') option while specifying a blocking factor
+larger then the blocking factor of the archive (i.e., `tar --extract
+--read-full-records --blocking-factor=300'.  *Note list::, for more
+information on the `--list' (`-t') operation.  *Note Reading::, for a
+more detailed explanation of that option.
+
+`--blocking-factor=NUMBER'
+`-b NUMBER'
+     Specifies the blocking factor of an archive.  Can be used with any
+     operation, but is usually not necessary with `--list' (`-t').
+
+   Device blocking
+
+`-b BLOCKS'
+`--blocking-factor=BLOCKS'
+     Set record size to BLOCKS * 512 bytes.
+
+     This option is used to specify a "blocking factor" for the archive.
+     When reading or writing the archive, `tar', will do reads and
+     writes of the archive in records of BLOCK*512 bytes.  This is true
+     even when the archive is compressed.  Some devices requires that
+     all write operations be a multiple of a certain size, and so, `tar'
+     pads the archive out to the next record boundary.
+
+     The default blocking factor is set when `tar' is compiled, and is
+     typically 20.  Blocking factors larger than 20 cannot be read by
+     very old versions of `tar', or by some newer versions of `tar'
+     running on old machines with small address spaces.
+
+     With a magnetic tape, larger records give faster throughput and fit
+     more data on a tape (because there are fewer inter-record gaps).
+     If the archive is in a disk file or a pipe, you may want to specify
+     a smaller blocking factor, since a large one will result in a large
+     number of null bytes at the end of the archive.
+
+     When writing cartridge or other streaming tapes, a much larger
+     blocking factor (say 126 or more) will greatly increase
+     performance.  However, you must specify the same blocking factor
+     when reading or updating the archive.
+
+     Apparently, Exabyte drives have a physical block size of 8K bytes.
+     If we choose our blocksize as a multiple of 8k bytes, then the
+     problem seems to disappear.  Id est, we are using block size of
+     112 right now, and we haven't had the problem since we switched...
+
+     With GNU `tar' the blocking factor is limited only by the maximum
+     record size of the device containing the archive, or by the amount
+     of available virtual memory.
+
+     However, deblocking or reblocking is virtually avoided in a special
+     case which often occurs in practice, but which requires all the
+     following conditions to be simultaneously true:
+        * the archive is subject to a compression option,
+
+        * the archive is not handled through standard input or output,
+          nor redirected nor piped,
+
+        * the archive is directly handled to a local disk, instead of
+          any special device,
+
+        * `--blocking-factor' is not explicitly specified on the `tar'
+          invocation.
+
+     If the output goes directly to a local disk, and not through
+     stdout, then the last write is not extended to a full record size.
+     Otherwise, reblocking occurs.  Here are a few other remarks on this
+     topic:
+
+        * `gzip' will complain about trailing garbage if asked to
+          uncompress a compressed archive on tape, there is an option
+          to turn the message off, but it breaks the regularity of
+          simply having to use `PROG -d' for decompression.  It would
+          be nice if gzip was silently ignoring any number of trailing
+          zeros.  I'll ask Jean-loup Gailly, by sending a copy of this
+          message to him.
+
+        * `compress' does not show this problem, but as Jean-loup
+          pointed out to Michael, `compress -d' silently adds garbage
+          after the result of decompression, which tar ignores because
+          it already recognized its end-of-file indicator.  So this bug
+          may be safely ignored.
+
+        * `gzip -d -q' will be silent about the trailing zeros indeed,
+          but will still return an exit status of 2 which tar reports
+          in turn.  `tar' might ignore the exit status returned, but I
+          hate doing that, as it weakens the protection `tar' offers
+          users against other possible problems at decompression time.
+          If `gzip' was silently skipping trailing zeros _and_ also
+          avoiding setting the exit status in this innocuous case, that
+          would solve this situation.
+
+        * `tar' should become more solid at not stopping to read a pipe
+          at the first null block encountered.  This inelegantly breaks
+          the pipe.  `tar' should rather drain the pipe out before
+          exiting itself.
+
+`-i'
+`--ignore-zeros'
+     Ignore blocks of zeros in archive (means EOF).
+
+     The `--ignore-zeros' (`-i') option causes `tar' to ignore blocks
+     of zeros in the archive.  Normally a block of zeros indicates the
+     end of the archive, but when reading a damaged archive, or one
+     which was created by concatenating several archives together, this
+     option allows `tar' to read the entire archive.  This option is
+     not on by default because many versions of `tar' write garbage
+     after the zeroed blocks.
+
+     Note that this option causes `tar' to read to the end of the
+     archive file, which may sometimes avoid problems when multiple
+     files are stored on a single physical tape.
+
+`-B'
+`--read-full-records'
+     Reblock as we read (for reading 4.2BSD pipes).
+
+     If `--read-full-records' is used, `tar' will not panic if an
+     attempt to read a record from the archive does not return a full
+     record.  Instead, `tar' will keep reading until it has obtained a
+     full record.
+
+     This option is turned on by default when `tar' is reading an
+     archive from standard input, or from a remote machine.  This is
+     because on BSD Unix systems, a read of a pipe will return however
+     much happens to be in the pipe, even if it is less than `tar'
+     requested.  If this option was not used, `tar' would fail as soon
+     as it read an incomplete record from the pipe.
+
+     This option is also useful with the commands for updating an
+     archive.
+
+
+   Tape blocking
+
+   When handling various tapes or cartridges, you have to take care of
+selecting a proper blocking, that is, the number of disk blocks you put
+together as a single tape block on the tape, without intervening tape
+gaps.  A "tape gap" is a small landing area on the tape with no
+information on it, used for decelerating the tape to a full stop, and
+for later regaining the reading or writing speed.  When the tape driver
+starts reading a record, the record has to be read whole without
+stopping, as a tape gap is needed to stop the tape motion without
+loosing information.
+
+   Using higher blocking (putting more disk blocks per tape block) will
+use the tape more efficiently as there will be less tape gaps.  But
+reading such tapes may be more difficult for the system, as more memory
+will be required to receive at once the whole record.  Further, if
+there is a reading error on a huge record, this is less likely that the
+system will succeed in recovering the information.  So, blocking should
+not be too low, nor it should be too high.  `tar' uses by default a
+blocking of 20 for historical reasons, and it does not really matter
+when reading or writing to disk.  Current tape technology would easily
+accommodate higher blockings.  Sun recommends a blocking of 126 for
+Exabytes and 96 for DATs.  We were told that for some DLT drives, the
+blocking should be a multiple of 4Kb, preferably 64Kb (`-b 128') or 256
+for decent performance.  Other manufacturers may use different
+recommendations for the same tapes.  This might also depends of the
+buffering techniques used inside modern tape controllers.  Some imposes
+a minimum blocking, or a maximum blocking.  Others request blocking to
+be some exponent of two.
+
+   So, there is no fixed rule for blocking.  But blocking at read time
+should ideally be the same as blocking used at write time.  At one place
+I know, with a wide variety of equipment, they found it best to use a
+blocking of 32 to guarantee that their tapes are fully interchangeable.
+
+   I was also told that, for recycled tapes, prior erasure (by the same
+drive unit that will be used to create the archives) sometimes lowers
+the error rates observed at rewriting time.
+
+   I might also use `--number-blocks' instead of `--block-number', so
+`--block' will then expand to `--blocking-factor' unambiguously.
+
+
+File: tar.info,  Node: Many,  Next: Using Multiple Tapes,  Prev: Blocking,  Up: Media
+
+9.5 Many Archives on One Tape
+=============================
+
+Most tape devices have two entries in the `/dev' directory, or entries
+that come in pairs, which differ only in the minor number for this
+device.  Let's take for example `/dev/tape', which often points to the
+only or usual tape device of a given system.  There might be a
+corresponding `/dev/nrtape' or `/dev/ntape'.  The simpler name is the
+_rewinding_ version of the device, while the name having `nr' in it is
+the _no rewinding_ version of the same device.
+
+   A rewinding tape device will bring back the tape to its beginning
+point automatically when this device is opened or closed.  Since `tar'
+opens the archive file before using it and closes it afterwards, this
+means that a simple:
+
+     $ tar cf /dev/tape DIRECTORY
+
+will reposition the tape to its beginning both prior and after saving
+DIRECTORY contents to it, thus erasing prior tape contents and making
+it so that any subsequent write operation will destroy what has just
+been saved.
+
+   So, a rewinding device is normally meant to hold one and only one
+file.  If you want to put more than one `tar' archive on a given tape,
+you will need to avoid using the rewinding version of the tape device.
+You will also have to pay special attention to tape positioning.
+Errors in positioning may overwrite the valuable data already on your
+tape.  Many people, burnt by past experiences, will only use rewinding
+devices and limit themselves to one file per tape, precisely to avoid
+the risk of such errors.  Be fully aware that writing at the wrong
+position on a tape loses all information past this point and most
+probably until the end of the tape, and this destroyed information
+_cannot_ be recovered.
+
+   To save DIRECTORY-1 as a first archive at the beginning of a tape,
+and leave that tape ready for a second archive, you should use:
+
+     $ mt -f /dev/nrtape rewind
+     $ tar cf /dev/nrtape DIRECTORY-1
+
+   "Tape marks" are special magnetic patterns written on the tape
+media, which are later recognizable by the reading hardware.  These
+marks are used after each file, when there are many on a single tape.
+An empty file (that is to say, two tape marks in a row) signal the
+logical end of the tape, after which no file exist.  Usually,
+non-rewinding tape device drivers will react to the close request issued
+by `tar' by first writing two tape marks after your archive, and by
+backspacing over one of these.  So, if you remove the tape at that time
+from the tape drive, it is properly terminated.  But if you write
+another file at the current position, the second tape mark will be
+erased by the new information, leaving only one tape mark between files.
+
+   So, you may now save DIRECTORY-2 as a second archive after the first
+on the same tape by issuing the command:
+
+     $ tar cf /dev/nrtape DIRECTORY-2
+
+and so on for all the archives you want to put on the same tape.
+
+   Another usual case is that you do not write all the archives the same
+day, and you need to remove and store the tape between two archive
+sessions.  In general, you must remember how many files are already
+saved on your tape.  Suppose your tape already has 16 files on it, and
+that you are ready to write the 17th.  You have to take care of skipping
+the first 16 tape marks before saving DIRECTORY-17, say, by using these
+commands:
+
+     $ mt -f /dev/nrtape rewind
+     $ mt -f /dev/nrtape fsf 16
+     $ tar cf /dev/nrtape DIRECTORY-17
+
+   In all the previous examples, we put aside blocking considerations,
+but you should do the proper things for that as well.  *Note Blocking::.
+
+* Menu:
+
+* Tape Positioning::            Tape Positions and Tape Marks
+* mt::                          The `mt' Utility
+
+
+File: tar.info,  Node: Tape Positioning,  Next: mt,  Up: Many
+
+9.5.1 Tape Positions and Tape Marks
+-----------------------------------
+
+     _(This message will disappear, once this node revised.)_
+
+Just as archives can store more than one file from the file system,
+tapes can store more than one archive file.  To keep track of where
+archive files (or any other type of file stored on tape) begin and end,
+tape archive devices write magnetic "tape marks" on the archive media.
+Tape drives write one tape mark between files, two at the end of all
+the file entries.
+
+   If you think of data as a series of records "rrrr"'s, and tape marks
+as "*"'s, a tape might look like the following:
+
+     rrrr*rrrrrr*rrrrr*rr*rrrrr**-------------------------
+
+   Tape devices read and write tapes using a read/write "tape head"--a
+physical part of the device which can only access one point on the tape
+at a time.  When you use `tar' to read or write archive data from a
+tape device, the device will begin reading or writing from wherever on
+the tape the tape head happens to be, regardless of which archive or
+what part of the archive the tape head is on.  Before writing an
+archive, you should make sure that no data on the tape will be
+overwritten (unless it is no longer needed).  Before reading an
+archive, you should make sure the tape head is at the beginning of the
+archive you want to read.  You can do it manually via `mt' utility
+(*note mt::).  The `restore' script does that automatically (*note
+Scripted Restoration::).
+
+   If you want to add new archive file entries to a tape, you should
+advance the tape to the end of the existing file entries, backspace
+over the last tape mark, and write the new archive file.  If you were
+to add two archives to the example above, the tape might look like the
+following:
+
+     rrrr*rrrrrr*rrrrr*rr*rrrrr*rrr*rrrr**----------------
+
+
+File: tar.info,  Node: mt,  Prev: Tape Positioning,  Up: Many
+
+9.5.2 The `mt' Utility
+----------------------
+
+     _(This message will disappear, once this node revised.)_
+
+*Note Blocking Factor::.
+
+   You can use the `mt' utility to advance or rewind a tape past a
+specified number of archive files on the tape.  This will allow you to
+move to the beginning of an archive before extracting or reading it, or
+to the end of all the archives before writing a new one.
+
+   The syntax of the `mt' command is:
+
+     mt [-f TAPENAME] OPERATION [NUMBER]
+
+   where TAPENAME is the name of the tape device, NUMBER is the number
+of times an operation is performed (with a default of one), and
+OPERATION is one of the following:
+
+`eof'
+`weof'
+     Writes NUMBER tape marks at the current position on the tape.
+
+`fsf'
+     Moves tape position forward NUMBER files.
+
+`bsf'
+     Moves tape position back NUMBER files.
+
+`rewind'
+     Rewinds the tape.  (Ignores NUMBER).
+
+`offline'
+`rewoff1'
+     Rewinds the tape and takes the tape device off-line.  (Ignores
+     NUMBER).
+
+`status'
+     Prints status information about the tape unit.
+
+
+   If you don't specify a TAPENAME, `mt' uses the environment variable
+`TAPE'; if `TAPE' is not set, `mt' will use the default device
+specified in your `sys/mtio.h' file (`DEFTAPE' variable).  If this is
+not defined, the program will display a descriptive error message and
+exit with code 1.
+
+   `mt' returns a 0 exit status when the operation(s) were successful,
+1 if the command was unrecognized, and 2 if an operation failed.
+
+
+File: tar.info,  Node: Using Multiple Tapes,  Next: label,  Prev: Many,  Up: Media
+
+9.6 Using Multiple Tapes
+========================
+
+Often you might want to write a large archive, one larger than will fit
+on the actual tape you are using.  In such a case, you can run multiple
+`tar' commands, but this can be inconvenient, particularly if you are
+using options like `--exclude=PATTERN' or dumping entire file systems.
+Therefore, `tar' provides a special mode for creating multi-volume
+archives.
+
+   "Multi-volume" archive is a single `tar' archive, stored on several
+media volumes of fixed size.  Although in this section we will often
+call `volume' a "tape", there is absolutely no requirement for
+multi-volume archives to be stored on tapes.  Instead, they can use
+whatever media type the user finds convenient, they can even be located
+on files.
+
+   When creating a multi-volume archive, GNU `tar' continues to fill
+current volume until it runs out of space, then it switches to next
+volume (usually the operator is queried to replace the tape on this
+point), and continues working on the new volume.  This operation
+continues until all requested files are dumped.  If GNU `tar' detects
+end of media while dumping a file, such a file is archived in split
+form.  Some very big files can even be split across several volumes.
+
+   Each volume is itself a valid GNU `tar' archive, so it can be read
+without any special options.  Consequently any file member residing
+entirely on one volume can be extracted or otherwise operated upon
+without needing the other volume.  Sure enough, to extract a split
+member you would need all volumes its parts reside on.
+
+   Multi-volume archives suffer from several limitations.  In
+particular, they cannot be compressed.
+
+   GNU `tar' is able to create multi-volume archives of two formats
+(*note Formats::): `GNU' and `POSIX'.
+
+* Menu:
+
+* Multi-Volume Archives::       Archives Longer than One Tape or Disk
+* Tape Files::                  Tape Files
+* Tarcat::                      Concatenate Volumes into a Single Archive
+
+
+File: tar.info,  Node: Multi-Volume Archives,  Next: Tape Files,  Up: Using Multiple Tapes
+
+9.6.1 Archives Longer than One Tape or Disk
+-------------------------------------------
+
+To create an archive that is larger than will fit on a single unit of
+the media, use the `--multi-volume' (`-M') option in conjunction with
+the `--create' option (*note create::).  A "multi-volume" archive can
+be manipulated like any other archive (provided the `--multi-volume'
+option is specified), but is stored on more than one tape or disk.
+
+   When you specify `--multi-volume', `tar' does not report an error
+when it comes to the end of an archive volume (when reading), or the
+end of the media (when writing).  Instead, it prompts you to load a new
+storage volume.  If the archive is on a magnetic tape, you should
+change tapes when you see the prompt; if the archive is on a floppy
+disk, you should change disks; etc.
+
+`--multi-volume'
+`-M'
+     Creates a multi-volume archive, when used in conjunction with
+     `--create' (`-c').  To perform any other operation on a
+     multi-volume archive, specify `--multi-volume' in conjunction with
+     that operation.  For example:
+
+          $ tar --create --multi-volume --file=/dev/tape FILES
+
+   The method `tar' uses to detect end of tape is not perfect, and
+fails on some operating systems or on some devices.  If `tar' cannot
+detect the end of the tape itself, you can use `--tape-length' option
+to inform it about the capacity of the tape:
+
+`--tape-length=SIZE'
+`-L SIZE'
+     Set maximum length of a volume.  The SIZE argument should then be
+     the usable size of the tape in units of 1024 bytes.  This option
+     selects `--multi-volume' automatically.  For example:
+
+          $ tar --create --tape-length=41943040 --file=/dev/tape FILES
+
+   When GNU `tar' comes to the end of a storage media, it asks you to
+change the volume.  The built-in prompt for POSIX locale is(1):
+
+     Prepare volume #N for `ARCHIVE' and hit return:
+
+where N is the ordinal number of the volume to be created and ARCHIVE
+is archive file or device name.
+
+   When prompting for a new tape, `tar' accepts any of the following
+responses:
+
+`?'
+     Request `tar' to explain possible responses
+
+`q'
+     Request `tar' to exit immediately.
+
+`n FILE-NAME'
+     Request `tar' to write the next volume on the file FILE-NAME.
+
+`!'
+     Request `tar' to run a subshell.  This option can be disabled by
+     giving `--restrict' command line option to `tar'(2).
+
+`y'
+     Request `tar' to begin writing the next volume.
+
+   (You should only type `y' after you have changed the tape; otherwise
+`tar' will write over the volume it just finished.)
