+@node extract options, backup, Advanced tar, operations
+@section Options Used by @code{--extract}
+@UNREVISED
+
+@FIXME{i need to get dan to go over these options with me and see if
+there's a better way of organizing them.}
+
+The previous chapter showed how to use @value{op-extract} to extract
+an archive into the filesystem. Various options cause @code{tar} to
+extract more information than just file contents, such as the owner,
+the permissions, the modification date, and so forth. This section
+presents options to be used with @samp{--extract} when certain special
+considerations arise. You may review the information presented in
+@ref{extract} for more basic information about the
+@samp{--extract} operation.
+
+@menu
+* Reading:: Options to Help Read Archives
+* Writing:: Changing How @code{tar} Writes Files
+* Scarce:: Coping with Scarce Resources
+@end menu
+
+@node Reading, Writing, extract options, extract options
+@subsection Options to Help Read Archives
+@cindex Options when reading archives
+@cindex Reading incomplete records
+@cindex Records, incomplete
+@cindex End-of-archive entries, ignoring
+@cindex Ignoring end-of-archive entries
+@cindex Large lists of file names on small machines
+@cindex Small memory
+@cindex Running out of space
+@UNREVISED
+
+Normally, @code{tar} will request data in full record increments from
+an archive storage device. If the device cannot return a full record,
+@code{tar} will report an error. However, some devices do not always
+return full records, or do not require the last record of an archive to
+be padded out to the next record boundary. To keep reading until you
+obtain a full record, or to accept an incomplete record if it contains
+an end-of-archive marker, specify the @value{op-read-full-records} option
+in conjunction with the @value{op-extract} or @value{op-list} operations.
+@value{xref-read-full-records}.
+
+The @value{op-read-full-records} option is turned on by default when
+@code{tar} reads an archive from standard input, or from a remote
+machine. This is because on BSD Unix systems, attempting to read a
+pipe returns however much happens to be in the pipe, even if it is
+less than was requested. If this option were not enabled, @code{tar}
+would fail as soon as it read an incomplete record from the pipe.
+
+If you're not sure of the blocking factor of an archive, you can
+read the archive by specifying @value{op-read-full-records} and
+@value{op-blocking-factor}, using a blocking factor larger than what the
+archive uses. This lets you avoid having to determine the blocking factor
+of an archive. @value{xref-blocking-factor}.
+
+@menu
+* read full records::
+* Ignore Zeros::
+* Ignore Failed Read::
+@end menu
+
+@node read full records, Ignore Zeros, Reading, Reading
+@unnumberedsubsubsec Reading Full Records
+
+@FIXME{need sentence or so of intro here}
+
+@table @kbd
+@item --read-full-records
+@item -B
+Use in conjunction with @value{op-extract} to read an archive which
+contains incomplete records, or one which has a blocking factor less
+than the one specified.
+@end table
+
+@node Ignore Zeros, Ignore Failed Read, read full records, Reading
+@unnumberedsubsubsec Ignoring Blocks of Zeros
+
+Normally, @code{tar} stops reading when it encounters a block of zeros
+between file entries (which usually indicates the end of the archive).
+@value{op-ignore-zeros} allows @code{tar} to completely read an archive
+which contains a block of zeros before the end (i.e.@: a damaged
+archive, or one which was created by @code{cat}-ing several archives
+together).
+
+The @value{op-ignore-zeros} option is turned off by default because many
+versions of @code{tar} write garbage after the end-of-archive entry,
+since that part of the media is never supposed to be read. GNU
+@code{tar} does not write after the end of an archive, but seeks to
+maintain compatablity among archiving utilities.
+
+@table @kbd
+@item --ignore-zeros
+@itemx -i
+To ignore blocks of zeros (ie.@: end-of-archive entries) which may be
+encountered while reading an archive. Use in conjunction with
+@value{op-extract} or @value{op-list}.
+@end table
+
+@node Ignore Failed Read, , Ignore Zeros, Reading
+@unnumberedsubsubsec Ignore Fail Read
+
+@FIXME{Is this in the right place? It doesn't exist anywhere else in
+the book (except the appendix), and has no further explanation. For that
+matter, what does it mean?!}
+
+@table @kbd
+@item --ignore-failed-read
+Do not exit with nonzero on unreadable files or directories.
+@end table
+
+@node Writing, Scarce, Reading, extract options
+@subsection Changing How @code{tar} Writes Files
+@cindex Overwriting old files, prevention
+@cindex Protecting old files
+@cindex Modification times of extracted files
+@cindex Permissions of extracted files
+@cindex Modes of extracted files
+@cindex Writing extracted files to standard output
+@cindex Standard output, writing extracted files to
+@UNREVISED
+
+@FIXME{need to mention the brand new option, --backup}
+
+@menu
+* Prevention Overwriting::
+* Keep Old Files::
+* Unlink First::
+* Recursive Unlink::
+* Modification Times::
+* Setting Access Permissions::
+* Writing to Standard Output::
+* remove files::
+@end menu
+
+@node Prevention Overwriting, Keep Old Files, Writing, Writing
+@unnumberedsubsubsec Options to Prevent Overwriting Files
+
+Normally, @code{tar} writes extracted files into the file system without
+regard to the files already on the system; i.e., files with the same
+names as archive members are overwritten when the archive is extracted.
+If the name of a corresponding file name is a symbolic link, the file
+pointed to by the symbolic link will be overwritten instead of the
+symbolic link itself (if this is possible). Moreover, special devices,
+empty directories and even symbolic links are automatically removed if
+they are found to be on the way of the proper extraction.
+
+To prevent @code{tar} from extracting an archive member from an archive
+if doing so will overwrite a file in the file system, use
+@value{op-keep-old-files} in conjunction with @samp{--extract}. When
+this option is specified, @code{tar} will report an error stating the
+name of the files in conflict instead of overwriting the file with the
+corresponding extracted archive member.
+
+@FIXME{these two P's have problems. i don't understand what they're
+trying to talk about well enough to fix them; i may have just made them
+worse (in particular the first of the two). waiting to talk with hag.}
+
+The @value{op-unlink-first} option removes existing files, symbolic links,
+empty directories, devices, etc., @emph{prior} to extracting over them.
+In particular, using this option will prevent replacing an already existing
+symbolic link by the name of an extracted file, since the link itself
+is removed prior to the extraction, rather than the file it points to.
+On some systems, the backing store for the executable @emph{is} the
+original program text. You could use the @value{op-unlink-first} option
+to prevent segmentation violations or other woes when extracting arbitrary
+executables over currently running copies. Note that if something goes
+wrong with the extraction and you @emph{did} use this option, you might
+end up with no file at all. Without this option, if something goes wrong
+with the extraction, the existing file is not overwritten and preserved.
+
+@FIXME{huh?} If you specify the @value{op-recursive-unlink} option,
+@code{tar} removes @emph{anything} that keeps you from extracting a file
+as far as current permissions will allow it. This could include removal
+of the contents of a full directory hierarchy. For example, someone
+using this feature may be very surprised at the results when extracting
+a directory entry from the archive. This option can be dangerous; be
+very aware of what you are doing if you choose to use it.
+
+@menu
+* Keep Old Files::
+* Unlink First::
+* Recursive Unlink::
+@end menu
+
+@node Keep Old Files, Unlink First, Prevention Overwriting, Writing
+@unnumberedsubsubsec Keep Old Files
+
+@table @kbd
+@item --keep-old-files
+@itemx -k
+Do not overwrite existing files from archive. The
+@value{op-keep-old-files} option prevents @code{tar} from over-writing
+existing files with files with the same name from the archive.
+The @value{op-keep-old-files} option is meaningless with @value{op-list}.
+Prevents @code{tar} from overwriting files in the file system during
+extraction.
+@end table
+
+@node Unlink First, Recursive Unlink, Keep Old Files, Writing
+@unnumberedsubsubsec Unlink First
+
+@table @kbd
+@item --unlink-first
+@itemx -U
+Try removing files before extracting over them, instead of trying to
+overwrite them.
+@end table
+
+@node Recursive Unlink, Modification Times, Unlink First, Writing
+@unnumberedsubsubsec Recursive Unlink
+
+@table @kbd
+@item --recursive-unlink
+When this option is specified, try removing files and directory hierarchies
+before extracting over them. @emph{This is a dangerous option!}
+@end table
+
+Some people argue that GNU @code{tar} should not hesitate to overwrite
+files with other files when extracting. When extracting a @code{tar}
+archive, they expect to see a faithful copy of the state of the filesystem
+when the archive was created. It is debatable that this would always
+be a proper behaviour. For example, suppose one has an archive in
+which @file{usr/local} is a link to @file{usr/local2}. Since then,
+maybe the site removed the link and renamed the whole hierarchy from
+@file{/usr/local2} to @file{/usr/local}. Such things happen all the time.
+I guess it would not be welcome at all that GNU @code{tar} removes the
+whole hierarchy just to make room for the link to be reinstated (unless it
+@emph{also} simultaneously restores the full @file{/usr/local2}, of course!
+GNU @code{tar} is indeed able to remove a whole hierarchy to reestablish a
+symbolic link, for example, but @emph{only if} @value{op-recursive-unlink}
+is specified to allow this behaviour. In any case, single files are
+silently removed.
+
+@node Modification Times, Setting Access Permissions, Recursive Unlink, Writing
+@unnumberedsubsubsec Setting Modification Times
+
+Normally, @code{tar} sets the modification times of extracted files to
+the modification times recorded for the files in the archive, but
+limits the permissions of extracted files by the current @code{umask}
+setting.
+
+To set the modification times of extracted files to the time when
+the files were extracted, use the @value{op-touch} option in
+conjunction with @value{op-extract}.
+
+@table @kbd
+@item --touch
+@itemx -m
+Sets the modification time of extracted archive members to the time
+they were extracted, not the time recorded for them in the archive.
+Use in conjunction with @value{op-extract}.
+@end table
+
+@node Setting Access Permissions, Writing to Standard Output, Modification Times, Writing
+@unnumberedsubsubsec Setting Access Permissions
+
+To set the modes (access permissions) of extracted files to those
+recorded for those files in the archive, use @samp{--same-persmissions}
+in conjunction with the @value{op-extract} operation. @FIXME{Should be
+aliased to ignore-umask.}
+
+@table @kbd
+@item --preserve-permission
+@itemx --same-permission
+@itemx --ignore-umask
+@itemx -p
+Set modes of extracted archive members to those recorded in the
+archive, instead of current umask settings. Use in conjunction with
+@value{op-extract}.
+@end table
+
+@FIXME{Following paragraph needs to be rewritten: why doesnt' this cat
+files together, why is this useful. is it really useful with
+more than one file?}
+
+@node Writing to Standard Output, remove files, Setting Access Permissions, Writing
+@unnumberedsubsubsec Writing to Standard Output
+
+To write the extracted files to the standard output, instead of
+creating the files on the file system, use @value{op-to-stdout} in
+conjunction with @value{op-extract}. This option is useful if you are
+extracting files to send them through a pipe, and do not need to
+preserve them in the file system. If you extract multiple members,
+they appear on standard output concatenated, in the order they are
+found in the archive.
+
+@table @kbd
+@item --to-stdout
+@itemx -O
+Writes files to the standard output. Used in conjunction with
+@value{op-extract}. Extract files to standard output. When this option
+is used, instead of creating the files specified, @code{tar} writes
+the contents of the files extracted to its standard output. This may
+be useful if you are only extracting the files in order to send them
+through a pipe. This option is meaningless with @value{op-list}.
+@end table
+
+@FIXME{Why would you want to do such a thing, how are files separated on
+the standard output? is this useful with more that one file? Are
+pipes the real reason?}
+
+@node remove files, , Writing to Standard Output, Writing
+@unnumberedsubsubsec Removing Files
+
+@FIXME{the various macros in the front of the manual think that this
+option goes in this section. i have no idea; i only know it's nowhere
+else in the book...}
+
+@table @kbd
+@item --remove-files
+Remove files after adding them to the archive.
+@end table
+
+@node Scarce, , Writing, extract options
+@subsection Coping with Scarce Resources
+@cindex Middle of the archive, starting in the
+@cindex Running out of space during extraction
+@cindex Disk space, running out of
+@cindex Space on the disk, recovering from lack of
+@UNREVISED
+
+@menu
+* Starting File::
+* Same Order::
+@end menu
+
+@node Starting File, Same Order, Scarce, Scarce
+@unnumberedsubsubsec Starting File
+
+@table @kbd
+@item --starting-file=@var{name}
+@itemx -K @var{name}
+Starts an operation in the middle of an archive. Use in conjunction
+with @value{op-extract} or @value{op-list}.
+@end table
+
+If a previous attempt to extract files failed due to lack of disk
+space, you can use @value{op-starting-file} to start extracting only
+after member @var{name} of the archive. This assumes, of course, that
+there is now free space, or that you are now extracting into a
+different file system. (You could also choose to suspend @code{tar},
+remove unnecessary files from the file system, and then restart the
+same @code{tar} operation. In this case, @value{op-starting-file} is
+not necessary. @value{xref-incremental}, @value{xref-interactive},
+and @value{ref-exclude}.)
+
+@node Same Order, , Starting File, Scarce
+@unnumberedsubsubsec Same Order
+
+@table @kbd
+@item --same-order
+@itemx --preserve-order
+@itemx -s
+To process large lists of file names on machines with small amounts of
+memory. Use in conjunction with @value{op-compare},
+@value{op-list}
+or @value{op-extract}.