+
+   The volume number used by `tar' in its tape-changing prompt can be
+changed; if you give the `--volno-file=FILE-OF-NUMBER' option, then
+FILE-OF-NUMBER should be an non-existing file to be created, or else, a
+file already containing a decimal number.  That number will be used as
+the volume number of the first volume written.  When `tar' is finished,
+it will rewrite the file with the now-current volume number. (This does
+not change the volume number written on a tape label, as per *note
+label::, it _only_ affects the number used in the prompt.)
+
+   If you want more elaborate behavior than this, you can write a
+special "new volume script", that will be responsible for changing the
+volume, and instruct `tar' to use it instead of its normal prompting
+procedure:
+
+`--info-script=SCRIPT-NAME'
+`--new-volume-script=SCRIPT-NAME'
+`-F SCRIPT-NAME'
+     Specify the full name of the volume script to use.  The script can
+     be used to eject cassettes, or to broadcast messages such as
+     `Someone please come change my tape' when performing unattended
+     backups.
+
+   The SCRIPT-NAME is executed without any command line arguments.  It
+inherits `tar''s shell environment.  Additional data is passed to it
+via the following environment variables:
+
+`TAR_VERSION'
+     GNU `tar' version number.
+
+`TAR_ARCHIVE'
+     The name of the archive `tar' is processing.
+
+`TAR_VOLUME'
+     Ordinal number of the volume `tar' is about to start.
+
+`TAR_SUBCOMMAND'
+     Short option describing the operation `tar' is executing *Note
+     Operations::, for a complete list of subcommand options.
+
+`TAR_FORMAT'
+     Format of the archive being processed. *Note Formats::, for a
+     complete list of archive format names.
+
+`TAR_FD'
+     File descriptor which can be used to communicate the new volume
+     name to `tar'.
+
+   The volume script can instruct `tar' to use new archive name, by
+writing in to file descriptor `$TAR_FD' (see below for an example).
+
+   If the info script fails, `tar' exits; otherwise, it begins writing
+the next volume.
+
+   If you want `tar' to cycle through a series of files or tape drives,
+there are three approaches to choose from.  First of all, you can give
+`tar' multiple `--file' options.  In this case the specified files will
+be used, in sequence, as the successive volumes of the archive.  Only
+when the first one in the sequence needs to be used again will `tar'
+prompt for a tape change (or run the info script).  For example,
+suppose someone has two tape drives on a system named `/dev/tape0' and
+`/dev/tape1'.  For having GNU `tar' to switch to the second drive when
+it needs to write the second tape, and then back to the first tape,
+etc., just do either of:
+
+     $ tar --create --multi-volume --file=/dev/tape0 --file=/dev/tape1 FILES
+     $ tar cMff /dev/tape0 /dev/tape1 FILES
+
+   The second method is to use the `n' response to the tape-change
+prompt.
+
+   Finally, the most flexible approach is to use a volume script, that
+writes new archive name to the file descriptor `$TAR_FD'.  For example,
+the following volume script will create a series of archive files, named
+`ARCHIVE-VOL', where ARCHIVE is the name of the archive being created
+(as given by `--file' option) and VOL is the ordinal number of the
+archive being created:
+
+     #! /bin/sh
+     echo Preparing volume $TAR_VOLUME of $TAR_ARCHIVE.
+
+     name=`expr $TAR_ARCHIVE : '\(.*\)-.*'`
+     case $TAR_SUBCOMMAND in
+     -c)       ;;
+     -d|-x|-t) test -r ${name:-$TAR_ARCHIVE}-$TAR_VOLUME || exit 1
+     	  ;;
+     *)        exit 1
+     esac
+
+     echo ${name:-$TAR_ARCHIVE}-$TAR_VOLUME >&$TAR_FD
+
+   The same script cant be used while listing, comparing or extracting
+from the created archive.  For example:
+
+     # Create a multi-volume archive:
+     $ tar -c -L1024 -f archive.tar -F new-volume .
+     # Extract from the created archive:
+     $ tar -x -f archive.tar -F new-volume .
+
+Notice, that the first command had to use `-L' option, since otherwise
+GNU `tar' will end up writing everything to file `archive.tar'.
+
+   You can read each individual volume of a multi-volume archive as if
+it were an archive by itself.  For example, to list the contents of one
+volume, use `--list', without `--multi-volume' specified.  To extract
+an archive member from one volume (assuming it is described that
+volume), use `--extract', again without `--multi-volume'.
+
+   If an archive member is split across volumes (i.e., its entry begins
+on one volume of the media and ends on another), you need to specify
+`--multi-volume' to extract it successfully.  In this case, you should
+load the volume where the archive member starts, and use `tar --extract
+--multi-volume'--`tar' will prompt for later volumes as it needs them.
+*Note extracting archives::, for more information about extracting
+archives.
+
+   Multi-volume archives can be modified like any other archive.  To add
+files to a multi-volume archive, you need to only mount the last volume
+of the archive media (and new volumes, if needed).  For all other
+operations, you need to use the entire archive.
+
+   If a multi-volume archive was labeled using `--label=ARCHIVE-LABEL'
+(*note label::) when it was created, `tar' will not automatically label
+volumes which are added later.  To label subsequent volumes, specify
+`--label=ARCHIVE-LABEL' again in conjunction with the `--append',
+`--update' or `--concatenate' operation.
+
+   Notice that multi-volume support is a GNU extension and the archives
+created in this mode should be read only using GNU `tar'.  If you
+absolutely have to process such archives using a third-party `tar'
+implementation, read *note Split Recovery::.
+
+   ---------- Footnotes ----------
+
+   (1) If you run GNU `tar' under a different locale, the translation
+to the locale's language will be used.
+
+   (2) *Note --restrict::, for more information about this option
+
+
+File: tar.info,  Node: Tape Files,  Next: Tarcat,  Prev: Multi-Volume Archives,  Up: Using Multiple Tapes
+
+9.6.2 Tape Files
+----------------
+
+     _(This message will disappear, once this node revised.)_
+
+To give the archive a name which will be recorded in it, use the
+`--label=VOLUME-LABEL' (`-V VOLUME-LABEL') option.  This will write a
+special block identifying VOLUME-LABEL as the name of the archive to
+the front of the archive which will be displayed when the archive is
+listed with `--list'.  If you are creating a multi-volume archive with
+`--multi-volume' (*note Using Multiple Tapes::), then the volume label
+will have `Volume NNN' appended to the name you give, where NNN is the
+number of the volume of the archive.  (If you use the
+`--label=VOLUME-LABEL') option when reading an archive, it checks to
+make sure the label on the tape matches the one you give. *Note label::.
+
+   When `tar' writes an archive to tape, it creates a single tape file.
+If multiple archives are written to the same tape, one after the
+other, they each get written as separate tape files.  When extracting,
+it is necessary to position the tape at the right place before running
+`tar'.  To do this, use the `mt' command.  For more information on the
+`mt' command and on the organization of tapes into a sequence of tape
+files, see *note mt::.
+
+   People seem to often do:
+
+     --label="SOME-PREFIX `date +SOME-FORMAT`"
+
+   or such, for pushing a common date in all volumes or an archive set.
+
+
+File: tar.info,  Node: Tarcat,  Prev: Tape Files,  Up: Using Multiple Tapes
+
+9.6.3 Concatenate Volumes into a Single Archive
+-----------------------------------------------
+
+Sometimes it is necessary to convert existing GNU `tar' multi-volume
+archive to a single `tar' archive.  Simply concatenating all volumes
+into one will not work, since each volume carries an additional
+information at the beginning.  GNU `tar' is shipped with the shell
+script `tarcat' designed for this purpose.
+
+   The script takes a list of files comprising a multi-volume archive
+and creates the resulting archive at the standard output.  For example:
+
+     tarcat vol.1 vol.2 vol.3 | tar tf -
+
+   The script implements a simple heuristics to determine the format of
+the first volume file and to decide how to process the rest of the
+files.  However, it makes no attempt to verify whether the files are
+given in order or even if they are valid `tar' archives.  It uses `dd'
+and does not filter its standard error, so you will usually see lots of
+spurious messages.
+
+
+File: tar.info,  Node: label,  Next: verify,  Prev: Using Multiple Tapes,  Up: Media
+
+9.7 Including a Label in the Archive
+====================================
+
+     _(This message will disappear, once this node revised.)_
+
+To avoid problems caused by misplaced paper labels on the archive
+media, you can include a "label" entry--an archive member which
+contains the name of the archive--in the archive itself.  Use the
+`--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') option in conjunction with
+the `--create' operation to include a label entry in the archive as it
+is being created.
+
+`--label=ARCHIVE-LABEL'
+`-V ARCHIVE-LABEL'
+     Includes an "archive-label" at the beginning of the archive when
+     the archive is being created, when used in conjunction with the
+     `--create' operation.  Checks to make sure the archive label
+     matches the one specified (when used in conjunction with any other
+     operation.
+
+   If you create an archive using both `--label=ARCHIVE-LABEL' (`-V
+ARCHIVE-LABEL') and `--multi-volume' (`-M'), each volume of the archive
+will have an archive label of the form `ARCHIVE-LABEL Volume N', where
+N is 1 for the first volume, 2 for the next, and so on. *Note Using
+Multiple Tapes::, for information on creating multiple volume archives.
+
+   The volume label will be displayed by `--list' along with the file
+contents.  If verbose display is requested, it will also be explicitly
+marked as in the example below:
+
+     $ tar --verbose --list --file=iamanarchive
+     V--------- 0 0        0 1992-03-07 12:01 iamalabel--Volume Header--
+     -rw-r--r-- ringo user 40 1990-05-21 13:30 iamafilename
+
+   However, `--list' option will cause listing entire contents of the
+archive, which may be undesirable (for example, if the archive is
+stored on a tape).  You can request checking only the volume by
+specifying `--test-label' option.  This option reads only the first
+block of an archive, so it can be used with slow storage devices.  For
+example:
+
+     $ tar --test-label --file=iamanarchive
+     iamalabel
+
+   If `--test-label' is used with a single command line argument, `tar'
+compares the volume label with the argument.  It exits with code 0 if
+the two strings match, and with code 2 otherwise.  In this case no
+output is displayed.  For example:
+
+     $ tar --test-label --file=iamanarchive 'iamalable'
+     => 0
+     $ tar --test-label --file=iamanarchive 'iamalable' alabel
+     => 1
+
+   If you request any operation, other than `--create', along with
+using `--label' option, `tar' will first check if the archive label
+matches the one specified and will refuse to proceed if it does not.
+Use this as a safety precaution to avoid accidentally overwriting
+existing archives.  For example, if you wish to add files to `archive',
+presumably labeled with string `My volume', you will get:
+
+     $ tar -rf archive --label 'My volume' .
+     tar: Archive not labeled to match `My volume'
+
+in case its label does not match.  This will work even if `archive' is
+not labeled at all.
+
+   Similarly, `tar' will refuse to list or extract the archive if its
+label doesn't match the ARCHIVE-LABEL specified.  In those cases,
+ARCHIVE-LABEL argument is interpreted as a globbing-style pattern which
+must match the actual magnetic volume label.  *Note exclude::, for a
+precise description of how match is attempted(1).  If the switch
+`--multi-volume' (`-M') is being used, the volume label matcher will
+also suffix ARCHIVE-LABEL by ` Volume [1-9]*' if the initial match
+fails, before giving up.  Since the volume numbering is automatically
+added in labels at creation time, it sounded logical to equally help
+the user taking care of it when the archive is being read.
+
+   The `--label' was once called `--volume', but is not available under
+that name anymore.
+
+   You can also use `--label' to get a common information on all tapes
+of a series.  For having this information different in each series
+created through a single script used on a regular basis, just manage to
+get some date string as part of the label.  For example:
+
+     $ tar cfMV /dev/tape "Daily backup for `date +%Y-%m-%d`"
+     $ tar --create --file=/dev/tape --multi-volume \
+          --volume="Daily backup for `date +%Y-%m-%d`"
+
+   Also note that each label has its own date and time, which
+corresponds to when GNU `tar' initially attempted to write it, often
+soon after the operator launches `tar' or types the carriage return
+telling that the next tape is ready.  Comparing date labels does give
+an idea of tape throughput only if the delays for rewinding tapes and
+the operator switching them were negligible, which is usually not the
+case.
+
+   ---------- Footnotes ----------
+
+   (1) Previous versions of `tar' used full regular expression
+matching, or before that, only exact string matching, instead of
+wildcard matchers.  We decided for the sake of simplicity to use a
+uniform matching device through `tar'.
+
+
+File: tar.info,  Node: verify,  Next: Write Protection,  Prev: label,  Up: Media
+
+9.8 Verifying Data as It is Stored
+==================================
+
+`-W'
+`--verify'
+     Attempt to verify the archive after writing.
+
+   This option causes `tar' to verify the archive after writing it.
+Each volume is checked after it is written, and any discrepancies are
+recorded on the standard error output.
+
+   Verification requires that the archive be on a back-space-able
+medium.  This means pipes, some cartridge tape drives, and some other
+devices cannot be verified.
+
+   You can insure the accuracy of an archive by comparing files in the
+system with archive members.  `tar' can compare an archive to the file
+system as the archive is being written, to verify a write operation, or
+can compare a previously written archive, to insure that it is up to
+date.
+
+   To check for discrepancies in an archive immediately after it is
+written, use the `--verify' (`-W') option in conjunction with the
+`--create' operation.  When this option is specified, `tar' checks
+archive members against their counterparts in the file system, and
+reports discrepancies on the standard error.
+
+   To verify an archive, you must be able to read it from before the end
+of the last written entry.  This option is useful for detecting data
+errors on some tapes.  Archives written to pipes, some cartridge tape
+drives, and some other devices cannot be verified.
+
+   One can explicitly compare an already made archive with the file
+system by using the `--compare' (`--diff', `-d') option, instead of
+using the more automatic `--verify' option.  *Note compare::.
+
+   Note that these two options have a slightly different intent.  The
+`--compare' option checks how identical are the logical contents of some
+archive with what is on your disks, while the `--verify' option is
+really for checking if the physical contents agree and if the recording
+media itself is of dependable quality.  So, for the `--verify'
+operation, `tar' tries to defeat all in-memory cache pertaining to the
+archive, while it lets the speed optimization undisturbed for the
+`--compare' option.  If you nevertheless use `--compare' for media
+verification, you may have to defeat the in-memory cache yourself,
+maybe by opening and reclosing the door latch of your recording unit,
+forcing some doubt in your operating system about the fact this is
+really the same volume as the one just written or read.
+
+   The `--verify' option would not be necessary if drivers were indeed
+able to detect dependably all write failures.  This sometimes require
+many magnetic heads, some able to read after the writes occurred.  One
+would not say that drivers unable to detect all cases are necessarily
+flawed, as long as programming is concerned.
+
+   The `--verify' (`-W') option will not work in conjunction with the
+`--multi-volume' (`-M') option or the `--append' (`-r'), `--update'
+(`-u') and `--delete' operations.  *Note Operations::, for more
+information on these operations.
+
+   Also, since `tar' normally strips leading `/' from file names (*note
+absolute::), a command like `tar --verify -cf /tmp/foo.tar /etc' will
+work as desired only if the working directory is `/', as `tar' uses the
+archive's relative member names (e.g., `etc/motd') when verifying the
+archive.
+
+
+File: tar.info,  Node: Write Protection,  Prev: verify,  Up: Media
+
+9.9 Write Protection
+====================
+
+Almost all tapes and diskettes, and in a few rare cases, even disks can
+be "write protected", to protect data on them from being changed.  Once
+an archive is written, you should write protect the media to prevent
+the archive from being accidentally overwritten or deleted.  (This will
+protect the archive from being changed with a tape or floppy drive--it
+will not protect it from magnet fields or other physical hazards).
+
+   The write protection device itself is usually an integral part of the
+physical media, and can be a two position (write enabled/write
+disabled) switch, a notch which can be popped out or covered, a ring
+which can be removed from the center of a tape reel, or some other
+changeable feature.
+
+
+File: tar.info,  Node: Changes,  Next: Configuring Help Summary,  Prev: Media,  Up: Top
+
+Appendix A Changes
+******************
+
+This appendix lists some important user-visible changes between version
+GNU `tar' 1.17 and previous versions. An up-to-date version of this
+document is available at the GNU `tar' documentation page
+(http://www.gnu.org/software/tar/manual/changes.html).
+
+Use of globbing patterns when listing and extracting.
+     Previous versions of GNU tar assumed shell-style globbing when
+     extracting from or listing an archive.  For example:
+
+          $ tar xf foo.tar '*.c'
+
+     would extract all files whose names end in `.c'.  This behavior
+     was not documented and was incompatible with traditional tar
+     implementations.  Therefore, starting from version 1.15.91, GNU tar
+     no longer uses globbing by default.  For example, the above
+     invocation is now interpreted as a request to extract from the
+     archive the file named `*.c'.
+
+     To facilitate transition to the new behavior for those users who
+     got used to the previous incorrect one, `tar' will print a warning
+     if it finds out that a requested member was not found in the
+     archive and its name looks like a globbing pattern.  For example:
+
+          $ tar xf foo.tar  '*.c'
+          tar: Pattern matching characters used in file names. Please,
+          tar: use --wildcards to enable pattern matching, or --no-wildcards to
+          tar: suppress this warning.
+          tar: *.c: Not found in archive
+          tar: Error exit delayed from previous errors
+
+     To treat member names as globbing patterns, use -wildcards option.
+     If you want to tar to mimic the behavior of versions prior to
+     1.15.91, add this option to your `TAR_OPTIONS' variable.
+
+     *Note wildcards::, for the detailed discussion of the use of
+     globbing patterns by GNU `tar'.
+
+Use of short option `-o'.
+     Earlier versions of GNU `tar' understood `-o' command line option
+     as a synonym for `--old-archive'.
+
+     GNU `tar' starting from version 1.13.90 understands this option as
+     a synonym for `--no-same-owner'.  This is compatible with UNIX98
+     `tar' implementations.
+
+     However, to facilitate transition, `-o' option retains its old
+     semantics when it is used with one of archive-creation commands.
+     Users are encouraged to use `--format=oldgnu' instead.
+
+     It is especially important, since versions of GNU Automake up to
+     and including 1.8.4 invoke tar with this option to produce
+     distribution tarballs.  *Note v7: Formats, for the detailed
+     discussion of this issue and its implications.
+
+     .  *Note tar-v7: (automake)Options, for a description on how to
+     use various archive formats with `automake'.