+@end table
+
+@FIXME{we don't need/want --preserve to exist any more (from melissa:
+ie, don't want that *version* of the option to exist, or don't want
+the option to exist in either version?}
+
+@FIXME{i think this explanation is lacking.}
+
+The @value{op-same-order} option tells @code{tar} that the list of file
+names to be listed or extracted is sorted in the same order as the
+files in the archive. This allows a large list of names to be used,
+even on a small machine that would not otherwise be able to hold all
+the names in memory at the same time. Such a sorted list can easily be
+created by running @samp{tar -t} on the archive and editing its output.
+
+This option is probably never needed on modern computer systems.
+
+@node backup, Applications, extract options, operations
+@section Backup options
+
+@cindex backup options
+
+GNU @code{tar} offers options for making backups of files before writing
+new versions. These options control the details of these backups.
+They may apply to the archive itself before it is created or rewritten,
+as well as individual extracted members. Other GNU programs (@code{cp},
+@code{install}, @code{ln}, and @code{mv}, for example) offer similar
+options.
+
+Backup options may prove unexpectedly useful when extracting archives
+containing many members having identical name, or when extracting archives
+on systems having file name limitations, making different members appear
+has having similar names through the side-effect of name truncation.
+(This is true only if we have a good scheme for truncated backup names,
+which I'm not sure at all: I suspect work is needed in this area.)
+When any existing file is backed up before being overwritten by extraction,
+then clashing files are automatically be renamed to be unique, and the
+true name is kept for only the last file of a series of clashing files.
+By using verbose mode, users may track exactly what happens.
+
+At the detail level, some decisions are still experimental, and may
+change in the future, we are waiting comments from our users. So, please
+do not learn to depend blindly on the details of the backup features.
+For example, currently, directories themselves are never renamed through
+using these options, so, extracting a file over a directory still has
+good chances to fail. Also, backup options apply to created archives,
+not only to extracted members. For created archives, backups will not
+be attempted when the archive is a block or character device, or when it
+refers to a remote file.
+
+For the sake of simplicity and efficiency, backups are made by renaming old
+files prior to creation or extraction, and not by copying. The original
+name is restored if the file creation fails. If a failure occurs after a
+partial extraction of a file, both the backup and the partially extracted
+file are kept.
+
+@table @samp
+
+@item --backup
+@opindex --backup
+@cindex backups, making
+Make backups of files that are about to be overwritten or removed.
+Without this option, the original versions are destroyed.
+
+@item --suffix=@var{suffix}
+@opindex --suffix
+@cindex backup suffix
+@vindex SIMPLE_BACKUP_SUFFIX
+Append @var{suffix} to each backup file made with @samp{-b}. If this
+option is not specified, the value of the @code{SIMPLE_BACKUP_SUFFIX}
+environment variable is used. And if @code{SIMPLE_BACKUP_SUFFIX} is not
+set, the default is @samp{~}, just as in Emacs.
+
+@item --version-control=@var{method}
+@opindex --version-control
+@vindex VERSION_CONTROL
+@cindex backup files, type made
+Use @var{method} to determine the type of backups made with @value{op-backup}.
+If this option is not specified, the value of the @code{VERSION_CONTROL}
+environment variable is used. And if @code{VERSION_CONTROL} is not set,
+the default backup type is @samp{existing}.
+
+@vindex version-control @r{Emacs variable}
+This option corresponds to the Emacs variable @samp{version-control};
+the same values for @var{method} are accepted as in Emacs. This options
+also more descriptive name. The valid @var{method}s (unique
+abbreviations are accepted):
+
+@table @samp
+@item t
+@itemx numbered
+@opindex numbered @r{backup method}
+Always make numbered backups.
+
+@item nil
+@itemx existing
+@opindex existing @r{backup method}
+Make numbered backups of files that already have them, simple backups
+of the others.
+
+@item never
+@itemx simple
+@opindex simple @r{backup method}
+Always make simple backups.
+
+@end table
+
+@end table
+
+Some people express the desire to @emph{always} use the @var{op-backup}
+option, by defining some kind of alias or script. This is not as easy
+as one may thing, due to the fact old style options should appear first
+and consume arguments a bit inpredictably for an alias or script. But,
+if you are ready to give up using old style options, you may resort to
+using something like (a Bourne shell function here):
+
+@example
+tar () @{ /usr/local/bin/tar --backup $*; @}
+@end example
+
+@node Applications, looking ahead, backup, operations
+@section Notable @code{tar} Usages
+@UNREVISED
+
+@FIXME{Using Unix file linking capability to recreate directory
+structures---linking files into one subdirectory and then
+@code{tar}ring that directory.}
+
+@FIXME{Nice hairy example using absolute-names, newer, etc.}
+
+@findex uuencode
+You can easily use archive files to transport a group of files from
+one system to another: put all relevant files into an archive on one
+computer system, transfer the archive to another system, and extract
+the contents there. The basic transfer medium might be magnetic tape,
+Internet FTP, or even electronic mail (though you must encode the
+archive with @code{uuencode} in order to transport it properly by
+mail). Both machines do not have to use the same operating system, as
+long as they both support the @code{tar} program.
+
+For example, here is how you might copy a directory's contents from
+one disk to another, while preserving the dates, modes, owners and
+link-structure of all the files therein. In this case, the transfer
+medium is a @dfn{pipe}, which is one a Unix redirection mechanism:
+
+@smallexample
+$ @kbd{cd sourcedir; tar -cf - . | (cd targetdir; tar -xf -)}
+@end smallexample
+
+@noindent
+The command also works using short option forms:
+
+@FIXME{The following using standard input/output correct??}
+@smallexample
+$ @w{@kbd{cd sourcedir; tar --create --file=- . | (cd targetdir; tar --extract --file=-)}}
+@end smallexample
+
+@noindent
+This is one of the easiest methods to transfer a @code{tar} archive.
+
+@node looking ahead, , Applications, operations
+@section Looking Ahead: The Rest of this Manual
+
+You have now seen how to use all eight of the operations available to
+@code{tar}, and a number of the possible options. The next chapter
+explains how to choose and change file and archive names, how to use
+files to store names of other files which you can then call as
+arguments to @code{tar} (this can help you save time if you expect to
+archive the same list of files a number of times), and how to
+@FIXME{in case it's not obvious, i'm making this up in some sense
+based on my imited memory of what the next chapter *really* does. i
+just wanted to flesh out this final section a little bit so i'd
+remember to sitck it in here. :-)}
+
+If there are too many files to conveniently list on the command line,
+you can list the names in a file, and @code{tar} will read that file.
+@value{xref-files-from}.
+
+There are various ways of causing @code{tar} to skip over some files,
+and not archive them. @xref{Choosing}.
+
+@node Backups, Choosing, operations, Top
+@chapter Performing Backups and Restoring Files
+@UNREVISED
+
+GNU @code{tar} is distributed along with the scripts which the Free
+Software Foundation uses for performing backups. There is no corresponding
+scripts available yet for doing restoration of files. Even if there is
+a good chance those scripts may be satisfying to you, they are not the
+only scripts or methods available for doing backups and restore. You may
+well create your own, or use more sophisticated packages dedicated to
+that purpose.
+
+Some users are enthusiastic about @code{Amanda} (The Advanced Maryland
+Automatic Network Disk Archiver), a backup system developed by James
+da Silva @file{jds@@cs.umd.edu} and available on many Unix systems.
+This is free software, and it is available at these places:
+
+@example
+http://www.cs.umd.edu/projects/amanda/amanda.html
+ftp://ftp.cs.umd.edu/pub/amanda
+@end example
+
+@ifclear PUBLISH
+
+Here is a possible plan for a future documentation about the backuping
+scripts which are provided within the GNU @code{tar} distribution.
+
+@example
+.* dumps
+. + what are dumps
+
+. + different levels of dumps
+. - full dump = dump everything
+. - level 1, level 2 dumps etc, -
+ A level n dump dumps everything changed since the last level
+ n-1 dump (?)
+
+. + how to use scripts for dumps (ie, the concept)
+. - scripts to run after editing backup specs (details)
+
+. + Backup Specs, what is it.
+. - how to customize
+. - actual text of script [/sp/dump/backup-specs]
+
+. + Problems
+. - rsh doesn't work
+. - rtape isn't installed
+. - (others?)
+
+. + the --incremental option of tar
+
+. + tapes
+. - write protection
+. - types of media
+. : different sizes and types, useful for different things
+. - files and tape marks
+ one tape mark between files, two at end.
+. - positioning the tape
+ MT writes two at end of write,
+ backspaces over one when writing again.
+@end example
+
+@end ifclear
+
+This chapter documents both the provided FSF scripts and @code{tar}
+options which are more specific to usage as a backup tool.
+
+To @dfn{back up} a file system means to create archives that contain
+all the files in that file system. Those archives can then be used to
+restore any or all of those files (for instance if a disk crashes or a
+file is accidently deleted). File system @dfn{backups} are also
+called @dfn{dumps}.
+
+@menu
+* Full Dumps:: Using @code{tar} to Perform Full Dumps
+* Inc Dumps:: Using @code{tar} to Perform Incremental Dumps
+* incremental and listed-incremental:: The Incremental Options
+* Backup Levels:: Levels of Backups
+* Backup Parameters:: Setting Parameters for Backups and Restoration
+* Scripted Backups:: Using the Backup Scripts
+* Scripted Restoration:: Using the Restore Script
+@end menu
+
+@node Full Dumps, Inc Dumps, Backups, Backups
+@section Using @code{tar} to Perform Full Dumps
+@UNREVISED
+
+@cindex full dumps
+@cindex dumps, full
+
+@cindex corrupted archives
+Full dumps should only be made when no other people or programs
+are modifying files in the filesystem. If files are modified while
+@code{tar} is making the backup, they may not be stored properly in
+the archive, in which case you won't be able to restore them if you
+have to. (Files not being modified are written with no trouble, and do
+not corrupt the entire archive.)
+
+You will want to use the @value{op-label} option to give the archive a
+volume label, so you can tell what this archive is even if the label
+falls off the tape, or anything like that.
+
+Unless the filesystem you are dumping is guaranteed to fit on
+one volume, you will need to use the @value{op-multi-volume} option.
+Make sure you have enough tapes on hand to complete the backup.
+
+If you want to dump each filesystem separately you will need to use
+the @value{op-one-file-system} option to prevent @code{tar} from crossing
+filesystem boundaries when storing (sub)directories.
+
+The @value{op-incremental} option is not needed, since this is a complete
+copy of everything in the filesystem, and a full restore from this
+backup would only be done onto a completely empty disk.
+
+Unless you are in a hurry, and trust the @code{tar} program (and your
+tapes), it is a good idea to use the @value{op-verify} option, to make
+sure your files really made it onto the dump properly. This will
+also detect cases where the file was modified while (or just after)
+it was being archived. Not all media (notably cartridge tapes) are
+capable of being verified, unfortunately.
+
+@value{op-listed-incremental} take a file name argument always. If the
+file doesn't exist, run a level zero dump, creating the file. If the
+file exists, uses that file to see what has changed.
+
+@value{op-incremental} @FIXME{look it up}
+
+@value{op-incremental} handle old GNU-format incremental backup.
+
+This option should only be used when creating an incremental backup of
+a filesystem. When the @value{op-incremental} option is used, @code{tar}
+writes, at the beginning of the archive, an entry for each of the
+directories that will be operated on. The entry for a directory
+includes a list of all the files in the directory at the time the
+dump was done, and a flag for each file indicating whether the file
+is going to be put in the archive. This information is used when
+doing a complete incremental restore.
+
+Note that this option causes @code{tar} to create a non-standard
+archive that may not be readable by non-GNU versions of the @code{tar}
+program.
+
+The @value{op-incremental} option means the archive is an incremental
+backup. Its meaning depends on the command that it modifies.
+
+If the @value{op-incremental} option is used with @value{op-list}, @code{tar}
+will list, for each directory in the archive, the list of files in
+that directory at the time the archive was created. This information
+is put out in a format that is not easy for humans to read, but which
+is unambiguous for a program: each file name is preceded by either a
+@samp{Y} if the file is present in the archive, an @samp{N} if the
+file is not included in the archive, or a @samp{D} if the file is
+a directory (and is included in the archive). Each file name is
+terminated by a null character. The last file is followed by an
+additional null and a newline to indicate the end of the data.
+
+If the @value{op-incremental} option is used with @value{op-extract}, then
+when the entry for a directory is found, all files that currently
+exist in that directory but are not listed in the archive @emph{are
+deleted from the directory}.
+
+This behavior is convenient when you are restoring a damaged file
+system from a succession of incremental backups: it restores the
+entire state of the file system to that which obtained when the backup
+was made. If you don't use @value{op-incremental}, the file system will
+probably fill up with files that shouldn't exist any more.
+
+@value{op-listed-incremental} handle new GNU-format incremental backup.
+This option handles new GNU-format incremental backup. It has much the
+same effect as @value{op-incremental}, but also the time when the dump
+is done and the list of directories dumped is written to the given
+@var{file}. When restoring, only files newer than the saved time are
+restored, and the direcotyr list is used to speed up operations.