+
+     Future versions of GNU `tar' will understand `-o' only as a
+     synonym for `--no-same-owner'.
+
+Use of short option `-l'
+     Earlier versions of GNU `tar' understood `-l' option as a synonym
+     for `--one-file-system'.  Since such usage contradicted to UNIX98
+     specification and harmed compatibility with other implementation,
+     it was declared deprecated in version 1.14.  However, to
+     facilitate transition to its new semantics, it was supported by
+     versions 1.15 and 1.15.90.  The present use of `-l' as a short
+     variant of `--check-links' was introduced in version 1.15.91.
+
+Use of options `--portability' and `--old-archive'
+     These options are deprecated.  Please use `--format=v7' instead.
+
+Use of option `--posix'
+     This option is deprecated.  Please use `--format=posix' instead.
+
+
+File: tar.info,  Node: Configuring Help Summary,  Next: Tar Internals,  Prev: Changes,  Up: Top
+
+Appendix B Configuring Help Summary
+***********************************
+
+Running `tar --help' displays the short `tar' option summary (*note
+help::). This summary is organized by "groups" of semantically close
+options. The options within each group are printed in the following
+order: a short option, eventually followed by a list of corresponding
+long option names, followed by a short description of the option. For
+example, here is an excerpt from the actual `tar --help' output:
+
+
+ Main operation mode:
+
+  -A, --catenate, --concatenate   append tar files to an archive
+  -c, --create               create a new archive
+  -d, --diff, --compare      find differences between archive and
+                             file system
+      --delete               delete from the archive
+
+   The exact visual representation of the help output is configurable
+via `ARGP_HELP_FMT' environment variable. The value of this variable is
+a comma-separated list of "format variable" assignments. There are two
+kinds of format variables. An "offset variable" keeps the offset of
+some part of help output text from the leftmost column on the screen. A
+"boolean" variable is a flag that toggles some output feature on or
+off. Depending on the type of the corresponding variable, there are two
+kinds of assignments:
+
+Offset assignment
+     The assignment to an offset variable has the following syntax:
+
+          VARIABLE=VALUE
+
+     where VARIABLE is the variable name, and VALUE is a numeric value
+     to be assigned to the variable.
+
+Boolean assignment
+     To assign `true' value to a variable, simply put this variable
+     name. To assign `false' value, prefix the variable name with
+     `no-'. For example:
+
+          # Assign `true' value:
+          dup-args
+          # Assign `false' value:
+          no-dup-args
+
+   Following variables are declared:
+
+ -- Help Output: boolean dup-args
+     If true, arguments for an option are shown with both short and long
+     options, even when a given option has both forms, for example:
+
+            -f ARCHIVE, --file=ARCHIVE use archive file or device ARCHIVE
+
+     If false, then if an option has both short and long forms, the
+     argument is only shown with the long one, for example:
+
+            -f, --file=ARCHIVE         use archive file or device ARCHIVE
+
+     and a message indicating that the argument is applicable to both
+     forms is printed below the options. This message can be disabled
+     using `dup-args-note' (see below).
+
+     The default is false.
+
+ -- Help Output: boolean dup-args-note
+     If this variable is true, which is the default, the following
+     notice is displayed at the end of the help output:
+
+          Mandatory or optional arguments to long options are also
+          mandatory or optional for any corresponding short options.
+
+     Setting `no-dup-args-note' inhibits this message. Normally, only
+     one of variables `dup-args' or `dup-args-note' should be set.
+
+ -- Help Output: offset short-opt-col
+     Column in which short options start. Default is 2.
+
+          $ tar --help|grep ARCHIVE
+            -f, --file=ARCHIVE   use archive file or device ARCHIVE
+          $ ARGP_HELP_FMT=short-opt-col=6 tar --help|grep ARCHIVE
+                -f, --file=ARCHIVE   use archive file or device ARCHIVE
+
+ -- Help Output: offset long-opt-col
+     Column in which long options start. Default is 6. For example:
+
+          $ tar --help|grep ARCHIVE
+            -f, --file=ARCHIVE   use archive file or device ARCHIVE
+          $ ARGP_HELP_FMT=long-opt-col=16 tar --help|grep ARCHIVE
+            -f,           --file=ARCHIVE   use archive file or device ARCHIVE
+
+ -- Help Output: offset doc-opt-col
+     Column in which "doc options" start.  A doc option isn't actually
+     an option, but rather an arbitrary piece of documentation that is
+     displayed in much the same manner as the options.  For example, in
+     the description of `--format' option:
+
+            -H, --format=FORMAT        create archive of the given format.
+
+           FORMAT is one of the following:
+
+              gnu                      GNU tar 1.13.x format
+              oldgnu                   GNU format as per tar <= 1.12
+              pax                      POSIX 1003.1-2001 (pax) format
+              posix                    same as pax
+              ustar                    POSIX 1003.1-1988 (ustar) format
+              v7                       old V7 tar format
+
+     the format names are doc options. Thus, if you set
+     `ARGP_HELP_FMT=doc-opt-col=6' the above part of the help output
+     will look as follows:
+
+            -H, --format=FORMAT        create archive of the given format.
+
+           FORMAT is one of the following:
+
+                  gnu                      GNU tar 1.13.x format
+                  oldgnu                   GNU format as per tar <= 1.12
+                  pax                      POSIX 1003.1-2001 (pax) format
+                  posix                    same as pax
+                  ustar                    POSIX 1003.1-1988 (ustar) format
+                  v7                       old V7 tar format
+
+ -- Help Output: offset opt-doc-col
+     Column in which option description starts. Default is 29.
+
+          $ tar --help|grep ARCHIVE
+            -f, --file=ARCHIVE         use archive file or device ARCHIVE
+          $ ARGP_HELP_FMT=opt-doc-col=19 tar --help|grep ARCHIVE
+            -f, --file=ARCHIVE   use archive file or device ARCHIVE
+          $ ARGP_HELP_FMT=opt-doc-col=9 tar --help|grep ARCHIVE
+            -f, --file=ARCHIVE
+                     use archive file or device ARCHIVE
+
+     Notice, that the description starts on a separate line if
+     `opt-doc-col' value is too small.
+
+ -- Help Output: offset header-col
+     Column in which "group headers" are printed.  A group header is a
+     descriptive text preceding an option group.  For example, in the
+     following text:
+
+
+      Main operation mode:
+
+       -A, --catenate, --concatenate   append tar files to
+                                  an archive
+       -c, --create               create a new archive
+      `Main operation mode:' is the group header.
+
+     The default value is 1.
+
+ -- Help Output: offset usage-indent
+     Indentation of wrapped usage lines. Affects `--usage' output.
+     Default is 12.
+
+ -- Help Output: offset rmargin
+     Right margin of the text output. Used for wrapping.
+
+
+File: tar.info,  Node: Tar Internals,  Next: Genfile,  Prev: Configuring Help Summary,  Up: Top
+
+Appendix C Tar Internals
+************************
+
+* Menu:
+
+* Standard::           Basic Tar Format
+* Extensions::         GNU Extensions to the Archive Format
+* Sparse Formats::     Storing Sparse Files
+* Snapshot Files::
+* Dumpdir::
+
+
+File: tar.info,  Node: Standard,  Next: Extensions,  Up: Tar Internals
+
+Basic Tar Format
+================
+
+     _(This message will disappear, once this node revised.)_
+
+While an archive may contain many files, the archive itself is a single
+ordinary file.  Like any other file, an archive file can be written to
+a storage device such as a tape or disk, sent through a pipe or over a
+network, saved on the active file system, or even stored in another
+archive.  An archive file is not easy to read or manipulate without
+using the `tar' utility or Tar mode in GNU Emacs.
+
+   Physically, an archive consists of a series of file entries
+terminated by an end-of-archive entry, which consists of two 512 blocks
+of zero bytes.  A file entry usually describes one of the files in the
+archive (an "archive member"), and consists of a file header and the
+contents of the file.  File headers contain file names and statistics,
+checksum information which `tar' uses to detect file corruption, and
+information about file types.
+
+   Archives are permitted to have more than one member with the same
+member name.  One way this situation can occur is if more than one
+version of a file has been stored in the archive.  For information
+about adding new versions of a file to an archive, see *note update::.
+
+   In addition to entries describing archive members, an archive may
+contain entries which `tar' itself uses to store information.  *Note
+label::, for an example of such an archive entry.
+
+   A `tar' archive file contains a series of blocks.  Each block
+contains `BLOCKSIZE' bytes.  Although this format may be thought of as
+being on magnetic tape, other media are often used.
+
+   Each file archived is represented by a header block which describes
+the file, followed by zero or more blocks which give the contents of
+the file.  At the end of the archive file there are two 512-byte blocks
+filled with binary zeros as an end-of-file marker.  A reasonable system
+should write such end-of-file marker at the end of an archive, but must
+not assume that such a block exists when reading an archive.  In
+particular GNU `tar' always issues a warning if it does not encounter
+it.
+
+   The blocks may be "blocked" for physical I/O operations.  Each
+record of N blocks (where N is set by the `--blocking-factor=512-SIZE'
+(`-b 512-SIZE') option to `tar') is written with a single `write ()'
+operation.  On magnetic tapes, the result of such a write is a single
+record.  When writing an archive, the last record of blocks should be
+written at the full size, with blocks after the zero block containing
+all zeros.  When reading an archive, a reasonable system should
+properly handle an archive whose last record is shorter than the rest,
+or which contains garbage records after a zero block.
+
+   The header block is defined in C as follows.  In the GNU `tar'
+distribution, this is part of file `src/tar.h':
+
+
+     /* tar Header Block, from POSIX 1003.1-1990.  */
+
+     /* POSIX header.  */
+
+     struct posix_header
+     {                              /* byte offset */
+       char name[100];               /*   0 */
+       char mode[8];                 /* 100 */
+       char uid[8];                  /* 108 */
+       char gid[8];                  /* 116 */
+       char size[12];                /* 124 */
+       char mtime[12];               /* 136 */
+       char chksum[8];               /* 148 */
+       char typeflag;                /* 156 */
+       char linkname[100];           /* 157 */
+       char magic[6];                /* 257 */
+       char version[2];              /* 263 */
+       char uname[32];               /* 265 */
+       char gname[32];               /* 297 */
+       char devmajor[8];             /* 329 */
+       char devminor[8];             /* 337 */
+       char prefix[155];             /* 345 */
+                                     /* 500 */
+     };
+
+     #define TMAGIC   "ustar"        /* ustar and a null */
+     #define TMAGLEN  6
+     #define TVERSION "00"           /* 00 and no null */
+     #define TVERSLEN 2
+
+     /* Values used in typeflag field.  */
+     #define REGTYPE  '0'            /* regular file */
+     #define AREGTYPE '\0'           /* regular file */
+     #define LNKTYPE  '1'            /* link */
+     #define SYMTYPE  '2'            /* reserved */
+     #define CHRTYPE  '3'            /* character special */
+     #define BLKTYPE  '4'            /* block special */
+     #define DIRTYPE  '5'            /* directory */
+     #define FIFOTYPE '6'            /* FIFO special */
+     #define CONTTYPE '7'            /* reserved */
+
+     #define XHDTYPE  'x'            /* Extended header referring to the
+                                        next file in the archive */
+     #define XGLTYPE  'g'            /* Global extended header */
+
+     /* Bits used in the mode field, values in octal.  */
+     #define TSUID    04000          /* set UID on execution */
+     #define TSGID    02000          /* set GID on execution */
+     #define TSVTX    01000          /* reserved */
+                                     /* file permissions */
+     #define TUREAD   00400          /* read by owner */
+     #define TUWRITE  00200          /* write by owner */
+     #define TUEXEC   00100          /* execute/search by owner */
+     #define TGREAD   00040          /* read by group */
+     #define TGWRITE  00020          /* write by group */
+     #define TGEXEC   00010          /* execute/search by group */
+     #define TOREAD   00004          /* read by other */
+     #define TOWRITE  00002          /* write by other */
+     #define TOEXEC   00001          /* execute/search by other */
+
+     /* tar Header Block, GNU extensions.  */
+
+     /* In GNU tar, SYMTYPE is for to symbolic links, and CONTTYPE is for
+        contiguous files, so maybe disobeying the `reserved' comment in POSIX
+        header description.  I suspect these were meant to be used this way, and
+        should not have really been `reserved' in the published standards.  */
+
+     /* *BEWARE* *BEWARE* *BEWARE* that the following information is still
+        boiling, and may change.  Even if the OLDGNU format description should be
+        accurate, the so-called GNU format is not yet fully decided.  It is
+        surely meant to use only extensions allowed by POSIX, but the sketch
+        below repeats some ugliness from the OLDGNU format, which should rather
+        go away.  Sparse files should be saved in such a way that they do *not*
+        require two passes at archive creation time.  Huge files get some POSIX
+        fields to overflow, alternate solutions have to be sought for this.  */
+
+     /* Descriptor for a single file hole.  */
+
+     struct sparse
+     {                              /* byte offset */
+       char offset[12];              /*   0 */
+       char numbytes[12];            /*  12 */
+                                     /*  24 */
+     };
+
+     /* Sparse files are not supported in POSIX ustar format.  For sparse files
+        with a POSIX header, a GNU extra header is provided which holds overall
+        sparse information and a few sparse descriptors.  When an old GNU header
+        replaces both the POSIX header and the GNU extra header, it holds some
+        sparse descriptors too.  Whether POSIX or not, if more sparse descriptors
+        are still needed, they are put into as many successive sparse headers as
+        necessary.  The following constants tell how many sparse descriptors fit
+        in each kind of header able to hold them.  */
+
+     #define SPARSES_IN_EXTRA_HEADER  16
+     #define SPARSES_IN_OLDGNU_HEADER 4
+     #define SPARSES_IN_SPARSE_HEADER 21
+
+     /* Extension header for sparse files, used immediately after the GNU extra
+        header, and used only if all sparse information cannot fit into that
+        extra header.  There might even be many such extension headers, one after
+        the other, until all sparse information has been recorded.  */
+
+     struct sparse_header
+     {                              /* byte offset */
+       struct sparse sp[SPARSES_IN_SPARSE_HEADER];
+                                     /*   0 */
+       char isextended;              /* 504 */
+                                     /* 505 */
+     };
+
+     /* The old GNU format header conflicts with POSIX format in such a way that
+        POSIX archives may fool old GNU tar's, and POSIX tar's might well be
+        fooled by old GNU tar archives.  An old GNU format header uses the space
+        used by the prefix field in a POSIX header, and cumulates information
+        normally found in a GNU extra header.  With an old GNU tar header, we
+        never see any POSIX header nor GNU extra header.  Supplementary sparse
+        headers are allowed, however.  */
+
+     struct oldgnu_header
+     {                              /* byte offset */
+       char unused_pad1[345];        /*   0 */
+       char atime[12];               /* 345 Incr. archive: atime of the file */
+       char ctime[12];               /* 357 Incr. archive: ctime of the file */
+       char offset[12];              /* 369 Multivolume archive: the offset of
+                                        the start of this volume */
+       char longnames[4];            /* 381 Not used */
+       char unused_pad2;             /* 385 */
+       struct sparse sp[SPARSES_IN_OLDGNU_HEADER];
+                                     /* 386 */
+       char isextended;              /* 482 Sparse file: Extension sparse header
+                                        follows */
+       char realsize[12];            /* 483 Sparse file: Real size*/
+                                     /* 495 */
+     };
+
+     /* OLDGNU_MAGIC uses both magic and version fields, which are contiguous.
+        Found in an archive, it indicates an old GNU header format, which will be
+        hopefully become obsolescent.  With OLDGNU_MAGIC, uname and gname are
+        valid, though the header is not truly POSIX conforming.  */
+     #define OLDGNU_MAGIC "ustar  "  /* 7 chars and a null */
+
+     /* The standards committee allows only capital A through capital Z for
+        user-defined expansion.  Other letters in use include:
+
+        'A' Solaris Access Control List
+        'E' Solaris Extended Attribute File
+        'I' Inode only, as in 'star'
+        'N' Obsolete GNU tar, for file names that do not fit into the main header.
+        'X' POSIX 1003.1-2001 eXtended (VU version)  */
+
+     /* This is a dir entry that contains the names of files that were in the
+        dir at the time the dump was made.  */
+     #define GNUTYPE_DUMPDIR 'D'
+
+     /* Identifies the *next* file on the tape as having a long linkname.  */
+     #define GNUTYPE_LONGLINK 'K'
+
+     /* Identifies the *next* file on the tape as having a long name.  */
+     #define GNUTYPE_LONGNAME 'L'
+
+     /* This is the continuation of a file that began on another volume.  */
+     #define GNUTYPE_MULTIVOL 'M'
+
+     /* This is for sparse files.  */
+     #define GNUTYPE_SPARSE 'S'
+
+     /* This file is a tape/volume header.  Ignore it on extraction.  */
+     #define GNUTYPE_VOLHDR 'V'
+
+     /* Solaris extended header */
+     #define SOLARIS_XHDTYPE 'X'
+
+     /* Jo"rg Schilling star header */
+
+     struct star_header
+     {                              /* byte offset */
+       char name[100];               /*   0 */
+       char mode[8];                 /* 100 */
+       char uid[8];                  /* 108 */
+       char gid[8];                  /* 116 */
+       char size[12];                /* 124 */
+       char mtime[12];               /* 136 */
+       char chksum[8];               /* 148 */
+       char typeflag;                /* 156 */
+       char linkname[100];           /* 157 */
+       char magic[6];                /* 257 */
+       char version[2];              /* 263 */
+       char uname[32];               /* 265 */
+       char gname[32];               /* 297 */
+       char devmajor[8];             /* 329 */
+       char devminor[8];             /* 337 */
+       char prefix[131];             /* 345 */
+       char atime[12];               /* 476 */
+       char ctime[12];               /* 488 */
+                                     /* 500 */
+     };
+
+     #define SPARSES_IN_STAR_HEADER      4
+     #define SPARSES_IN_STAR_EXT_HEADER  21
+
+     struct star_in_header
+     {
+       char fill[345];       /*   0  Everything that is before t_prefix */
+       char prefix[1];       /* 345  t_name prefix */
+       char fill2;           /* 346  */
+       char fill3[8];        /* 347  */
+       char isextended;      /* 355  */
+       struct sparse sp[SPARSES_IN_STAR_HEADER]; /* 356  */
+       char realsize[12];    /* 452  Actual size of the file */
+       char offset[12];      /* 464  Offset of multivolume contents */
+       char atime[12];       /* 476  */
+       char ctime[12];       /* 488  */
+       char mfill[8];        /* 500  */
+       char xmagic[4];       /* 508  "tar" */
+     };
+
+     struct star_ext_header
+     {
+       struct sparse sp[SPARSES_IN_STAR_EXT_HEADER];
+       char isextended;
+     };
+
+   All characters in header blocks are represented by using 8-bit
+characters in the local variant of ASCII.  Each field within the
+structure is contiguous; that is, there is no padding used within the
+structure.  Each character on the archive medium is stored contiguously.