+
+@value{op-listed-incremental} acts like @value{op-incremental}, but when
+used in conjunction with @value{op-create} will also cause @code{tar} to
+use the file @var{file}, which contains information about the state
+of the filesystem at the time of the last backup, to decide which
+files to include in the archive being created. That file will then
+be updated by @code{tar}. If the file @var{file} does not exist when
+this option is specified, @code{tar} will create it, and include all
+appropriate files in the archive.
+
+The file, which is archive independent, contains the date it was last
+modified and a list of devices, inode numbers and directory names.
+@code{tar} will archive files with newer mod dates or inode change
+times, and directories with an unchanged inode number and device but
+a changed directory name. The file is updated after the files to
+be archived are determined, but before the new archive is actually
+created.
+
+GNU @code{tar} actually writes the file twice: once before the data
+and written, and once after.
+
+@node Inc Dumps, incremental and listed-incremental, Full Dumps, Backups
+@section Using @code{tar} to Perform Incremental Dumps
+@UNREVISED
+
+@cindex incremental dumps
+@cindex dumps, incremental
+
+Performing incremental dumps is similar to performing full dumps,
+although a few more options will usually be needed.
+
+You will need to use the @samp{-N @var{date}} option to tell @code{tar}
+to only store files that have been modified since @var{date}.
+@var{date} should be the date and time of the last full/incremental
+dump.
+
+A standard scheme is to do a @emph{monthly} (full) dump once a month,
+a @emph{weekly} dump once a week of everything since the last monthly
+and a @emph{daily} every day of everything since the last (weekly or
+monthly) dump.
+
+Here is a copy of the script used to dump the filesystems of the
+machines here at the Free Software Foundation. This script is run via
+@code{cron} late at night when people are least likely to be using the
+machines. This script dumps several filesystems from several machines
+at once (via NFS). The operator is responsible for ensuring that all
+the machines will be up at the time the dump happens. If a machine is
+not running, its files will not be dumped, and the next day's
+incremental dump will @emph{not} store files that would have gone onto
+that dump.
+
+@example
+#!/bin/csh
+# Dump thingie
+set now = `date`
+set then = `cat date.nfs.dump`
+/u/hack/bin/tar -c -G -v\
+ -f /dev/rtu20\
+ -b 126\
+ -N "$then"\
+ -V "Dump from $then to $now"\
+ /alpha-bits/gp\
+ /gnu/hack\
+ /hobbes/u\
+ /spiff/u\
+ /sugar-bombs/u
+echo $now > date.nfs.dump
+mt -f /dev/rtu20 rew
+@end example
+
+Output from this script is stored in a file, for the operator to
+read later.
+
+This script uses the file @file{date.nfs.dump} to store the date/time
+of the last dump.
+
+Since this is a streaming tape drive, no attempt to verify the archive
+is done. This is also why the high blocking factor (126) is used.
+The tape drive must also be rewound by the @code{mt} command after
+the dump is made.
+
+@node incremental and listed-incremental, Backup Levels, Inc Dumps, Backups
+@section The Incremental Options
+@UNREVISED
+
+@value{op-incremental} is used in conjunction with @value{op-create},
+@value{op-extract} or @value{op-list} when backing up and restoring file
+systems. An archive cannot be extracted or listed with the
+@value{op-incremental} option specified unless it was created with the
+option specified. This option should only be used by a script, not by
+the user, and is usually disregarded in favor of
+@value{op-listed-incremental}, which is described below.
+
+@value{op-incremental} in conjunction with @value{op-create} causes
+@code{tar} to write, at the beginning of the archive, an entry for
+each of the directories that will be archived. The entry for a
+directory includes a list of all the files in the directory at the
+time the archive was created and a flag for each file indicating
+whether or not the file is going to be put in the archive.
+
+Note that this option causes @code{tar} to create a non-standard
+archive that may not be readable by non-GNU versions of the @code{tar}
+program.
+
+@value{op-incremental} in conjunction with @value{op-extract} causes
+@code{tar} to read the lists of directory contents previously stored
+in the archive, @emph{delete} files in the file system that did not
+exist in their directories when the archive was created, and then
+extract the files in the archive.
+
+This behavior is convenient when restoring a damaged file system from
+a succession of incremental backups: it restores the entire state of
+the file system to that which obtained when the backup was made. If
+@value{op-incremental} isn't specified, the file system will probably
+fill up with files that shouldn't exist any more.
+
+@value{op-incremental} in conjunction with @value{op-list}, causes
+@code{tar} to print, for each directory in the archive, the list of
+files in that directory at the time the archive was created. This
+information is put out in a format that is not easy for humans to
+read, but which is unambiguous for a program: each file name is
+preceded by either a @samp{Y} if the file is present in the archive,
+an @samp{N} if the file is not included in the archive, or a @samp{D}
+if the file is a directory (and is included in the archive). Each
+file name is terminated by a null character. The last file is followed
+by an additional null and a newline to indicate the end of the data.
+
+@value{op-listed-incremental} acts like @value{op-incremental}, but when
+used in conjunction with @value{op-create} will also cause @code{tar}
+to use the file @var{snapshot-file}, which contains information about
+the state of the file system at the time of the last backup, to decide
+which files to include in the archive being created. That file will
+then be updated by @code{tar}. If the file @var{file} does not exist
+when this option is specified, @code{tar} will create it, and include
+all appropriate files in the archive.
+
+The file @var{file}, which is archive independent, contains the date
+it was last modified and a list of devices, inode numbers and
+directory names. @code{tar} will archive files with newer mod dates
+or inode change times, and directories with an unchanged inode number
+and device but a changed directory name. The file is updated after
+the files to be archived are determined, but before the new archive is
+actually created.
+
+Despite it should be obvious that a device has a non-volatile value, NFS
+devices have non-dependable values when an automounter gets in the picture.
+This led to a great deal of spurious redumping in incremental dumps,
+so it is somewhat useless to compare two NFS devices numbers over time.
+So @code{tar} now considers all NFS devices as being equal when it comes
+to comparing directories; this is fairly gross, but there does not seem
+to be a better way to go.
+
+@FIXME{this section needs to be written}
+
+@node Backup Levels, Backup Parameters, incremental and listed-incremental, Backups
+@section Levels of Backups
+@UNREVISED
+
+An archive containing all the files in the file system is called a
+@dfn{full backup} or @dfn{full dump}. You could insure your data by
+creating a full dump every day. This strategy, however, would waste a
+substantial amount of archive media and user time, as unchanged files
+are daily re-archived.
+
+It is more efficient to do a full dump only occasionally. To back up
+files between full dumps, you can a incremental dump. A @dfn{level
+one} dump archives all the files that have changed since the last full
+dump.
+
+A typical dump strategy would be to perform a full dump once a week,
+and a level one dump once a day. This means some versions of files
+will in fact be archived more than once, but this dump strategy makes
+it possible to restore a file system to within one day of accuracy by
+only extracting two archives---the last weekly (full) dump and the
+last daily (level one) dump. The only information lost would be in
+files changed or created since the last daily backup. (Doing dumps
+more than once a day is usually not worth the trouble).
+
+GNU @code{tar} comes with scripts you can use to do full and level-one
+dumps. Using scripts (shell programs) to perform backups and
+restoration is a convenient and reliable alternative to typing out
+file name lists and @code{tar} commands by hand.
+
+Before you use these scripts, you need to edit the file
+@file{backup-specs}, which specifies parameters used by the backup
+scripts and by the restore script. @FIXME{There is no such restore
+script!}. @FIXME-xref{Script Syntax}. Once the backup parameters
+are set, you can perform backups or restoration by running the
+appropriate script.
+
+The name of the restore script is @code{restore}. @FIXME{There is
+no such restore script!}. The names of the level one and full backup
+scripts are, respectively, @code{level-1} and @code{level-0}.
+The @code{level-0} script also exists under the name @code{weekly}, and
+the @code{level-1} under the name @code{daily}---these additional names
+can be changed according to your backup schedule. @FIXME-xref{Scripted
+Restoration}, for more information on running the restoration script.
+@FIXME-xref{Scripted Backups}, for more information on running the
+backup scripts.
+
+@emph{Please Note:} The backup scripts and the restoration scripts are
+designed to be used together. While it is possible to restore files by
+hand from an archive which was created using a backup script, and to create
+an archive by hand which could then be extracted using the restore script,
+it is easier to use the scripts. @FIXME{There is no such restore script!}.
+@value{xref-incremental}, and @value{xref-listed-incremental},
+before making such an attempt.
+
+@FIXME{shorten node names}
+
+@node Backup Parameters, Scripted Backups, Backup Levels, Backups
+@section Setting Parameters for Backups and Restoration
+@UNREVISED
+
+The file @file{backup-specs} specifies backup parameters for the
+backup and restoration scripts provided with @code{tar}. You must
+edit @file{backup-specs} to fit your system configuration and schedule
+before using these scripts.
+
+@FIXME{This about backup scripts needs to be written: BS is a shell
+script .... thus ... @file{backup-specs} is in shell script syntax.}
+
+@FIXME-xref{Script Syntax}, for an explanation of this syntax.
+
+@FIXME{Whats a parameter .... looked at by the backup scripts
+... which will be expecting to find ... now syntax ... value is linked
+to lame ... @file{backup-specs} specifies the following parameters:}
+
+@table @samp
+@item ADMINISTRATOR
+The user name of the backup administrator.
+
+@item BACKUP_HOUR
+The hour at which the backups are done. This can be a number from 0
+to 23, or the string @samp{now}.
+
+@item TAPE_FILE
+The device @code{tar} writes the archive to. This device should be
+attached to the host on which the dump scripts are run.
+
+@FIXME{examples for all ...}
+
+@item TAPE_STATUS
+The command to use to obtain the status of the archive device,
+including error count. On some tape drives there may not be such a
+command; in that case, simply use `TAPE_STATUS=false'.
+
+@item BLOCKING
+The blocking factor @code{tar} will use when writing the dump archive.
+@value{xref-blocking-factor}.
+
+@item BACKUP_DIRS
+A list of file systems to be dumped. You can include any directory
+name in the list---subdirectories on that file system will be
+included, regardless of how they may look to other networked machines.
+Subdirectories on other file systems will be ignored.
+
+The host name specifies which host to run @code{tar} on, and should
+normally be the host that actually contains the file system. However,
+the host machine must have GNU @code{tar} installed, and must be able
+to access the directory containing the backup scripts and their
+support files using the same file name that is used on the machine
+where the scripts are run (ie. what @code{pwd} will print when in that
+directory on that machine). If the host that contains the file system
+does not have this capability, you can specify another host as long as
+it can access the file system through NFS.
+
+@item BACKUP_FILES
+A list of individual files to be dumped. These should be accessible
+from the machine on which the backup script is run.
+
+@FIXME{Same file name, be specific. Through NFS ...}
+
+@end table
+
+@menu
+* backup-specs example:: An Example Text of @file{Backup-specs}
+* Script Syntax:: Syntax for @file{Backup-specs}
+@end menu
+
+@node backup-specs example, Script Syntax, Backup Parameters, Backup Parameters
+@subsection An Example Text of @file{Backup-specs}
+@UNREVISED
+
+The following is the text of @file{backup-specs} as it appears at FSF:
+
+@example
+# site-specific parameters for file system backup.
+
+ADMINISTRATOR=friedman
+BACKUP_HOUR=1
+TAPE_FILE=/dev/nrsmt0
+TAPE_STATUS="mts -t $TAPE_FILE"
+BLOCKING=124
+BACKUP_DIRS="
+ albert:/fs/fsf
+ apple-gunkies:/gd
+ albert:/fs/gd2
+ albert:/fs/gp
+ geech:/usr/jla
+ churchy:/usr/roland
+ albert:/
+ albert:/usr
+ apple-gunkies:/
+ apple-gunkies:/usr
+ gnu:/hack
+ gnu:/u
+ apple-gunkies:/com/mailer/gnu
+ apple-gunkies:/com/archive/gnu"
+
+BACKUP_FILES="/com/mailer/aliases /com/mailer/league*[a-z]"
+
+@end example
+
+@node Script Syntax, , backup-specs example, Backup Parameters
+@subsection Syntax for @file{Backup-specs}
+@UNREVISED
+
+@file{backup-specs} is in shell script syntax. The following
+conventions should be considered when editing the script:
+@FIXME{"conventions?"}
+
+A quoted string is considered to be contiguous, even if it is on more
+than one line. Therefore, you cannot include commented-out lines
+within a multi-line quoted string. BACKUP_FILES and BACKUP_DIRS are
+the two most likely parameters to be multi-line.
+
+A quoted string typically cannot contain wildcards. In
+@file{backup-specs}, however, the parameters BACKUP_DIRS and
+BACKUP_FILES can contain wildcards.
+
+@node Scripted Backups, Scripted Restoration, Backup Parameters, Backups
+@section Using the Backup Scripts
+@UNREVISED
+
+The syntax for running a backup script is:
+
+@example
+@file{script-name} [@var{time-to-be-run}]
+@end example
+
+where @var{time-to-be-run} can be a specific system time, or can be
+@kbd{now}. If you do not specify a time, the script runs at the time
+specified in @file{backup-specs} (@FIXME-pxref{Script Syntax}).
+
+You should start a script with a tape or disk mounted. Once you
+start a script, it prompts you for new tapes or disks as it
+needs them. Media volumes don't have to correspond to archive
+files---a multi-volume archive can be started in the middle of a
+tape that already contains the end of another multi-volume archive.
+The @code{restore} script prompts for media by its archive volume,
+so to avoid an error message you should keep track of which tape
+(or disk) contains which volume of the archive. @FIXME{There is
+no such restore script!}. @FIXME-xref{Scripted Restoration}.