+
+   Bytes representing the contents of files (after the header block of
+each file) are not translated in any way and are not constrained to
+represent characters in any character set.  The `tar' format does not
+distinguish text files from binary files, and no translation of file
+contents is performed.
+
+   The `name', `linkname', `magic', `uname', and `gname' are
+null-terminated character strings.  All other fields are zero-filled
+octal numbers in ASCII.  Each numeric field of width W contains W minus
+1 digits, and a null.
+
+   The `name' field is the file name of the file, with directory names
+(if any) preceding the file name, separated by slashes.
+
+   The `mode' field provides nine bits specifying file permissions and
+three bits to specify the Set UID, Set GID, and Save Text ("sticky")
+modes.  Values for these bits are defined above.  When special
+permissions are required to create a file with a given mode, and the
+user restoring files from the archive does not hold such permissions,
+the mode bit(s) specifying those special permissions are ignored.
+Modes which are not supported by the operating system restoring files
+from the archive will be ignored.  Unsupported modes should be faked up
+when creating or updating an archive; e.g., the group permission could
+be copied from the _other_ permission.
+
+   The `uid' and `gid' fields are the numeric user and group ID of the
+file owners, respectively.  If the operating system does not support
+numeric user or group IDs, these fields should be ignored.
+
+   The `size' field is the size of the file in bytes; linked files are
+archived with this field specified as zero.
+
+   The `mtime' field is the data modification time of the file at the
+time it was archived.  It is the ASCII representation of the octal
+value of the last time the file's contents were modified, represented
+as an integer number of seconds since January 1, 1970, 00:00
+Coordinated Universal Time.
+
+   The `chksum' field is the ASCII representation of the octal value of
+the simple sum of all bytes in the header block.  Each 8-bit byte in
+the header is added to an unsigned integer, initialized to zero, the
+precision of which shall be no less than seventeen bits.  When
+calculating the checksum, the `chksum' field is treated as if it were
+all blanks.
+
+   The `typeflag' field specifies the type of file archived.  If a
+particular implementation does not recognize or permit the specified
+type, the file will be extracted as if it were a regular file.  As this
+action occurs, `tar' issues a warning to the standard error.
+
+   The `atime' and `ctime' fields are used in making incremental
+backups; they store, respectively, the particular file's access and
+status change times.
+
+   The `offset' is used by the `--multi-volume' (`-M') option, when
+making a multi-volume archive.  The offset is number of bytes into the
+file that we need to restart at to continue the file on the next tape,
+i.e., where we store the location that a continued file is continued at.
+
+   The following fields were added to deal with sparse files.  A file
+is "sparse" if it takes in unallocated blocks which end up being
+represented as zeros, i.e., no useful data.  A test to see if a file is
+sparse is to look at the number blocks allocated for it versus the
+number of characters in the file; if there are fewer blocks allocated
+for the file than would normally be allocated for a file of that size,
+then the file is sparse.  This is the method `tar' uses to detect a
+sparse file, and once such a file is detected, it is treated
+differently from non-sparse files.
+
+   Sparse files are often `dbm' files, or other database-type files
+which have data at some points and emptiness in the greater part of the
+file.  Such files can appear to be very large when an `ls -l' is done
+on them, when in truth, there may be a very small amount of important
+data contained in the file.  It is thus undesirable to have `tar' think
+that it must back up this entire file, as great quantities of room are
+wasted on empty blocks, which can lead to running out of room on a tape
+far earlier than is necessary.  Thus, sparse files are dealt with so
+that these empty blocks are not written to the tape.  Instead, what is
+written to the tape is a description, of sorts, of the sparse file:
+where the holes are, how big the holes are, and how much data is found
+at the end of the hole.  This way, the file takes up potentially far
+less room on the tape, and when the file is extracted later on, it will
+look exactly the way it looked beforehand.  The following is a
+description of the fields used to handle a sparse file:
+
+   The `sp' is an array of `struct sparse'.  Each `struct sparse'
+contains two 12-character strings which represent an offset into the
+file and a number of bytes to be written at that offset.  The offset is
+absolute, and not relative to the offset in preceding array element.
+
+   The header can hold four of these `struct sparse' at the moment; if
+more are needed, they are not stored in the header.
+
+   The `isextended' flag is set when an `extended_header' is needed to
+deal with a file.  Note that this means that this flag can only be set
+when dealing with a sparse file, and it is only set in the event that
+the description of the file will not fit in the allotted room for
+sparse structures in the header.  In other words, an extended_header is
+needed.
+
+   The `extended_header' structure is used for sparse files which need
+more sparse structures than can fit in the header.  The header can fit
+4 such structures; if more are needed, the flag `isextended' gets set
+and the next block is an `extended_header'.
+
+   Each `extended_header' structure contains an array of 21 sparse
+structures, along with a similar `isextended' flag that the header had.
+There can be an indeterminate number of such `extended_header's to
+describe a sparse file.
+
+`REGTYPE'
+`AREGTYPE'
+     These flags represent a regular file.  In order to be compatible
+     with older versions of `tar', a `typeflag' value of `AREGTYPE'
+     should be silently recognized as a regular file.  New archives
+     should be created using `REGTYPE'.  Also, for backward
+     compatibility, `tar' treats a regular file whose name ends with a
+     slash as a directory.
+
+`LNKTYPE'
+     This flag represents a file linked to another file, of any type,
+     previously archived.  Such files are identified in Unix by each
+     file having the same device and inode number.  The linked-to name
+     is specified in the `linkname' field with a trailing null.
+
+`SYMTYPE'
+     This represents a symbolic link to another file.  The linked-to
+     name is specified in the `linkname' field with a trailing null.
+
+`CHRTYPE'
+`BLKTYPE'
+     These represent character special files and block special files
+     respectively.  In this case the `devmajor' and `devminor' fields
+     will contain the major and minor device numbers respectively.
+     Operating systems may map the device specifications to their own
+     local specification, or may ignore the entry.
+
+`DIRTYPE'
+     This flag specifies a directory or sub-directory.  The directory
+     name in the `name' field should end with a slash.  On systems where
+     disk allocation is performed on a directory basis, the `size' field
+     will contain the maximum number of bytes (which may be rounded to
+     the nearest disk block allocation unit) which the directory may
+     hold.  A `size' field of zero indicates no such limiting.  Systems
+     which do not support limiting in this manner should ignore the
+     `size' field.
+
+`FIFOTYPE'
+     This specifies a FIFO special file.  Note that the archiving of a
+     FIFO file archives the existence of this file and not its contents.
+
+`CONTTYPE'
+     This specifies a contiguous file, which is the same as a normal
+     file except that, in operating systems which support it, all its
+     space is allocated contiguously on the disk.  Operating systems
+     which do not allow contiguous allocation should silently treat this
+     type as a normal file.
+
+`A' ... `Z'
+     These are reserved for custom implementations.  Some of these are
+     used in the GNU modified format, as described below.
+
+
+   Other values are reserved for specification in future revisions of
+the P1003 standard, and should not be used by any `tar' program.
+
+   The `magic' field indicates that this archive was output in the
+P1003 archive format.  If this field contains `TMAGIC', the `uname' and
+`gname' fields will contain the ASCII representation of the owner and
+group of the file respectively.  If found, the user and group IDs are
+used rather than the values in the `uid' and `gid' fields.
+
+   For references, see ISO/IEC 9945-1:1990 or IEEE Std 1003.1-1990,
+pages 169-173 (section 10.1) for `Archive/Interchange File Format'; and
+IEEE Std 1003.2-1992, pages 380-388 (section 4.48) and pages 936-940
+(section E.4.48) for `pax - Portable archive interchange'.
+
+
+File: tar.info,  Node: Extensions,  Next: Sparse Formats,  Prev: Standard,  Up: Tar Internals
+
+GNU Extensions to the Archive Format
+====================================
+
+     _(This message will disappear, once this node revised.)_
+
+The GNU format uses additional file types to describe new types of
+files in an archive.  These are listed below.
+
+`GNUTYPE_DUMPDIR'
+`'D''
+     This represents a directory and a list of files created by the
+     `--incremental' (`-G') option.  The `size' field gives the total
+     size of the associated list of files.  Each file name is preceded
+     by either a `Y' (the file should be in this archive) or an `N'.
+     (The file is a directory, or is not stored in the archive.)  Each
+     file name is terminated by a null.  There is an additional null
+     after the last file name.
+
+`GNUTYPE_MULTIVOL'
+`'M''
+     This represents a file continued from another volume of a
+     multi-volume archive created with the `--multi-volume' (`-M')
+     option.  The original type of the file is not given here.  The
+     `size' field gives the maximum size of this piece of the file
+     (assuming the volume does not end before the file is written out).
+     The `offset' field gives the offset from the beginning of the
+     file where this part of the file begins.  Thus `size' plus
+     `offset' should equal the original size of the file.
+
+`GNUTYPE_SPARSE'
+`'S''
+     This flag indicates that we are dealing with a sparse file.  Note
+     that archiving a sparse file requires special operations to find
+     holes in the file, which mark the positions of these holes, along
+     with the number of bytes of data to be found after the hole.
+
+`GNUTYPE_VOLHDR'
+`'V''
+     This file type is used to mark the volume header that was given
+     with the `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') option when
+     the archive was created.  The `name' field contains the `name'
+     given after the `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL')
+     option.  The `size' field is zero.  Only the first file in each
+     volume of an archive should have this type.
+
+
+   You may have trouble reading a GNU format archive on a non-GNU
+system if the options `--incremental' (`-G'), `--multi-volume' (`-M'),
+`--sparse' (`-S'), or `--label=ARCHIVE-LABEL' (`-V ARCHIVE-LABEL') were
+used when writing the archive.  In general, if `tar' does not use the
+GNU-added fields of the header, other versions of `tar' should be able
+to read the archive.  Otherwise, the `tar' program will give an error,
+the most likely one being a checksum error.
+
+
+File: tar.info,  Node: Sparse Formats,  Next: Snapshot Files,  Prev: Extensions,  Up: Tar Internals
+
+Storing Sparse Files
+====================
+
+The notion of sparse file, and the ways of handling it from the point
+of view of GNU `tar' user have been described in detail in *note
+sparse::.  This chapter describes the internal format GNU `tar' uses to
+store such files.
+
+   The support for sparse files in GNU `tar' has a long history.  The
+earliest version featuring this support that I was able to find was
+1.09, released in November, 1990.  The format introduced back then is
+called "old GNU" sparse format and in spite of the fact that its design
+contained many flaws, it was the only format GNU `tar' supported until
+version 1.14 (May, 2004), which introduced initial support for sparse
+archives in PAX archives (*note posix::).  This format was not free
+from design flows, either and it was subsequently improved in versions
+1.15.2 (November, 2005) and 1.15.92 (June, 2006).
+
+   In addition to GNU sparse format, GNU `tar' is able to read and
+extract sparse files archived by `star'.
+
+   The following subsections describe each format in detail.
+
+* Menu:
+
+* Old GNU Format::
+* PAX 0::                PAX Format, Versions 0.0 and 0.1
+* PAX 1::                PAX Format, Version 1.0
+
+
+File: tar.info,  Node: Old GNU Format,  Next: PAX 0,  Up: Sparse Formats
+
+C.0.1 Old GNU Format
+--------------------
+
+The format introduced some time around 1990 (v. 1.09).  It was designed
+on top of standard `ustar' headers in such an unfortunate way that some
+of its fields overwrote fields required by POSIX.
+
+   An old GNU sparse header is designated by type `S'
+(`GNUTYPE_SPARSE') and has the following layout:
+
+Offset  Size    Name           Data type      Contents
+---------------------------------------------------------------------------- 
+0       345                    N/A            Not used.
+345     12      atime          Number         `atime' of the file.
+357     12      ctime          Number         `ctime' of the file .
+369     12      offset         Number         For multivolume archives:
+                                              the offset of the start of
+                                              this volume.
+381     4                      N/A            Not used.
+385     1                      N/A            Not used.
+386     96      sp             `sparse_header'(4 entries) File map.
+482     1       isextended     Bool           `1' if an extension sparse
+                                              header follows, `0'
+                                              otherwise.
+483     12      realsize       Number         Real size of the file.
+
+   Each of `sparse_header' object at offset 386 describes a single data
+chunk. It has the following structure:
+
+Offset  Size    Data type      Contents
+--------------------------------------------------------------------------- 
+0       12      Number         Offset of the beginning of the chunk.
+12      12      Number         Size of the chunk.
+
+   If the member contains more than four chunks, the `isextended' field
+of the header has the value `1' and the main header is followed by one
+or more "extension headers".  Each such header has the following
+structure:
+
+Offset  Size    Name           Data type      Contents
+---------------------------------------------------------------------------- 
+0       21      sp             `sparse_header' (21 entires) File map.
+504     1       isextended     Bool           `1' if an extension sparse
+                                              header follows, or `0'
+                                              otherwise.
+
+   A header with `isextended=0' ends the map.
+
+
+File: tar.info,  Node: PAX 0,  Next: PAX 1,  Prev: Old GNU Format,  Up: Sparse Formats
+
+C.0.2 PAX Format, Versions 0.0 and 0.1
+--------------------------------------
+
+There are two formats available in this branch.  The version `0.0' is
+the initial version of sparse format used by `tar' versions
+1.14-1.15.1.  The sparse file map is kept in extended (`x') PAX header
+variables:
+
+`GNU.sparse.size'
+     Real size of the stored file
+
+`GNU.sparse.numblocks'
+     Number of blocks in the sparse map
+
+`GNU.sparse.offset'
+     Offset of the data block
+
+`GNU.sparse.numbytes'
+     Size of the data block
+
+   The latter two variables repeat for each data block, so the overall
+structure is like this:
+
+     GNU.sparse.size=SIZE
+     GNU.sparse.numblocks=NUMBLOCKS
+     repeat NUMBLOCKS times
+       GNU.sparse.offset=OFFSET
+       GNU.sparse.numbytes=NUMBYTES
+     end repeat
+
+   This format presented the following two problems:
+
+  1. Whereas the POSIX specification allows a variable to appear
+     multiple times in a header, it requires that only the last
+     occurrence be meaningful.  Thus, multiple occurrences of
+     `GNU.sparse.offset' and `GNU.sparse.numbytes' are conflicting with
+     the POSIX specs.
+
+  2. Attempting to extract such archives using a third-party `tar's
+     results in extraction of sparse files in _compressed form_.  If
+     the `tar' implementation in question does not support POSIX
+     format, it will also extract a file containing extension header
+     attributes.  This file can be used to expand the file to its
+     original state.  However, posix-aware `tar's will usually ignore
+     the unknown variables, which makes restoring the file more
+     difficult.  *Note Extraction of sparse members in v.0.0 format:
+     extracting sparse v.0.x, for the detailed description of how to
+     restore such members using non-GNU `tar's.
+
+   GNU `tar' 1.15.2 introduced sparse format version `0.1', which
+attempted to solve these problems.  As its predecessor, this format
+stores sparse map in the extended POSIX header.  It retains
+`GNU.sparse.size' and `GNU.sparse.numblocks' variables, but instead of
+`GNU.sparse.offset'/`GNU.sparse.numbytes' pairs it uses a single
+variable:
+
+`GNU.sparse.map'
+     Map of non-null data chunks.  It is a string consisting of
+     comma-separated values "OFFSET,SIZE[,OFFSET-1,SIZE-1...]"
+
+   To address the 2nd problem, the `name' field in `ustar' is replaced
+with a special name, constructed using the following pattern:
+
+     %d/GNUSparseFile.%p/%f
+
+   The real name of the sparse file is stored in the variable
+`GNU.sparse.name'.  Thus, those `tar' implementations that are not
+aware of GNU extensions will at least extract the files into separate
+directories, giving the user a possibility to expand it afterwards.
+*Note Extraction of sparse members in v.0.1 format: extracting sparse
+v.0.x, for the detailed description of how to restore such members
+using non-GNU `tar's.
+
+   The resulting `GNU.sparse.map' string can be _very_ long.  Although
+POSIX does not impose any limit on the length of a `x' header variable,
+this possibly can confuse some tars.
+
+
+File: tar.info,  Node: PAX 1,  Prev: PAX 0,  Up: Sparse Formats
+
+C.0.3 PAX Format, Version 1.0
+-----------------------------
+
+The version `1.0' of sparse format was introduced with GNU `tar'
+1.15.92.  Its main objective was to make the resulting file extractable
+with little effort even by non-posix aware `tar' implementations.
+Starting from this version, the extended header preceding a sparse
+member always contains the following variables that identify the format
+being used:
+
+`GNU.sparse.major'
+     Major version
+
+`GNU.sparse.minor'
+     Minor version
+
+   The `name' field in `ustar' header contains a special name,
+constructed using the following pattern:
+
+     %d/GNUSparseFile.%p/%f
+
+   The real name of the sparse file is stored in the variable
+`GNU.sparse.name'.  The real size of the file is stored in the variable
+`GNU.sparse.realsize'.
+
+   The sparse map itself is stored in the file data block, preceding
+the actual file data.  It consists of a series of octal numbers of
+arbitrary length, delimited by newlines. The map is padded with nulls
+to the nearest block boundary.
+
+   The first number gives the number of entries in the map. Following
+are map entries, each one consisting of two numbers giving the offset
+and size of the data block it describes.
+
+   The format is designed in such a way that non-posix aware tars and
+tars not supporting `GNU.sparse.*' keywords will extract each sparse
+file in its condensed form with the file map prepended and will place it
+into a separate directory.  Then, using a simple program it would be
+possible to expand the file to its original form even without GNU `tar'.
+*Note Sparse Recovery::, for the detailed information on how to extract
+sparse members without GNU `tar'.
+
+
+File: tar.info,  Node: Snapshot Files,  Next: Dumpdir,  Prev: Sparse Formats,  Up: Tar Internals
+
+Format of the Incremental Snapshot Files
+========================================
+
+A "snapshot file" (or "directory file") is created during incremental
+backups (*note Incremental Dumps::).  It contains the status of the
+file system at the time of the dump and is used to determine which
+files were modified since the last backup.