+@FIXME{Have file names changed?}
+
+The backup scripts write two files on the file system. The first is a
+record file in @file{/etc/tar-backup/}, which is used by the scripts
+to store and retrieve information about which files were dumped. This
+file is not meant to be read by humans, and should not be deleted by
+them. @FIXME-xref{incremental and listed-incremental}, for a more
+detailed explanation of this file.
+
+The second file is a log file containing the names of the file systems
+and files dumped, what time the backup was made, and any error
+messages that were generated, as well as how much space was left in
+the media volume after the last volume of the archive was written.
+You should check this log file after every backup. The file name is
+@file{log-@var{mmm-ddd-yyyy}-level-1} or
+@file{log-@var{mmm-ddd-yyyy}-full}.
+
+The script also prints the name of each system being dumped to the
+standard output.
+
+@node Scripted Restoration, , Scripted Backups, Backups
+@section Using the Restore Script
+@UNREVISED
+
+@ifset PUBLISH
+
+The @code{tar} distribution does not provide restoring scripts.
+
+@end ifset
+
+@ifclear PUBLISH
+
+@quotation
+@strong{Warning:} The GNU @code{tar} distribution does @emph{not}
+provide any such @code{restore} script yet. This section is only
+listed here for documentation maintenance purposes. In any case,
+all contents is subject to change as things develop.
+@end quotation
+
+@FIXME{A section on non-scripted restore may be a good idea.}
+
+To restore files that were archived using a scripted backup, use the
+@code{restore} script. The syntax for the script is:
+
+where ***** are the file systems to restore from, and
+***** is a regular expression which specifies which files to
+restore. If you specify --all, the script restores all the files
+in the file system.
+
+You should start the restore script with the media containing the
+first volume of the archive mounted. The script will prompt for other
+volumes as they are needed. If the archive is on tape, you don't need
+to rewind the tape to to its beginning---if the tape head is
+positioned past the beginning of the archive, the script will rewind
+the tape as needed. @FIXME-xref{Media}, for a discussion of tape
+positioning.
+
+If you specify @samp{--all} as the @var{files} argument, the
+@code{restore} script extracts all the files in the archived file
+system into the active file system.
+
+@quotation
+@strong{Warning:} The script will delete files from the active file
+system if they were not in the file system when the archive was made.
+@end quotation
+
+@value{xref-incremental}, and @value{ref-listed-incremental},
+for an explanation of how the script makes that determination.
+
+@FIXME{this may be an option, not a given}
+
+@end ifclear
+
+@node Choosing, Date input formats, Backups, Top
+@chapter Choosing Files and Names for @code{tar}
+@UNREVISED
+
+@FIXME{Melissa (still) Doesn't Really Like This ``Intro'' Paragraph!!!}
+
+Certain options to @code{tar} enable you to specify a name for your
+archive. Other options let you decide which files to include or exclude
+from the archive, based on when or whether files were modified, whether
+the file names do or don't match specified patterns, or whether files
+are in specified directories.
+
+@menu
+* file:: Choosing the Archive's Name
+* Selecting Archive Members::
+* files:: Reading Names from a File
+* exclude:: Excluding Some Files
+* Wildcards::
+* after:: Operating Only on New Files
+* recurse:: Descending into Directories
+* one:: Crossing Filesystem Boundaries
+@end menu
+
+@node file, Selecting Archive Members, Choosing, Choosing
+@section Choosing and Naming Archive Files
+@cindex Naming an archive
+@cindex Archive Name
+@cindex Directing output
+@cindex Choosing an archive file
+@cindex Where is the archive?
+@UNREVISED
+
+@FIXME{should the title of this section actually be, "naming an
+archive"?}
+
+By default, @code{tar} uses an archive file name that was compiled when
+it was built on the system; usually this name refers to some physical
+tape drive on the machine. However, the person who installed @code{tar}
+on the system may not set the default to a meaningful value as far as
+most users are concerned. As a result, you will usually want to tell
+@code{tar} where to find (or create) the archive. The @value{op-file}
+option allows you to either specify or name a file to use as the archive
+instead of the default archive file location.
+
+@table @kbd
+@item --file=@var{archive-name}
+@itemx -f @var{archive-name}
+Name the archive to create or operate on. Use in conjunction with
+any operation.
+@end table
+
+For example, in this @code{tar} command,
+
+@example
+$ @kbd{tar -cvf collection.tar blues folk jazz}
+@end example
+
+@noindent
+@file{collection.tar} is the name of the archive. It must directly
+follow the @samp{-f} option, since whatever directly follows @samp{-f}
+@emph{will} end up naming the archive. If you neglect to specify an
+archive name, you may end up overwriting a file in the working directory
+with the archive you create since @code{tar} will use this file's name
+for the archive name.
+
+An archive can be saved as a file in the file system, sent through a
+pipe or over a network, or written to an I/O device such as a tape,
+floppy disk, or CD write drive.
+
+@cindex Writing new archives
+@cindex Archive creation
+If you do not name the archive, @code{tar} uses the value of the
+environment variable @code{TAPE} as the file name for the archive. If
+that is not available, @code{tar} uses a default, compiled-in archive
+name, usually that for tape unit zero (ie. @file{/dev/tu00}).
+@code{tar} always needs an archive name.
+
+If you use @file{-} as an @var{archive-name}, @code{tar} reads the
+archive from standard input (when listing or extracting files), or
+writes it to standard output (when creating an archive). If you use
+@file{-} as an @var{archive-name} when modifying an archive,
+@code{tar} reads the original archive from its standard input and
+writes the entire new archive to its standard output.
+
+@FIXME{might want a different example here; this is already used in
+"notable tar usages".}
+
+@example
+$ @kbd{cd sourcedir; tar -cf - . | (cd targetdir; tar -xf -)}
+@end example
+
+@FIXME{help!}
+
+@cindex Standard input and output
+@cindex tar to standard input and output
+To specify an archive file on a device attached to a remote machine,
+use the following:
+
+@example
+@kbd{--file=@var{hostname}:/@var{dev}/@var{file name}}
+@end example
+
+@noindent
+@code{tar} will complete the remote connection, if possible, and
+prompt you for a username and password. If you use
+@samp{--file=@@@var{hostname}:/@var{dev}/@var{file name}}, @code{tar}
+will complete the remote connection, if possible, using your username
+as the username on the remote machine.
+
+If the archive file name includes a colon (@samp{:}), then it is assumed
+to be a file on another machine. If the archive file is
+@samp{@var{user}@@@var{host}:@var{file}}, then @var{file} is used on the
+host @var{host}. The remote host is accessed using the @code{rsh}
+program, with a username of @var{user}. If the username is omitted
+(along with the @samp{@@} sign), then your user name will be used.