+
+   GNU `tar' version 1.17 supports two snapshot file formats.  The
+first format, called "format 0", is the one used by GNU `tar' versions
+up to 1.15.1. The second format, called "format 1" is an extended
+version of this format, that contains more metadata and allows for
+further extensions.
+
+   `Format 0' snapshot file begins with a line containing a decimal
+number that represents the UNIX timestamp of the beginning of the last
+archivation. This line is followed by directory metadata descriptions,
+one per line. Each description has the following format:
+
+     [NFS]DEV INODE NAME
+
+where optional NFS is a single plus character (`+') if this directory
+is located on an NFS-mounted partition, DEV and INODE are the device
+and inode numbers of the directory, and NAME is the directory name.
+
+   `Format 1' snapshot file begins with a line specifying the format of
+the file. This line has the following structure:
+
+     `GNU tar-'TAR-VERSION`-'INCR-FORMAT-VERSION
+
+where TAR-VERSION is the version of GNU `tar' implementation that
+created this snapshot, and INCR-FORMAT-VERSION is the version number of
+the snapshot format (in this case `1').
+
+   The following line contains two decimal numbers, representing the
+time of the last backup. First number is the number of seconds, the
+second one is the number of nanoseconds, since the beginning of the
+epoch.
+
+   Following lines contain directory metadata, one line per directory.
+The line format is:
+
+     [NFS]MTIME-SEC MTIME-NSEC DEV INODE NAME
+
+where MTIME-SEC and MTIME-NSEC represent the last modification time of
+this directory with nanosecond precision; NFS, DEV, INODE and NAME have
+the same meaning as with `format 0'.
+
+
+File: tar.info,  Node: Dumpdir,  Prev: Snapshot Files,  Up: Tar Internals
+
+Dumpdir
+=======
+
+Incremental archives keep information about contents of each dumped
+directory in special data blocks called "dumpdirs".
+
+   Dumpdir is a sequence of entries of the following form:
+
+     C FILENAME \0
+
+where C is one of the "control codes" described below, FILENAME is the
+name of the file C operates upon, and `\0' represents a nul character
+(ASCII 0).  The white space characters were added for readability, real
+dumpdirs do not contain them.
+
+   Each dumpdir ends with a single nul character.
+
+   The following table describes control codes and their meanings:
+
+`Y'
+     FILENAME is contained in the archive.
+
+`N'
+     FILENAME was present in the directory at the time the archive was
+     made, yet it was not dumped to the archive, because it had not
+     changed since the last backup.
+
+`D'
+     FILENAME is a directory.
+
+`R'
+     This code requests renaming of the FILENAME to the name specified
+     with the following `T' command.
+
+`T'
+     Specify target file name for `R' command (see below).
+
+`X'
+     Specify "temporary directory" name for a rename operation (see
+     below).
+
+   Codes `Y', `N' and `D' require FILENAME argument to be a relative
+file name to the directory this dumpdir describes, whereas codes `R',
+`T' and `X' require their argument to be an absolute file name.
+
+   The three codes `R', `T' and `X' specify a "renaming operation".  In
+the simplest case it is:
+
+     R`source'\0T`dest'\0
+
+which means "rename file `source' to file `dest'".
+
+   However, there are cases that require using a "temporary directory".
+For example, consider the following scenario:
+
+  1. Previous run dumped a directory `foo' which contained the
+     following three directories:
+
+          a
+          b
+          c
+
+  2. They were renamed _cyclically_, so that:
+
+          `a' became `b'
+          `b' became `c'
+          `c' became `a'
+
+  3. New incremental dump was made.
+
+   This case cannot be handled by three successive renames, since
+renaming `a' to `b' will destroy existing directory.  To handle such
+case a temporary directory is required. GNU `tar' will create the
+following dumpdir (newlines have been added for readability):
+
+     Xfoo\0
+     Rfoo/a\0T\0
+     Rfoo/b\0Tfoo/c\0
+     Rfoo/c\0Tfoo/a\0
+     R\0Tfoo/a\0
+
+   The first command, `Xfoo\0', instructs the extractor to create a
+temporary directory in the directory `foo'.  Second command,
+`Rfoo/aT\0', says "rename file `foo/a' to the temporary directory that
+has just been created" (empty file name after a command means use
+temporary directory).  Third and fourth commands work as usual, and,
+finally, the last command, `R\0Tfoo/a\0' tells tar to rename the
+temporary directory to `foo/a'.
+
+   The exact placement of a dumpdir in the archive depends on the
+archive format (*note Formats::):
+
+   * PAX archives
+
+     In PAX archives, dumpdir is stored in the extended header of the
+     corresponding directory, in variable `GNU.dumpdir'.
+
+   * GNU and old GNU archives
+
+     These formats implement special header type `D', which is similar
+     to ustar header `5' (directory), except that it precedes a data
+     block containing the dumpdir.
+
+
+File: tar.info,  Node: Genfile,  Next: Free Software Needs Free Documentation,  Prev: Tar Internals,  Up: Top
+
+Appendix D Genfile
+******************
+
+This appendix describes `genfile', an auxiliary program used in the GNU
+tar testsuite. If you are not interested in developing GNU tar, skip
+this appendix.
+
+   Initially, `genfile' was used to generate data files for the
+testsuite, hence its name. However, new operation modes were being
+implemented as the testsuite grew more sophisticated, and now `genfile'
+is a multi-purpose instrument.
+
+   There are three basic operation modes:
+
+File Generation
+     This is the default mode. In this mode, `genfile' generates data
+     files.
+
+File Status
+     In this mode `genfile' displays status of specified files.
+
+Synchronous Execution.
+     In this mode `genfile' executes the given program with
+     `--checkpoint' option and executes a set of actions when specified
+     checkpoints are reached.
+
+* Menu:
+
+* Generate Mode::     File Generation Mode.
+* Status Mode::       File Status Mode.
+* Exec Mode::         Synchronous Execution mode.
+
+
+File: tar.info,  Node: Generate Mode,  Next: Status Mode,  Up: Genfile
+
+D.1 Generate Mode
+=================
+
+In this mode `genfile' creates a data file for the test suite. The size
+of the file is given with the `--length' (`-l') option. By default the
+file contents is written to the standard output, this can be changed
+using `--file' (`-f') command line option. Thus, the following two
+commands are equivalent:
+
+     genfile --length 100 > outfile
+     genfile --length 100 --file outfile
+
+   If `--length' is not given, `genfile' will generate an empty
+(zero-length) file.
+
+   The command line option `--seek=N' istructs `genfile' to skip the
+given number of bytes (N) in the output file before writing to it.  It
+is similar to the `seek=N' of the `dd' utility.
+
+   You can instruct `genfile' to create several files at one go, by
+giving it `--files-from' (`-T') option followed by a name of file
+containing a list of file names. Using dash (`-') instead of the file
+name causes `genfile' to read file list from the standard input. For
+example:
+
+     # Read file names from file `file.list'
+     genfile --files-from file.list
+     # Read file names from standard input
+     genfile --files-from -
+
+   The list file is supposed to contain one file name per line. To use
+file lists separated by ASCII NUL character, use `--null' (`-0')
+command line option:
+
+     genfile --null --files-from file.list
+
+   The default data pattern for filling the generated file consists of
+first 256 letters of ASCII code, repeated enough times to fill the
+entire file. This behavior can be changed with `--pattern' option. This
+option takes a mandatory argument, specifying pattern name to use.
+Currently two patterns are implemented:
+
+`--pattern=default'
+     The default pattern as described above.
+
+`--pattern=zero'
+     Fills the file with zeroes.
+
+   If no file name was given, the program exits with the code `0'.
+Otherwise, it exits with `0' only if it was able to create a file of
+the specified length.
+
+   Special option `--sparse' (`-s') instructs `genfile' to create a
+sparse file. Sparse files consist of "data fragments", separated by
+"holes" or blocks of zeros. On many operating systems, actual disk
+storage is not allocated for holes, but they are counted in the length
+of the file. To create a sparse file, `genfile' should know where to
+put data fragments, and what data to use to fill them. So, when
+`--sparse' is given the rest of the command line specifies a so-called
+"file map".
+
+   The file map consists of any number of "fragment descriptors". Each
+descriptor is composed of two values: a number, specifying fragment
+offset from the end of the previous fragment or, for the very first
+fragment, from the beginning of the file, and "contents string", i.e.,
+a string of characters, specifying the pattern to fill the fragment
+with. File offset can be suffixed with the following quantifiers:
+
+`k'
+`K'
+     The number is expressed in kilobytes.
+
+`m'
+`M'
+     The number is expressed in megabytes.
+
+`g'
+`G'
+     The number is expressed in gigabytes.
+
+   For each letter in contents string `genfile' will generate a "block"
+of data, filled with this letter and will write it to the fragment. The
+size of block is given by `--block-size' option. It defaults to 512.
+Thus, if the string consists of N characters, the resulting file
+fragment will contain `N*BLOCK-SIZE' of data.
+
+   Last fragment descriptor can have only file offset part. In this
+case `genfile' will create a hole at the end of the file up to the
+given offset.
+
+   For example, consider the following invocation:
+
+     genfile --sparse --file sparsefile 0 ABCD 1M EFGHI 2000K
+
+It will create 3101184-bytes long file of the following structure:
+
+Offset                    Length         Contents
+0                         4*512=2048     Four 512-byte blocks, filled
+                                         with letters `A', `B', `C' and
+                                         `D'.
+2048                      1046528        Zero bytes
+1050624                   5*512=2560     Five blocks, filled with letters
+                                         `E', `F', `G', `H', `I'.
+1053184                   2048000        Zero bytes
+
+   The exit code of `genfile --status' command is `0' only if created
+file is actually sparse.
+
+
+File: tar.info,  Node: Status Mode,  Next: Exec Mode,  Prev: Generate Mode,  Up: Genfile
+
+D.2 Status Mode
+===============
+
+In status mode, `genfile' prints file system status for each file
+specified in the command line. This mode is toggled by `--stat' (`-S')
+command line option. An optional argument to this option specifies
+output "format": a comma-separated list of `struct stat' fields to be
+displayed. This list can contain following identifiers :
+
+name
+     The file name.
+
+dev
+st_dev
+     Device number in decimal.
+
+ino
+st_ino
+     Inode number.
+
+mode[.NUMBER]
+st_mode[.NUMBER]
+     File mode in octal.  Optional NUMBER specifies octal mask to be
+     applied to the mode before outputting.  For example, `--stat
+     mode.777' will preserve lower nine bits of it.  Notice, that you
+     can use any punctuation character in place of `.'.
+
+nlink
+st_nlink
+     Number of hard links.
+
+uid
+st_uid
+     User ID of owner.
+
+gid
+st_gid
+     Group ID of owner.
+
+size
+st_size
+     File size in decimal.
+
+blksize
+st_blksize
+     The size in bytes of each file block.
+
+blocks
+st_blocks
+     Number of blocks allocated.
+
+atime
+st_atime
+     Time of last access.
+
+mtime
+st_mtime
+     Time of last modification
+
+ctime
+st_ctime
+     Time of last status change
+
+sparse
+     A boolean value indicating whether the file is `sparse'.
+
+   Modification times are displayed in UTC as UNIX timestamps, unless
+suffixed with `H' (for "human-readable"), as in `ctimeH', in which case
+usual `tar tv' output format is used.
+
+   The default output format is: `name,dev,ino,mode,
+nlink,uid,gid,size,blksize,blocks,atime,mtime,ctime'.
+
+   For example, the following command will display file names and
+corresponding times of last access for each file in the current working
+directory:
+
+     genfile --stat=name,atime *
+
+
+File: tar.info,  Node: Exec Mode,  Prev: Status Mode,  Up: Genfile
+
+D.3 Exec Mode
+=============
+
+This mode is designed for testing the behavior of `paxutils' commands
+when some of the files change during archiving. It is an experimental
+mode.
+
+   The `Exec Mode' is toggled by `--run' command line option (or its
+alias `-r'). The argument to this option gives the command line to be
+executed. The actual command line is constructed by inserting
+`--checkpoint' option between the command name and its first argument
+(if any). Due to this, the argument to `--run' may not use traditional
+`tar' option syntax, i.e., the following is wrong:
+
+     # Wrong!
+     genfile --run 'tar cf foo bar'
+
+Use the following syntax instead:
+
+     genfile --run 'tar -cf foo bar'
+
+   The rest of command line after `--run' or its equivalent specifies
+checkpoint values and actions to be executed upon reaching them.
+Checkpoint values are introduced with `--checkpoint' command line
+option. Argument to this option is the number of checkpoint in decimal.
+
+   Any number of "actions" may be specified after a checkpoint.
+Available actions are
+
+`--cut FILE'
+`--truncate FILE'
+     Truncate FILE to the size specified by previous `--length' option
+     (or 0, if it is not given).
+
+`--append FILE'
+     Append data to FILE. The size of data and its pattern are given by
+     previous `--length' and `pattern' options.
+
+`--touch FILE'
+     Update the access and modification times of FILE. These timestamps
+     are changed to the current time, unless `--date' option was given,
+     in which case they are changed to the specified time. Argument to
+     `--date' option is a date specification in an almost arbitrary
+     format (*note Date input formats::).
+
+`--exec COMMAND'
+     Execute given shell command.
+
+
+   Option `--verbose' instructs `genfile' to print on standard output
+notifications about checkpoints being executed and to verbosely
+describe exit status of the command.
+
+   While the command is being executed its standard output remains
+connected to descriptor 1. All messages it prints to file descriptor 2,
+except checkpoint notifications, are forwarded to standard error.
+
+   `Genfile' exits with the exit status of the executed command.
+
+
+File: tar.info,  Node: Free Software Needs Free Documentation,  Next: Copying This Manual,  Prev: Genfile,  Up: Top
+
+Appendix E Free Software Needs Free Documentation
+*************************************************
+
+The biggest deficiency in the free software community today is not in
+the software--it is the lack of good free documentation that we can
+include with the free software.  Many of our most important programs do
+not come with free reference manuals and free introductory texts.
+Documentation is an essential part of any software package; when an
+important free software package does not come with a free manual and a
+free tutorial, that is a major gap.  We have many such gaps today.
+
+   Consider Perl, for instance.  The tutorial manuals that people
+normally use are non-free.  How did this come about?  Because the
+authors of those manuals published them with restrictive terms--no
+copying, no modification, source files not available--which exclude
+them from the free software world.
+
+   That wasn't the first time this sort of thing happened, and it was
+far from the last.  Many times we have heard a GNU user eagerly
+describe a manual that he is writing, his intended contribution to the
+community, only to learn that he had ruined everything by signing a
+publication contract to make it non-free.
+
+   Free documentation, like free software, is a matter of freedom, not
+price.  The problem with the non-free manual is not that publishers
+charge a price for printed copies--that in itself is fine.  (The Free
+Software Foundation sells printed copies of manuals, too.)  The problem
+is the restrictions on the use of the manual.  Free manuals are
+available in source code form, and give you permission to copy and
+modify.  Non-free manuals do not allow this.
+
+   The criteria of freedom for a free manual are roughly the same as for
+free software.  Redistribution (including the normal kinds of
+commercial redistribution) must be permitted, so that the manual can
+accompany every copy of the program, both on-line and on paper.
+
+   Permission for modification of the technical content is crucial too.
+When people modify the software, adding or changing features, if they
+are conscientious they will change the manual too--so they can provide
+accurate and clear documentation for the modified program.  A manual
+that leaves you no choice but to write a new manual to document a
+changed version of the program is not really available to our community.
+
+   Some kinds of limits on the way modification is handled are
+acceptable.  For example, requirements to preserve the original
+author's copyright notice, the distribution terms, or the list of
+authors, are ok.  It is also no problem to require modified versions to
+include notice that they were modified.  Even entire sections that may
+not be deleted or changed are acceptable, as long as they deal with
+nontechnical topics (like this one).  These kinds of restrictions are
+acceptable because they don't obstruct the community's normal use of
+the manual.
+
+   However, it must be possible to modify all the _technical_ content
+of the manual, and then distribute the result in all the usual media,
+through all the usual channels.  Otherwise, the restrictions obstruct
+the use of the manual, it is not free, and we need another manual to
+replace it.
+
+   Please spread the word about this issue.  Our community continues to
+lose manuals to proprietary publishing.  If we spread the word that
+free software needs free reference manuals and free tutorials, perhaps
+the next person who wants to contribute by writing documentation will
+realize, before it is too late, that only free manuals contribute to
+the free software community.
+
+   If you are writing documentation, please insist on publishing it
+under the GNU Free Documentation License or another free documentation
+license.  Remember that this decision requires your approval--you don't
+have to let the publisher decide.  Some commercial publishers will use
+a free license if you insist, but they will not propose the option; it
+is up to you to raise the issue and say firmly that this is what you
+want.  If the publisher you are dealing with refuses, please try other
+publishers.  If you're not sure whether a proposed license is free,
+write to <licensing@gnu.org>.
+
+   You can encourage commercial publishers to sell more free, copylefted
+manuals and tutorials by buying them, and particularly by buying copies
+from the publishers that paid for their writing or for major
+improvements.  Meanwhile, try to avoid buying non-free documentation at
+all.  Check the distribution terms of a manual before you buy it, and
+insist that whoever seeks your business must respect your freedom.
+Check the history of the book, and try reward the publishers that have
+paid or pay the authors to work on it.
+
+   The Free Software Foundation maintains a list of free documentation
+published by other publishers, at
+`http://www.fsf.org/doc/other-free-books.html'.
+
+
+File: tar.info,  Node: Copying This Manual,  Next: Index of Command Line Options,  Prev: Free Software Needs Free Documentation,  Up: Top
+
+Appendix F Copying This Manual
+******************************
+
+* Menu:
+
+* GNU Free Documentation License::  License for copying this manual
+
+
+File: tar.info,  Node: GNU Free Documentation License,  Up: Copying This Manual
+
+F.1 GNU Free Documentation License
+==================================
+
+                      Version 1.2, November 2002
+
+     Copyright (C) 2000,2001,2002 Free Software Foundation, Inc.
+     51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA
+
+     Everyone is permitted to copy and distribute verbatim copies
+     of this license document, but changing it is not allowed.
+
+  0. PREAMBLE
+
+     The purpose of this License is to make a manual, textbook, or other
+     functional and useful document "free" in the sense of freedom: to
+     assure everyone the effective freedom to copy and redistribute it,
+     with or without modifying it, either commercially or
+     noncommercially.  Secondarily, this License preserves for the
+     author and publisher a way to get credit for their work, while not
+     being considered responsible for modifications made by others.
+
+     This License is a kind of "copyleft", which means that derivative
+     works of the document must themselves be free in the same sense.
+     It complements the GNU General Public License, which is a copyleft
+     license designed for free software.
+
+     We have designed this License in order to use it for manuals for
+     free software, because free software needs free documentation: a
+     free program should come with manuals providing the same freedoms
+     that the software does.  But this License is not limited to
+     software manuals; it can be used for any textual work, regardless
+     of subject matter or whether it is published as a printed book.
+     We recommend this License principally for works whose purpose is
+     instruction or reference.
+
+  1. APPLICABILITY AND DEFINITIONS
+
+     This License applies to any manual or other work, in any medium,
+     that contains a notice placed by the copyright holder saying it
+     can be distributed under the terms of this License.  Such a notice
+     grants a world-wide, royalty-free license, unlimited in duration,
+     to use that work under the conditions stated herein.  The
+     "Document", below, refers to any such manual or work.  Any member
+     of the public is a licensee, and is addressed as "you".  You
+     accept the license if you copy, modify or distribute the work in a
+     way requiring permission under copyright law.
+
+     A "Modified Version" of the Document means any work containing the
+     Document or a portion of it, either copied verbatim, or with
+     modifications and/or translated into another language.
+
+     A "Secondary Section" is a named appendix or a front-matter section
+     of the Document that deals exclusively with the relationship of the
+     publishers or authors of the Document to the Document's overall
+     subject (or to related matters) and contains nothing that could
+     fall directly within that overall subject.  (Thus, if the Document
+     is in part a textbook of mathematics, a Secondary Section may not
+     explain any mathematics.)  The relationship could be a matter of
+     historical connection with the subject or with related matters, or
+     of legal, commercial, philosophical, ethical or political position
+     regarding them.
+
+     The "Invariant Sections" are certain Secondary Sections whose
+     titles are designated, as being those of Invariant Sections, in
+     the notice that says that the Document is released under this
+     License.  If a section does not fit the above definition of
+     Secondary then it is not allowed to be designated as Invariant.
+     The Document may contain zero Invariant Sections.  If the Document
+     does not identify any Invariant Sections then there are none.
+
+     The "Cover Texts" are certain short passages of text that are
+     listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+     that says that the Document is released under this License.  A
+     Front-Cover Text may be at most 5 words, and a Back-Cover Text may
+     be at most 25 words.
+
+     A "Transparent" copy of the Document means a machine-readable copy,
+     represented in a format whose specification is available to the
+     general public, that is suitable for revising the document
+     straightforwardly with generic text editors or (for images
+     composed of pixels) generic paint programs or (for drawings) some
+     widely available drawing editor, and that is suitable for input to
+     text formatters or for automatic translation to a variety of
+     formats suitable for input to text formatters.  A copy made in an
+     otherwise Transparent file format whose markup, or absence of
+     markup, has been arranged to thwart or discourage subsequent
+     modification by readers is not Transparent.  An image format is
+     not Transparent if used for any substantial amount of text.  A
+     copy that is not "Transparent" is called "Opaque".
+
+     Examples of suitable formats for Transparent copies include plain
+     ASCII without markup, Texinfo input format, LaTeX input format,
+     SGML or XML using a publicly available DTD, and
+     standard-conforming simple HTML, PostScript or PDF designed for
+     human modification.  Examples of transparent image formats include
+     PNG, XCF and JPG.  Opaque formats include proprietary formats that
+     can be read and edited only by proprietary word processors, SGML or
+     XML for which the DTD and/or processing tools are not generally
+     available, and the machine-generated HTML, PostScript or PDF
+     produced by some word processors for output purposes only.
+
+     The "Title Page" means, for a printed book, the title page itself,
+     plus such following pages as are needed to hold, legibly, the
+     material this License requires to appear in the title page.  For
+     works in formats which do not have any title page as such, "Title
+     Page" means the text near the most prominent appearance of the
+     work's title, preceding the beginning of the body of the text.
+
+     A section "Entitled XYZ" means a named subunit of the Document
+     whose title either is precisely XYZ or contains XYZ in parentheses
+     following text that translates XYZ in another language.  (Here XYZ
+     stands for a specific section name mentioned below, such as
+     "Acknowledgements", "Dedications", "Endorsements", or "History".)
+     To "Preserve the Title" of such a section when you modify the
+     Document means that it remains a section "Entitled XYZ" according
+     to this definition.
+
+     The Document may include Warranty Disclaimers next to the notice
+     which states that this License applies to the Document.  These
+     Warranty Disclaimers are considered to be included by reference in
+     this License, but only as regards disclaiming warranties: any other
+     implication that these Warranty Disclaimers may have is void and
+     has no effect on the meaning of this License.
+
+  2. VERBATIM COPYING
+
+     You may copy and distribute the Document in any medium, either
+     commercially or noncommercially, provided that this License, the
+     copyright notices, and the license notice saying this License
+     applies to the Document are reproduced in all copies, and that you
+     add no other conditions whatsoever to those of this License.  You
+     may not use technical measures to obstruct or control the reading
+     or further copying of the copies you make or distribute.  However,
+     you may accept compensation in exchange for copies.  If you
+     distribute a large enough number of copies you must also follow
+     the conditions in section 3.
+
+     You may also lend copies, under the same conditions stated above,
+     and you may publicly display copies.
+
+  3. COPYING IN QUANTITY
+
+     If you publish printed copies (or copies in media that commonly
+     have printed covers) of the Document, numbering more than 100, and
+     the Document's license notice requires Cover Texts, you must
+     enclose the copies in covers that carry, clearly and legibly, all
+     these Cover Texts: Front-Cover Texts on the front cover, and
+     Back-Cover Texts on the back cover.  Both covers must also clearly
+     and legibly identify you as the publisher of these copies.  The
+     front cover must present the full title with all words of the
+     title equally prominent and visible.  You may add other material
+     on the covers in addition.  Copying with changes limited to the
+     covers, as long as they preserve the title of the Document and
+     satisfy these conditions, can be treated as verbatim copying in
+     other respects.
+
+     If the required texts for either cover are too voluminous to fit
+     legibly, you should put the first ones listed (as many as fit
+     reasonably) on the actual cover, and continue the rest onto
+     adjacent pages.
+
+     If you publish or distribute Opaque copies of the Document
+     numbering more than 100, you must either include a
+     machine-readable Transparent copy along with each Opaque copy, or
+     state in or with each Opaque copy a computer-network location from
+     which the general network-using public has access to download
+     using public-standard network protocols a complete Transparent
+     copy of the Document, free of added material.  If you use the
+     latter option, you must take reasonably prudent steps, when you
+     begin distribution of Opaque copies in quantity, to ensure that
+     this Transparent copy will remain thus accessible at the stated
+     location until at least one year after the last time you
+     distribute an Opaque copy (directly or through your agents or
+     retailers) of that edition to the public.
+
+     It is requested, but not required, that you contact the authors of
+     the Document well before redistributing any large number of
+     copies, to give them a chance to provide you with an updated
+     version of the Document.
+
+  4. MODIFICATIONS
+
+     You may copy and distribute a Modified Version of the Document
+     under the conditions of sections 2 and 3 above, provided that you
+     release the Modified Version under precisely this License, with
+     the Modified Version filling the role of the Document, thus
+     licensing distribution and modification of the Modified Version to
+     whoever possesses a copy of it.  In addition, you must do these
+     things in the Modified Version:
+
+       A. Use in the Title Page (and on the covers, if any) a title
+          distinct from that of the Document, and from those of
+          previous versions (which should, if there were any, be listed
+          in the History section of the Document).  You may use the
+          same title as a previous version if the original publisher of
+          that version gives permission.
+
+       B. List on the Title Page, as authors, one or more persons or
+          entities responsible for authorship of the modifications in
+          the Modified Version, together with at least five of the
+          principal authors of the Document (all of its principal
+          authors, if it has fewer than five), unless they release you
+          from this requirement.
+
+       C. State on the Title page the name of the publisher of the
+          Modified Version, as the publisher.
+
+       D. Preserve all the copyright notices of the Document.
+
+       E. Add an appropriate copyright notice for your modifications
+          adjacent to the other copyright notices.
+
+       F. Include, immediately after the copyright notices, a license
+          notice giving the public permission to use the Modified
+          Version under the terms of this License, in the form shown in
+          the Addendum below.
+
+       G. Preserve in that license notice the full lists of Invariant
+          Sections and required Cover Texts given in the Document's
+          license notice.
+
+       H. Include an unaltered copy of this License.
+
+       I. Preserve the section Entitled "History", Preserve its Title,
+          and add to it an item stating at least the title, year, new
+          authors, and publisher of the Modified Version as given on
+          the Title Page.  If there is no section Entitled "History" in
+          the Document, create one stating the title, year, authors,
+          and publisher of the Document as given on its Title Page,
+          then add an item describing the Modified Version as stated in
+          the previous sentence.
+
+       J. Preserve the network location, if any, given in the Document
+          for public access to a Transparent copy of the Document, and
+          likewise the network locations given in the Document for
+          previous versions it was based on.  These may be placed in
+          the "History" section.  You may omit a network location for a
+          work that was published at least four years before the
+          Document itself, or if the original publisher of the version
+          it refers to gives permission.
+
+       K. For any section Entitled "Acknowledgements" or "Dedications",
+          Preserve the Title of the section, and preserve in the
+          section all the substance and tone of each of the contributor
+          acknowledgements and/or dedications given therein.
+
+       L. Preserve all the Invariant Sections of the Document,
+          unaltered in their text and in their titles.  Section numbers
+          or the equivalent are not considered part of the section
+          titles.
+
+       M. Delete any section Entitled "Endorsements".  Such a section
+          may not be included in the Modified Version.
+
+       N. Do not retitle any existing section to be Entitled
+          "Endorsements" or to conflict in title with any Invariant
+          Section.
+
+       O. Preserve any Warranty Disclaimers.
+
+     If the Modified Version includes new front-matter sections or
+     appendices that qualify as Secondary Sections and contain no
+     material copied from the Document, you may at your option
+     designate some or all of these sections as invariant.  To do this,
+     add their titles to the list of Invariant Sections in the Modified
+     Version's license notice.  These titles must be distinct from any
+     other section titles.
+
+     You may add a section Entitled "Endorsements", provided it contains
+     nothing but endorsements of your Modified Version by various
+     parties--for example, statements of peer review or that the text
+     has been approved by an organization as the authoritative
+     definition of a standard.
+
+     You may add a passage of up to five words as a Front-Cover Text,
+     and a passage of up to 25 words as a Back-Cover Text, to the end
+     of the list of Cover Texts in the Modified Version.  Only one
+     passage of Front-Cover Text and one of Back-Cover Text may be
+     added by (or through arrangements made by) any one entity.  If the
+     Document already includes a cover text for the same cover,
+     previously added by you or by arrangement made by the same entity
+     you are acting on behalf of, you may not add another; but you may
+     replace the old one, on explicit permission from the previous
+     publisher that added the old one.
+
+     The author(s) and publisher(s) of the Document do not by this
+     License give permission to use their names for publicity for or to
+     assert or imply endorsement of any Modified Version.
+
+  5. COMBINING DOCUMENTS
+
+     You may combine the Document with other documents released under
+     this License, under the terms defined in section 4 above for
+     modified versions, provided that you include in the combination
+     all of the Invariant Sections of all of the original documents,
+     unmodified, and list them all as Invariant Sections of your
+     combined work in its license notice, and that you preserve all
+     their Warranty Disclaimers.
+
+     The combined work need only contain one copy of this License, and
+     multiple identical Invariant Sections may be replaced with a single
+     copy.  If there are multiple Invariant Sections with the same name
+     but different contents, make the title of each such section unique
+     by adding at the end of it, in parentheses, the name of the
+     original author or publisher of that section if known, or else a
+     unique number.  Make the same adjustment to the section titles in
+     the list of Invariant Sections in the license notice of the
+     combined work.
+
+     In the combination, you must combine any sections Entitled
+     "History" in the various original documents, forming one section
+     Entitled "History"; likewise combine any sections Entitled
+     "Acknowledgements", and any sections Entitled "Dedications".  You
+     must delete all sections Entitled "Endorsements."
+
+  6. COLLECTIONS OF DOCUMENTS
+
+     You may make a collection consisting of the Document and other
+     documents released under this License, and replace the individual
+     copies of this License in the various documents with a single copy
+     that is included in the collection, provided that you follow the
+     rules of this License for verbatim copying of each of the
+     documents in all other respects.
+
+     You may extract a single document from such a collection, and
+     distribute it individually under this License, provided you insert
+     a copy of this License into the extracted document, and follow
+     this License in all other respects regarding verbatim copying of
+     that document.
+
+  7. AGGREGATION WITH INDEPENDENT WORKS
+
+     A compilation of the Document or its derivatives with other
+     separate and independent documents or works, in or on a volume of
+     a storage or distribution medium, is called an "aggregate" if the
+     copyright resulting from the compilation is not used to limit the
+     legal rights of the compilation's users beyond what the individual
+     works permit.  When the Document is included in an aggregate, this
+     License does not apply to the other works in the aggregate which
+     are not themselves derivative works of the Document.
+
+     If the Cover Text requirement of section 3 is applicable to these
+     copies of the Document, then if the Document is less than one half
+     of the entire aggregate, the Document's Cover Texts may be placed
+     on covers that bracket the Document within the aggregate, or the
+     electronic equivalent of covers if the Document is in electronic
+     form.  Otherwise they must appear on printed covers that bracket
+     the whole aggregate.
+
+  8. TRANSLATION
+
+     Translation is considered a kind of modification, so you may
+     distribute translations of the Document under the terms of section
+     4.  Replacing Invariant Sections with translations requires special
+     permission from their copyright holders, but you may include
+     translations of some or all Invariant Sections in addition to the
+     original versions of these Invariant Sections.  You may include a
+     translation of this License, and all the license notices in the
+     Document, and any Warranty Disclaimers, provided that you also
+     include the original English version of this License and the
+     original versions of those notices and disclaimers.  In case of a
+     disagreement between the translation and the original version of
+     this License or a notice or disclaimer, the original version will
+     prevail.
+
+     If a section in the Document is Entitled "Acknowledgements",
+     "Dedications", or "History", the requirement (section 4) to
+     Preserve its Title (section 1) will typically require changing the
+     actual title.
+
+  9. TERMINATION
+
+     You may not copy, modify, sublicense, or distribute the Document
+     except as expressly provided for under this License.  Any other
+     attempt to copy, modify, sublicense or distribute the Document is
+     void, and will automatically terminate your rights under this
+     License.  However, parties who have received copies, or rights,
+     from you under this License will not have their licenses
+     terminated so long as such parties remain in full compliance.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+     The Free Software Foundation may publish new, revised versions of
+     the GNU Free Documentation License from time to time.  Such new
+     versions will be similar in spirit to the present version, but may
+     differ in detail to address new problems or concerns.  See
+     `http://www.gnu.org/copyleft/'.
+
+     Each version of the License is given a distinguishing version
+     number.  If the Document specifies that a particular numbered
+     version of this License "or any later version" applies to it, you
+     have the option of following the terms and conditions either of
+     that specified version or of any later version that has been
+     published (not as a draft) by the Free Software Foundation.  If
+     the Document does not specify a version number of this License,
+     you may choose any version ever published (not as a draft) by the
+     Free Software Foundation.
+
+F.1.1 ADDENDUM: How to use this License for your documents
+----------------------------------------------------------
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+       Copyright (C)  YEAR  YOUR NAME.
+       Permission is granted to copy, distribute and/or modify this document
+       under the terms of the GNU Free Documentation License, Version 1.2
+       or any later version published by the Free Software Foundation;
+       with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
+       Texts.  A copy of the license is included in the section entitled ``GNU
+       Free Documentation License''.
+
+   If you have Invariant Sections, Front-Cover Texts and Back-Cover
+Texts, replace the "with...Texts." line with this:
+
+         with the Invariant Sections being LIST THEIR TITLES, with
+         the Front-Cover Texts being LIST, and with the Back-Cover Texts
+         being LIST.
+
+   If you have Invariant Sections without Cover Texts, or some other
+combination of the three, merge those two alternatives to suit the
+situation.
+
+   If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License, to
+permit their use in free software.
+
+
+File: tar.info,  Node: Index of Command Line Options,  Next: Index,  Prev: Copying This Manual,  Up: Top
+
+Appendix G Index of Command Line Options
+****************************************
+
+This appendix contains an index of all GNU `tar' long command line
+options. The options are listed without the preceding double-dash.  For
+a cross-reference of short command line options, *note Short Option
+Summary::.
+
+
+* Menu:
+
+* absolute-names:                        absolute.            (line   8)
+* absolute-names, summary:               Option Summary.      (line   6)
+* add-file:                              files.               (line  84)
+* after-date:                            after.               (line  26)
+* after-date, summary:                   Option Summary.      (line  12)
+* anchored:                              controlling pattern-matching.
+                                                              (line  79)
+* anchored, summary:                     Option Summary.      (line  15)
+* append:                                append.              (line   8)
+* append, summary:                       Operation Summary.   (line   6)
+* atime-preserve:                        Attributes.          (line  14)
+* atime-preserve, summary:               Option Summary.      (line  19)
+* backup:                                backup.              (line  41)
+* backup, summary:                       Option Summary.      (line  65)
+* block-number:                          verbose.             (line 111)
+* block-number, summary:                 Option Summary.      (line  70)
+* blocking-factor:                       Blocking Factor.     (line   8)
+* blocking-factor, summary:              Option Summary.      (line  76)
+* bzip2:                                 gzip.                (line  88)
+* bzip2, summary:                        Option Summary.      (line  81)
+* catenate:                              concatenate.         (line   6)
+* catenate, summary:                     Operation Summary.   (line  10)
+* check-links, summary:                  Option Summary.      (line  93)
+* checkpoint:                            verbose.             (line  83)
+* checkpoint, summary:                   Option Summary.      (line  86)
+* compare:                               compare.             (line   8)
+* compare, summary:                      Operation Summary.   (line  14)
+* compress:                              gzip.                (line  92)
+* compress, summary:                     Option Summary.      (line 100)
+* concatenate:                           concatenate.         (line   6)
+* concatenate, summary:                  Operation Summary.   (line  20)
+* confirmation, summary:                 Option Summary.      (line 107)
+* create, additional options:            create options.      (line   6)
+* create, complementary notes:           Basic tar.           (line  11)
+* create, introduced:                    Creating the archive.
+                                                              (line   6)
+* create, summary:                       Operation Summary.   (line  25)
+* create, using with --verbose:          create verbose.      (line   6)
+* create, using with --verify:           verify.              (line  24)
+* delay-directory-restore:               Directory Modification Times and Permissions.
+                                                              (line  62)
+* delay-directory-restore, summary:      Option Summary.      (line 110)
+* delete:                                delete.              (line   8)
+* delete, summary:                       Operation Summary.   (line  29)
+* dereference:                           dereference.         (line   6)
+* dereference, summary:                  Option Summary.      (line 115)
+* diff, summary:                         Operation Summary.   (line  33)
+* directory:                             directory.           (line  11)
+* directory, summary:                    Option Summary.      (line 121)
+* directory, using in --files-from argument: files.           (line  60)
+* exclude:                               exclude.             (line  11)
+* exclude, potential problems with:      problems with exclude.
+                                                              (line   6)
+* exclude, summary:                      Option Summary.      (line 128)
+* exclude-caches:                        exclude.             (line  45)
+* exclude-caches, summary:               Option Summary.      (line 137)
+* exclude-caches-all:                    exclude.             (line  53)
+* exclude-caches-all, summary:           Option Summary.      (line 150)
+* exclude-caches-under:                  exclude.             (line  49)
+* exclude-caches-under, summary:         Option Summary.      (line 144)
+* exclude-from:                          exclude.             (line  22)
+* exclude-from, summary:                 Option Summary.      (line 132)
+* exclude-tag:                           exclude.             (line  62)
+* exclude-tag, summary:                  Option Summary.      (line 154)
+* exclude-tag-all:                       exclude.             (line  70)
+* exclude-tag-all, summary:              Option Summary.      (line 162)
+* exclude-tag-under:                     exclude.             (line  66)
+* exclude-tag-under, summary:            Option Summary.      (line 158)
+* extract:                               extract.             (line   8)
+* extract, additional options:           extract options.     (line   8)
+* extract, complementary notes:          Basic tar.           (line  48)
+* extract, summary:                      Operation Summary.   (line  37)
+* extract, using with --listed-incremental: Incremental Dumps.
+                                                              (line  93)
+* file, short description:               file.                (line  17)
+* file, summary:                         Option Summary.      (line 166)
+* file, tutorial:                        file tutorial.       (line   6)
+* files-from:                            files.               (line  14)
+* files-from, summary:                   Option Summary.      (line 172)
+* force-local, short description:        Device.              (line  70)
+* force-local, summary:                  Option Summary.      (line 178)
+* format, summary:                       Option Summary.      (line 183)
+* get, summary:                          Operation Summary.   (line  42)
+* group:                                 override.            (line  73)
+* group, summary:                        Option Summary.      (line 208)
+* gunzip, summary:                       Option Summary.      (line 216)
+* gzip:                                  gzip.                (line  54)
+* gzip, summary:                         Option Summary.      (line 216)
+* help:                                  help tutorial.       (line   6)
+* help, introduction:                    help.                (line  26)
+* help, summary:                         Option Summary.      (line 224)
+* ignore-case:                           controlling pattern-matching.
+                                                              (line  86)
+* ignore-case, summary:                  Option Summary.      (line 229)
+* ignore-command-error:                  Writing to an External Program.
+                                                              (line  82)
+* ignore-command-error, summary:         Option Summary.      (line 233)
+* ignore-failed-read:                    Ignore Failed Read.  (line   7)
+* ignore-failed-read, summary:           Option Summary.      (line 237)
+* ignore-zeros:                          Ignore Zeros.        (line   6)
+* ignore-zeros, short description:       Blocking Factor.     (line 156)
+* ignore-zeros, summary:                 Option Summary.      (line 241)
+* incremental, summary:                  Option Summary.      (line 246)
+* incremental, using with --list:        Incremental Dumps.   (line 158)
+* index-file, summary:                   Option Summary.      (line 253)
+* info-script:                           Multi-Volume Archives.
+                                                              (line  80)
+* info-script, short description:        Device.              (line 104)
+* info-script, summary:                  Option Summary.      (line 256)
+* interactive:                           interactive.         (line  14)
+* interactive, summary:                  Option Summary.      (line 264)
+* keep-newer-files:                      Keep Newer Files.    (line   6)
+* keep-newer-files, summary:             Option Summary.      (line 271)
+* keep-old-files:                        Keep Old Files.      (line   6)
+* keep-old-files, introduced:            Dealing with Old Files.
+                                                              (line  16)
+* keep-old-files, summary:               Option Summary.      (line 275)
+* label:                                 label.               (line   8)
+* label, summary:                        Option Summary.      (line 280)
+* list:                                  list.                (line   6)
+* list, summary:                         Operation Summary.   (line  46)
+* list, using with --incremental:        Incremental Dumps.   (line 158)
+* list, using with --listed-incremental: Incremental Dumps.   (line 158)
+* list, using with --verbose:            list.                (line  30)
+* list, using with file name arguments:  list.                (line  68)
+* listed-incremental:                    Incremental Dumps.   (line  14)
+* listed-incremental, summary:           Option Summary.      (line 287)
+* listed-incremental, using with --extract: Incremental Dumps.
+                                                              (line  93)
+* listed-incremental, using with --list: Incremental Dumps.   (line 158)
+* mode:                                  override.            (line  14)
+* mode, summary:                         Option Summary.      (line 295)
+* mtime:                                 override.            (line  29)
+* mtime, summary:                        Option Summary.      (line 301)
+* multi-volume:                          Multi-Volume Archives.
+                                                              (line   6)
+* multi-volume, short description:       Device.              (line  88)
+* multi-volume, summary:                 Option Summary.      (line 310)
+* new-volume-script:                     Multi-Volume Archives.
+                                                              (line  80)
+* new-volume-script, short description:  Device.              (line 104)
+* new-volume-script, summary:            Option Summary.      (line 256)
+* newer:                                 after.               (line  26)
+* newer, summary:                        Option Summary.      (line 318)
+* newer-mtime:                           after.               (line  37)
+* newer-mtime, summary:                  Option Summary.      (line 326)
+* no-anchored:                           controlling pattern-matching.
+                                                              (line  79)
+* no-anchored, summary:                  Option Summary.      (line 331)
+* no-delay-directory-restore:            Directory Modification Times and Permissions.
+                                                              (line  68)
+* no-delay-directory-restore, summary:   Option Summary.      (line 335)
+* no-ignore-case:                        controlling pattern-matching.
+                                                              (line  86)
+* no-ignore-case, summary:               Option Summary.      (line 341)
+* no-ignore-command-error:               Writing to an External Program.
+                                                              (line  87)
+* no-ignore-command-error, summary:      Option Summary.      (line 344)
+* no-overwrite-dir, summary:             Option Summary.      (line 348)
+* no-quote-chars, summary:               Option Summary.      (line 352)
+* no-recursion:                          recurse.             (line  13)
+* no-recursion, summary:                 Option Summary.      (line 357)
+* no-same-owner:                         Attributes.          (line  67)
+* no-same-owner, summary:                Option Summary.      (line 361)
+* no-same-permissions, summary:          Option Summary.      (line 367)
+* no-unquote:                            Selecting Archive Members.
+                                                              (line  42)
+* no-unquote, summary:                   Option Summary.      (line 372)
+* no-wildcards:                          controlling pattern-matching.
+                                                              (line  41)
+* no-wildcards, summary:                 Option Summary.      (line 376)
+* no-wildcards-match-slash:              controlling pattern-matching.
+                                                              (line  92)
+* no-wildcards-match-slash, summary:     Option Summary.      (line 379)
+* null:                                  nul.                 (line  11)
+* null, summary:                         Option Summary.      (line 382)
+* numeric-owner:                         Attributes.          (line  73)
+* numeric-owner, summary:                Option Summary.      (line 388)
+* occurrence, summary:                   Option Summary.      (line 405)
+* old-archive, summary:                  Option Summary.      (line 419)
+* one-file-system:                       one.                 (line  16)
+* one-file-system, summary:              Option Summary.      (line 422)
+* overwrite:                             Overwrite Old Files. (line   6)
+* overwrite, introduced:                 Dealing with Old Files.
+                                                              (line  22)
+* overwrite, summary:                    Option Summary.      (line 427)
+* overwrite-dir:                         Overwrite Old Files. (line  28)
+* overwrite-dir, introduced:             Dealing with Old Files.
+                                                              (line   6)
+* overwrite-dir, summary:                Option Summary.      (line 431)
+* owner:                                 override.            (line  57)
+* owner, summary:                        Option Summary.      (line 435)
+* pax-option:                            PAX keywords.        (line   6)
+* pax-option, summary:                   Option Summary.      (line 444)
+* portability, summary:                  Option Summary.      (line 450)
+* posix, summary:                        Option Summary.      (line 454)
+* preserve:                              Attributes.          (line 126)
+* preserve, summary:                     Option Summary.      (line 457)
+* preserve-order:                        Same Order.          (line   6)
+* preserve-order, summary:               Option Summary.      (line 461)
+* preserve-permissions:                  Setting Access Permissions.
+                                                              (line  10)
+* preserve-permissions, short description: Attributes.        (line 113)
+* preserve-permissions, summary:         Option Summary.      (line 464)
+* quote-chars, summary:                  Option Summary.      (line 474)
+* quoting-style:                         quoting styles.      (line  39)
+* quoting-style, summary:                Option Summary.      (line 478)
+* read-full-records <1>:                 read full records.   (line   6)
+* read-full-records:                     Reading.             (line   8)
+* read-full-records, short description:  Blocking Factor.     (line 172)
+* read-full-records, summary:            Option Summary.      (line 485)
+* record-size, summary:                  Option Summary.      (line 490)
+* recursion:                             recurse.             (line  24)
+* recursion, summary:                    Option Summary.      (line 494)
+* recursive-unlink:                      Recursive Unlink.    (line   6)
+* recursive-unlink, summary:             Option Summary.      (line 498)
+* remove-files:                          remove files.        (line   6)
+* remove-files, summary:                 Option Summary.      (line 503)
+* restrict, summary:                     Option Summary.      (line 507)
+* rmt-command, summary:                  Option Summary.      (line 512)
+* rsh-command:                           Device.              (line  73)
+* rsh-command, summary:                  Option Summary.      (line 516)
+* same-order:                            Same Order.          (line   6)
+* same-order, summary:                   Option Summary.      (line 520)
+* same-owner:                            Attributes.          (line  48)
+* same-owner, summary:                   Option Summary.      (line 528)
+* same-permissions:                      Setting Access Permissions.
+                                                              (line  10)
+* same-permissions, short description:   Attributes.          (line 113)
+* same-permissions, summary:             Option Summary.      (line 464)
+* seek, summary:                         Option Summary.      (line 537)
+* show-defaults:                         defaults.            (line   6)
+* show-defaults, summary:                Option Summary.      (line 544)
+* show-omitted-dirs:                     verbose.             (line 103)
+* show-omitted-dirs, summary:            Option Summary.      (line 553)
+* show-stored-names:                     list.                (line  60)
+* show-stored-names, summary:            Option Summary.      (line 557)
+* show-transformed-names:                transform.           (line  45)
+* show-transformed-names, summary:       Option Summary.      (line 557)
+* sparse:                                sparse.              (line  22)
+* sparse, summary:                       Option Summary.      (line 565)
+* sparse-version:                        sparse.              (line  57)
+* sparse-version, summary:               Option Summary.      (line 570)
+* starting-file:                         Starting File.       (line   6)
+* starting-file, summary:                Option Summary.      (line 575)
+* strip-components:                      transform.           (line  25)
+* strip-components, summary:             Option Summary.      (line 581)
+* suffix:                                backup.              (line  68)
+* suffix, summary:                       Option Summary.      (line 590)
+* tape-length:                           Multi-Volume Archives.
+                                                              (line  33)
+* tape-length, short description:        Device.              (line  96)
+* tape-length, summary:                  Option Summary.      (line 596)
+* test-label:                            label.               (line  37)
+* test-label, summary:                   Option Summary.      (line 601)
+* to-command:                            Writing to an External Program.
+                                                              (line   9)
+* to-command, summary:                   Option Summary.      (line 605)
+* to-stdout:                             Writing to Standard Output.
+                                                              (line  14)
+* to-stdout, summary:                    Option Summary.      (line 609)
+* totals:                                verbose.             (line  46)
+* totals, summary:                       Option Summary.      (line 614)
+* touch <1>:                             Attributes.          (line  37)
+* touch:                                 Data Modification Times.
+                                                              (line  15)
+* touch, summary:                        Option Summary.      (line 619)
+* transform:                             transform.           (line  74)
+* transform, summary:                    Option Summary.      (line 625)
+* uncompress:                            gzip.                (line  92)
+* uncompress, summary:                   Option Summary.      (line 100)
+* ungzip:                                gzip.                (line  54)
+* ungzip, summary:                       Option Summary.      (line 216)
+* unlink-first:                          Unlink First.        (line   6)
+* unlink-first, introduced:              Dealing with Old Files.
+                                                              (line  42)
+* unlink-first, summary:                 Option Summary.      (line 644)
+* unquote:                               Selecting Archive Members.
+                                                              (line  39)
+* unquote, summary:                      Option Summary.      (line 650)
+* update:                                update.              (line   8)
+* update, summary:                       Operation Summary.   (line  50)
+* usage:                                 help.                (line  53)
+* use-compress-program:                  gzip.                (line 101)
+* use-compress-program, summary:         Option Summary.      (line 654)
+* utc, summary:                          Option Summary.      (line 658)
+* verbose:                               verbose.             (line  18)
+* verbose, introduced:                   verbose tutorial.    (line   6)
+* verbose, summary:                      Option Summary.      (line 662)
+* verbose, using with --create:          create verbose.      (line   6)
+* verbose, using with --list:            list.                (line  30)
+* verify, short description:             verify.              (line   8)
+* verify, summary:                       Option Summary.      (line 669)
+* verify, using with --create:           verify.              (line  24)
+* version:                               help.                (line   6)
+* version, summary:                      Option Summary.      (line 674)
+* volno-file:                            Multi-Volume Archives.
+                                                              (line  71)
+* volno-file, summary:                   Option Summary.      (line 679)
+* wildcards:                             controlling pattern-matching.
+                                                              (line  38)
+* wildcards, summary:                    Option Summary.      (line 684)
+* wildcards-match-slash:                 controlling pattern-matching.
+                                                              (line  92)
+* wildcards-match-slash, summary:        Option Summary.      (line 688)
+
+
+File: tar.info,  Node: Index,  Prev: Index of Command Line Options,  Up: Top
+
+Appendix H Index
+****************
+
+
+* Menu:
+
+* abbreviations for months:              Calendar date items. (line  38)
+* absolute file names:                   Remote Tape Server.  (line  17)
+* Adding archives to an archive:         concatenate.         (line   6)
+* Adding files to an Archive:            appending files.     (line   8)
+* ADMINISTRATOR:                         General-Purpose Variables.
+                                                              (line   7)
+* Age, excluding files by:               after.               (line   8)
+* ago in date strings:                   Relative items in date strings.
+                                                              (line  23)
+* am in date strings:                    Time of day items.   (line  22)
+* Appending files to an Archive:         appending files.     (line   8)
+* archive:                               Definitions.         (line   6)
+* Archive creation:                      file.                (line  36)
+* archive member:                        Definitions.         (line  15)
+* Archive Name:                          file.                (line   8)
+* Archive, creation of:                  create.              (line   8)
+* Archives, Appending files to:          appending files.     (line   8)
+* Archiving Directories:                 create dir.          (line   6)
+* archiving files:                       Top.                 (line  24)
+* ARGP_HELP_FMT, environment variable:   Configuring Help Summary.
+                                                              (line  22)
+* authors of get_date:                   Authors of get_date. (line   6)
+* Avoiding recursion in directories:     recurse.             (line   8)
+* backup options:                        backup.              (line   6)
+* backup suffix:                         backup.              (line  68)
+* BACKUP_DIRS:                           General-Purpose Variables.
+                                                              (line  29)
+* BACKUP_FILES:                          General-Purpose Variables.
+                                                              (line  55)
+* BACKUP_HOUR:                           General-Purpose Variables.
+                                                              (line  11)
+* backups:                               backup.              (line  41)
+* beginning of time, for POSIX:          Seconds since the Epoch.
+                                                              (line  13)
+* Bellovin, Steven M.:                   Authors of get_date. (line   6)
+* Berets, Jim:                           Authors of get_date. (line   6)
+* Berry, K.:                             Authors of get_date. (line  14)
+* Block number where error occurred:     verbose.             (line 111)
+* BLOCKING:                              General-Purpose Variables.
+                                                              (line  25)
+* blocking factor:                       Blocking Factor.     (line 194)
+* Blocking Factor:                       Blocking Factor.     (line   6)
+* Blocks per record:                     Blocking Factor.     (line   6)
+* bug reports:                           Reports.             (line   6)
+* Bytes per record:                      Blocking Factor.     (line   6)
+* calendar date item:                    Calendar date items. (line   6)
+* case, ignored in dates:                General date syntax. (line  64)
+* cat vs concatenate:                    concatenate.         (line  63)
+* Changing directory mid-stream:         directory.           (line   6)
+* Character class, excluding characters from: wildcards.      (line  34)
+* Choosing an archive file:              file.                (line   8)
+* comments, in dates:                    General date syntax. (line  64)
+* Compressed archives:                   gzip.                (line   6)
+* concatenate vs cat:                    concatenate.         (line  63)
+* Concatenating Archives:                concatenate.         (line   6)
+* corrupted archives <1>:                gzip.                (line  73)
+* corrupted archives:                    Full Dumps.          (line   8)
+* Creation of the archive:               create.              (line   8)
+* DAT blocking:                          Blocking Factor.     (line 204)
+* Data Modification time, excluding files by: after.          (line   8)
+* Data modification times of extracted files: Data Modification Times.
+                                                              (line   6)
+* date format, ISO 8601:                 Calendar date items. (line  30)
+* date input formats:                    Date input formats.  (line   6)
+* day in date strings:                   Relative items in date strings.
+                                                              (line  15)
+* day of week item:                      Day of week items.   (line   6)
+* Deleting files from an archive:        delete.              (line   8)
+* Deleting from tape archives:           delete.              (line  19)
+* Descending directories, avoiding:      recurse.             (line   8)
+* Directories, Archiving:                create dir.          (line   6)
+* Directories, avoiding recursion:       recurse.             (line   8)
+* Directory, changing mid-stream:        directory.           (line   6)
+* DIRLIST:                               General-Purpose Variables.
+                                                              (line  51)
+* displacement of dates:                 Relative items in date strings.
+                                                              (line   6)
+* doc-opt-col:                           Configuring Help Summary.
+                                                              (line  95)
+* Double-checking a write operation:     verify.              (line   6)
+* DUMP_BEGIN:                            User Hooks.          (line  32)
+* DUMP_END:                              User Hooks.          (line  36)
+* DUMP_REMIND_SCRIPT:                    General-Purpose Variables.
+                                                              (line 102)
+* dumps, full:                           Full Dumps.          (line   8)
+* dup-args:                              Configuring Help Summary.
+                                                              (line  52)
+* dup-args-note:                         Configuring Help Summary.
+                                                              (line  69)
+* Eggert, Paul:                          Authors of get_date. (line   6)
+* End-of-archive blocks, ignoring:       Ignore Zeros.        (line   6)
+* End-of-archive info script:            Multi-Volume Archives.
+                                                              (line  80)
+* entry:                                 Naming tar Archives. (line  11)
+* epoch, for POSIX:                      Seconds since the Epoch.
+                                                              (line  13)
+* Error message, block number of:        verbose.             (line 121)
+* Exabyte blocking:                      Blocking Factor.     (line 204)
+* exclude:                               exclude.             (line  14)
+* exclude-caches:                        exclude.             (line  33)
+* exclude-from:                          exclude.             (line  27)
+* exclude-tag:                           exclude.             (line  56)
+* Excluding characters from a character class: wildcards.     (line  34)
+* Excluding file by age:                 after.               (line   8)
+* Excluding files by file system:        exclude.             (line   8)
+* Excluding files by name and pattern:   exclude.             (line   8)
+* Exec Mode, genfile:                    Exec Mode.           (line   6)
+* existing backup method:                backup.              (line  59)
+* exit status:                           Synopsis.            (line  67)
+* Extraction:                            extract.             (line   8)
+* extraction:                            Definitions.         (line  22)
+* FDL, GNU Free Documentation License:   GNU Free Documentation License.
+                                                              (line   6)
+* file archival:                         Top.                 (line  24)
+* File lists separated by NUL characters: Generate Mode.      (line  33)
+* file name:                             Definitions.         (line  15)
+* File Name arguments, alternatives:     files.               (line   6)
+* File name arguments, using --list with: list.               (line  68)
+* File names, excluding files by:        exclude.             (line   8)
+* File names, terminated by NUL:         nul.                 (line   6)
+* File names, using symbolic links:      dereference.         (line   6)
+* File system boundaries, not crossing:  one.                 (line   6)
+* FILELIST:                              General-Purpose Variables.
+                                                              (line  65)
+* first in date strings:                 General date syntax. (line  26)
+* Format Options:                        Format Variations.   (line   6)
+* Format Parameters:                     Format Variations.   (line   6)
+* Format, old style:                     old.                 (line   6)
+* fortnight in date strings:             Relative items in date strings.
+                                                              (line  15)
+* free documentation:                    Free Software Needs Free Documentation.
+                                                              (line   6)
+* full dumps:                            Full Dumps.          (line   8)
+* future time stamps:                    Large or Negative Values.
+                                                              (line   6)
+* general date syntax:                   General date syntax. (line   6)
+* Generate Mode, genfile:                Generate Mode.       (line   6)
+* genfile:                               Genfile.             (line   6)
+* genfile, create file:                  Generate Mode.       (line   6)
+* genfile, creating sparse files:        Generate Mode.       (line  55)
+* genfile, generate mode:                Generate Mode.       (line   6)
+* genfile, reading a list of file names: Generate Mode.       (line  22)
+* genfile, seeking to a given offset:    Generate Mode.       (line  18)
+* get_date:                              Date input formats.  (line   6)
+* Getting program version number:        help.                (line   6)
+* GNU archive format:                    gnu.                 (line   6)
+* GNU.sparse.major, extended header variable: PAX 1.          (line  14)
+* GNU.sparse.map, extended header variable: PAX 0.            (line  60)
+* GNU.sparse.minor, extended header variable: PAX 1.          (line  17)
+* GNU.sparse.name, extended header variable: PAX 0.           (line  68)
+* GNU.sparse.name, extended header variable, in v.1.0: PAX 1. (line  24)
+* GNU.sparse.numblocks, extended header variable: PAX 0.      (line  15)
+* GNU.sparse.numbytes, extended header variable: PAX 0.       (line  21)
+* GNU.sparse.offset, extended header variable: PAX 0.         (line  18)
+* GNU.sparse.realsize, extended header variable: PAX 1.       (line  24)
+* GNU.sparse.size, extended header variable: PAX 0.           (line  11)
+* gnupg, using with tar:                 gzip.                (line 113)
+* gpg, using with tar:                   gzip.                (line 113)
+* header-col:                            Configuring Help Summary.
+                                                              (line 141)
+* hook:                                  User Hooks.          (line  13)
+* hour in date strings:                  Relative items in date strings.
+                                                              (line  15)
+* Ignoring end-of-archive blocks:        Ignore Zeros.        (line   6)
+* Info script:                           Multi-Volume Archives.
+                                                              (line  80)
+* Interactive operation:                 interactive.         (line   6)
+* ISO 8601 date format:                  Calendar date items. (line  30)
+* items in date strings:                 General date syntax. (line   6)
+* Labeling an archive:                   label.               (line   6)
+* Labeling multi-volume archives:        label.               (line   6)
+* Labels on the archive media:           label.               (line   6)
+* language, in dates:                    General date syntax. (line  40)
+* Large lists of file names on small machines: Same Order.    (line   6)
+* large values:                          Large or Negative Values.
+                                                              (line   6)
+* last DAY:                              Day of week items.   (line  15)
+* last in date strings:                  General date syntax. (line  26)
+* Listing all tar options:               help.                (line  26)
+* listing member and file names:         list.                (line  41)
+* Listing volume label:                  label.               (line  29)
+* Lists of file names:                   files.               (line   6)
+* Local and remote archives:             file.                (line  73)
+* long-opt-col:                          Configuring Help Summary.
+                                                              (line  87)
+* MacKenzie, David:                      Authors of get_date. (line   6)
+* member:                                Definitions.         (line  15)
+* member name:                           Definitions.         (line  15)
+* Members, replacing with other members: append.              (line  49)
+* Meyering, Jim:                         Authors of get_date. (line   6)
+* Middle of the archive, starting in the: Starting File.      (line  11)
+* midnight in date strings:              Time of day items.   (line  22)
+* minute in date strings:                Relative items in date strings.
+                                                              (line  15)
+* minutes, time zone correction by:      Time of day items.   (line  30)
+* Modes of extracted files:              Setting Access Permissions.
+                                                              (line   6)
+* Modification time, excluding files by: after.               (line   8)
+* Modification times of extracted files: Data Modification Times.
+                                                              (line   6)
+* month in date strings:                 Relative items in date strings.
+                                                              (line  15)
+* month names in date strings:           Calendar date items. (line  38)
+* months, written-out:                   General date syntax. (line  36)
+* MT:                                    General-Purpose Variables.
+                                                              (line  69)
+* MT_BEGIN:                              Magnetic Tape Control.
+                                                              (line  11)
+* MT_OFFLINE:                            Magnetic Tape Control.
+                                                              (line  32)
+* MT_REWIND:                             Magnetic Tape Control.
+                                                              (line  21)
+* MT_STATUS:                             Magnetic Tape Control.
+                                                              (line  42)
+* Multi-volume archives:                 Multi-Volume Archives.
+                                                              (line   6)
+* Mutli-volume archives in PAX format, extracting using non-GNU tars: Split Recovery.
+                                                              (line  17)
+* Mutli-volume archives, extracting using non-GNU tars: Split Recovery.
+                                                              (line   6)
+* Naming an archive:                     file.                (line   8)
+* negative time stamps:                  Large or Negative Values.
+                                                              (line   6)
+* next DAY:                              Day of week items.   (line  15)
+* next in date strings:                  General date syntax. (line  26)
+* noon in date strings:                  Time of day items.   (line  22)
+* now in date strings:                   Relative items in date strings.
+                                                              (line  33)
+* ntape device:                          Many.                (line   6)
+* NUL terminated file names:             nul.                 (line   6)
+* Number of blocks per record:           Blocking Factor.     (line   6)
+* Number of bytes per record:            Blocking Factor.     (line   6)
+* numbered backup method:                backup.              (line  55)
+* numbers, written-out:                  General date syntax. (line  26)
+* Obtaining help:                        help.                (line  26)
+* Obtaining total status information:    verbose.             (line  46)
+* Old GNU archive format:                gnu.                 (line   6)
+* Old GNU sparse format:                 Old GNU Format.      (line   6)
+* Old style archives:                    old.                 (line   6)
+* Old style format:                      old.                 (line   6)
+* opt-doc-col:                           Configuring Help Summary.
+                                                              (line 127)
+* option syntax, traditional:            Old Options.         (line  60)
+* Options when reading archives:         Reading.             (line   6)
+* Options, archive format specifying:    Format Variations.   (line   6)
+* Options, format specifying:            Format Variations.   (line   6)
+* ordinal numbers:                       General date syntax. (line  26)
+* Overwriting old files, prevention:     Dealing with Old Files.
+                                                              (line  16)
+* pattern, genfile:                      Generate Mode.       (line  39)
+* PAX archive format:                    posix.               (line   6)
+* Permissions of extracted files:        Setting Access Permissions.
+                                                              (line   6)
+* Pinard, F.:                            Authors of get_date. (line  14)
+* pm in date strings:                    Time of day items.   (line  22)
+* POSIX archive format:                  posix.               (line   6)
+* Progress information:                  verbose.             (line  83)
+* Protecting old files:                  Dealing with Old Files.
+                                                              (line  26)
+* pure numbers in date strings:          Pure numbers in date strings.
+                                                              (line   6)
+* Reading file names from a file:        files.               (line   6)
+* Reading incomplete records:            Reading.             (line   8)
+* Record Size:                           Blocking Factor.     (line   6)
+* Records, incomplete:                   Reading.             (line   8)
+* Recursion in directories, avoiding:    recurse.             (line   8)
+* relative items in date strings:        Relative items in date strings.
+                                                              (line   6)
+* Remote devices:                        file.                (line  62)
+* remote tape drive:                     Remote Tape Server.  (line   6)
+* Removing files from an archive:        delete.              (line   8)
+* Replacing members with other members:  append.              (line  49)
+* reporting bugs:                        Reports.             (line   6)
+* RESTORE_BEGIN:                         User Hooks.          (line  39)
+* RESTORE_END:                           User Hooks.          (line  42)
+* Resurrecting files from an archive:    extract.             (line   8)
+* Retrieving files from an archive:      extract.             (line   8)
+* return status:                         Synopsis.            (line  67)
+* rmargin:                               Configuring Help Summary.
+                                                              (line 160)
+* rmt:                                   Remote Tape Server.  (line   6)
+* RSH:                                   General-Purpose Variables.
+                                                              (line  72)
+* RSH_COMMAND:                           General-Purpose Variables.
+                                                              (line  77)
+* Running out of space:                  Scarce.              (line   8)
+* Salz, Rich:                            Authors of get_date. (line   6)
+* short-opt-col:                         Configuring Help Summary.
+                                                              (line  79)
+* simple backup method:                  backup.              (line  64)
+* SIMPLE_BACKUP_SUFFIX:                  backup.              (line  68)
+* SLEEP_MESSAGE:                         General-Purpose Variables.
+                                                              (line 111)
+* SLEEP_TIME:                            General-Purpose Variables.
+                                                              (line  97)
+* Small memory:                          Scarce.              (line   8)
+* Sparse Files:                          sparse.              (line   6)
+* sparse files v.0.0, extracting with non-GNU tars: Sparse Recovery.
+                                                              (line  92)
+* sparse files v.0.1, extracting with non-GNU tars: Sparse Recovery.
+                                                              (line  92)
+* sparse files v.1.0, extracting with non-GNU tars: Sparse Recovery.
+                                                              (line  17)
+* Sparse files, creating using genfile:  Generate Mode.       (line  55)
+* sparse files, extracting with non-GNU tars: Sparse Recovery.
+                                                              (line   6)
+* sparse formats:                        Sparse Formats.      (line   6)
+* sparse formats, defined:               sparse.              (line  50)
+* sparse formats, Old GNU:               Old GNU Format.      (line   6)
+* sparse formats, v.0.0:                 PAX 0.               (line   6)
+* sparse formats, v.0.1:                 PAX 0.               (line  52)
+* sparse formats, v.1.0:                 PAX 1.               (line   6)
+* sparse versions:                       Sparse Formats.      (line   6)
+* Specifying archive members:            Selecting Archive Members.
+                                                              (line   6)
+* Specifying files to act on:            Selecting Archive Members.
+                                                              (line   6)
+* Standard input and output:             file.                (line  41)
+* Standard output, writing extracted files to: Writing to Standard Output.
+                                                              (line   6)
+* Storing archives in compressed format: gzip.                (line   6)
+* Symbolic link as file name:            dereference.         (line   6)
+* TAPE:                                  file tutorial.       (line  14)
+* tape blocking:                         Blocking Factor.     (line 194)
+* tape marks:                            Many.                (line  44)
+* tape positioning:                      Many.                (line  26)
+* TAPE_FILE:                             General-Purpose Variables.
+                                                              (line  19)
+* Tapes, using --delete and:             delete.              (line  19)
+* TAR:                                   General-Purpose Variables.
+                                                              (line 115)
+* tar:                                   What tar Does.       (line   6)
+* tar archive:                           Definitions.         (line   6)
+* Tar archive formats:                   Formats.             (line   6)
+* tar entry:                             Naming tar Archives. (line  11)
+* tar file:                              Naming tar Archives. (line  11)
+* tar to a remote device:                file.                (line  62)
+* tar to standard input and output:      file.                (line  41)
+* TAR_ARCHIVE, info script environment variable: Multi-Volume Archives.
+                                                              (line 100)
+* TAR_ATIME, to-command environment:     Writing to an External Program.
+                                                              (line  49)
+* TAR_CTIME, to-command environment:     Writing to an External Program.
+                                                              (line  58)
+* TAR_FD, info script environment variable: Multi-Volume Archives.
+                                                              (line 114)
+* TAR_FILENAME, to-command environment:  Writing to an External Program.
+                                                              (line  37)
+* TAR_FILETYPE, to-command environment:  Writing to an External Program.
+                                                              (line  22)
+* TAR_FORMAT, info script environment variable: Multi-Volume Archives.
+                                                              (line 110)
+* TAR_GID, to-command environment:       Writing to an External Program.
+                                                              (line  67)
+* TAR_GNAME, to-command environment:     Writing to an External Program.
+                                                              (line  46)
+* TAR_MODE, to-command environment:      Writing to an External Program.
+                                                              (line  34)
+* TAR_MTIME, to-command environment:     Writing to an External Program.
+                                                              (line  55)
+* TAR_OPTIONS, environment variable:     using tar options.   (line  30)
+* TAR_REALNAME, to-command environment:  Writing to an External Program.
+                                                              (line  40)
+* TAR_SIZE, to-command environment:      Writing to an External Program.
+                                                              (line  61)
+* TAR_SUBCOMMAND, info script environment variable: Multi-Volume Archives.
+                                                              (line 106)
+* TAR_UID, to-command environment:       Writing to an External Program.
+                                                              (line  64)
+* TAR_UNAME, to-command environment:     Writing to an External Program.
+                                                              (line  43)
+* TAR_VERSION, info script environment variable: Multi-Volume Archives.
+                                                              (line  97)
+* TAR_VOLUME, info script environment variable: Multi-Volume Archives.
+                                                              (line 103)
+* tarcat:                                Tarcat.              (line   6)
+* this in date strings:                  Relative items in date strings.
+                                                              (line  33)
+* time of day item:                      Time of day items.   (line   6)
+* time zone correction:                  Time of day items.   (line  30)
+* time zone item <1>:                    Time zone items.     (line   6)
+* time zone item:                        General date syntax. (line  44)
+* today in date strings:                 Relative items in date strings.
+                                                              (line  33)
+* tomorrow in date strings:              Relative items in date strings.
+                                                              (line  29)
+* TZ:                                    Specifying time zone rules.
+                                                              (line   6)
+* Ultrix 3.1 and write failure:          Remote Tape Server.  (line  40)
+* unpacking:                             Definitions.         (line  22)
+* Updating an archive:                   update.              (line   8)
+* usage-indent:                          Configuring Help Summary.
+                                                              (line 156)
+* Using encrypted archives:              gzip.                (line 113)
+* ustar archive format:                  ustar.               (line   6)
+* uuencode:                              Applications.        (line   8)
+* v7 archive format:                     old.                 (line   6)
+* Verbose operation:                     verbose.             (line  18)
+* Verifying a write operation:           verify.              (line   6)
+* Verifying the currency of an archive:  compare.             (line   6)
+* Version of the tar program:            help.                (line   6)
+* version-control Emacs variable:        backup.              (line  49)
+* VERSION_CONTROL:                       backup.              (line  41)
+* volno file:                            Multi-Volume Archives.
+                                                              (line  71)
+* VOLNO_FILE:                            General-Purpose Variables.
+                                                              (line  82)
+* Volume label, listing:                 label.               (line  29)
+* Volume number file:                    Multi-Volume Archives.
+                                                              (line  71)
+* week in date strings:                  Relative items in date strings.
+                                                              (line  15)
+* Where is the archive?:                 file.                (line   8)
+* Working directory, specifying:         directory.           (line   6)
+* Writing extracted files to standard output: Writing to Standard Output.
+                                                              (line   6)
+* Writing new archives:                  file.                (line  36)
+* XLIST:                                 General-Purpose Variables.
+                                                              (line  87)
+* xsparse:                               Sparse Recovery.     (line  13)
+* year in date strings:                  Relative items in date strings.
+                                                              (line  15)
+* yesterday in date strings:             Relative items in date strings.
+                                                              (line  29)
+
+