+(This is the normal @code{rsh} behavior.) It is necessary for the
+remote machine, in addition to permitting your @code{rsh} access, to
+have the @file{/usr/ucb/rmt} program installed. If you need to use a
+file whose name includes a colon, then the remote tape drive behavior
+can be inhibited by using the @value{op-force-local} option.
+
+@FIXME{i know we went over this yesterday, but bob (and now i do again,
+too) thinks it's out of the middle of nowhere. it doesn't seem to tie
+into what came before it well enough <<i moved it now, is it better
+here?>>. bob also comments that if Amanda isn't free software, we
+shouldn't mention it..}
+
+When the archive is being created to @file{/dev/null}, GNU @code{tar}
+tries to minimize input and output operations. The Amanda backup
+system, when used with GNU @code{tar}, has an initial sizing pass which
+uses this feature.
+
+@node Selecting Archive Members, files, file, Choosing
+@section Selecting Archive Members
+@cindex Specifying files to act on
+@cindex Specifying archive members
+
+@dfn{File Name arguments} specify which files in the file system
+@code{tar} operates on, when creating or adding to an archive, or which
+archive members @code{tar} operates on, when reading or deleting from
+an archive. @xref{Operations}.
+
+To specify file names, you can include them as the last arguments on
+the command line, as follows:
+@smallexample
+@kbd{tar} @var{operation} [@var{option1} @var{option2} @dots{}] [@var{file name-1} @var{file name-2} @dots{}]
+@end smallexample
+
+If you specify a directory name as a file name argument, all the files
+in that directory are operated on by @code{tar}.
+
+If you do not specify files when @code{tar} is invoked with
+@value{op-create}, @code{tar} operates on all the non-directory files in
+the working directory. If you specify either @value{op-list} or
+@value{op-extract}, @code{tar} operates on all the archive members in the
+archive. If you specify any operation other than one of these three,
+@code{tar} does nothing.
+
+By default, @code{tar} takes file names from the command line. However,
+there are other ways to specify file or member names, or to modify the
+manner in which @code{tar} selects the files or members upon which to
+operate; @FIXME{add xref here}. In general, these methods work both for
+specifying the names of files and archive members.
+
+@node files, exclude, Selecting Archive Members, Choosing
+@section Reading Names from a File
+@UNREVISED
+
+@cindex Reading file names from a file
+@cindex Lists of file names
+@cindex File Name arguments, alternatives
+Instead of giving the names of files or archive members on the command
+line, you can put the names into a file, and then use the
+@value{op-files-from} option to @code{tar}. Give the name of the file
+which contains the list of files to include as the argument to
+@samp{--files-from}. In the list, the file names should be separated by
+newlines. You will frequently use this option when you have generated
+the list of files to archive with the @code{find} utility.
+
+@table @kbd
+@item --files-from=@var{file name}
+@itemx -T @var{file name}
+Get names to extract or create from file @var{file name}.
+@end table
+
+If you give a single dash as a file name for @samp{--files-from}, (i.e.,
+you specify either @samp{--files-from=-} or @samp{-T -}), then the file
+names are read from standard input.
+
+Unless you are running @code{tar} with @samp{--create}, you can not use
+both @samp{--files-from=-} and @samp{--file=-} (@samp{-f -}) in the same
+command.
+
+@FIXME{add bob's example, from his message on 2-10-97}
+
+The following example shows how to use @code{find} to generate a list of
+files smaller than 400K in length and put that list into a file
+called @file{small-files}. You can then use the @samp{-T} option to
+@code{tar} to specify the files from that file, @file{small-files}, to
+create the archive @file{little.tgz}. (The @samp{-z} option to
+@code{tar} compresses the archive with @code{gzip}; @pxref{gzip} for
+more information.)
+
+@example
+$ @kbd{find . -size -400 -print > small-files}
+$ @kbd{tar -c -v -z -T small-files -f little.tgz}
+@end example
+
+@noindent
+@FIXME{say more here to conclude the example/section?}
+
+@menu
+* nul::
+@end menu
+
+@node nul, , files, files
+@ifinfo
+@unnumberedsubsec @kbd{NUL} Terminated File Names
+@end ifinfo
+
+@cindex File names, terminated by @kbd{NUL}
+@cindex @kbd{NUL} terminated file names
+The @value{op-null} option causes @value{op-files-from} to read file
+names terminated by a @code{NUL} instead of a newline, so files whose
+names contain newlines can be archived using @samp{--files-from}.
+
+@table @kbd
+@item --null
+Only consider @kbd{NUL} terminated file names, instead of files that
+terminate in a newline.
+@end table
+
+The @samp{--null} option is just like the one in GNU @code{xargs} and
+@code{cpio}, and is useful with the @samp{-print0} predicate of GNU
+@code{find}. In @code{tar}, @samp{--null} also causes
+@value{op-directory} options to be treated as file names to archive, in
+case there are any files out there called @file{-C}.
+
+This example shows how to use @code{find} to generate a list of files
+larger than 800K in length and put that list into a file called
+@file{long-files}. The @samp{-print0} option to @code{find} just just
+like @samp{-print}, except that it separates files with a @kbd{NUL}
+rather than with a newline. You can then run @code{tar} with both the
+@samp{--null} and @samp{-T} options to specify that @code{tar} get the
+files from that file, @file{long-files}, to create the archive
+@file{big.tgz}. The @samp{--null} option to @code{tar} will cause
+@code{tar} to recognize the @kbd{NUL} separator between files.
+
+@example
+$ @kbd{find . -size +800 -print0 > long-files}
+$ @kbd{tar -c -v --null --files-from=long-files --file=big.tar}
+@end example
+
+@FIXME{say anything else here to conclude the section?}
+
+@node exclude, Wildcards, files, Choosing
+@section Excluding Some Files
+@cindex File names, excluding files by
+@cindex Excluding files by name and pattern
+@cindex Excluding files by file system
+@UNREVISED
+
+To avoid operating on files whose names match a particular pattern,
+use the @value{op-exclude} or @value{op-exclude-from} options.
+
+@table @kbd
+@item --exclude=@var{pattern}
+Causes @code{tar} to ignore files that match the @var{pattern}.
+@end table
+
+@findex exclude
+The @value{op-exclude} option will prevent any file or member which
+matches the shell wildcards (@var{pattern}) from being operated on
+(@var{pattern} can be a single file name or a more complex expression).
+For example, if you want to create an archive with all the contents of
+@file{/tmp} except the file @file{/tmp/foo}, you can use the command
+@samp{tar --create --file=arch.tar --exclude=foo}. You may give
+multiple @samp{--exclude} options.
+
+@table @kbd
+@item --exclude-from=@var{file}
+@itemx -X @var{file}
+Causes @code{tar} to ignore files that match the patterns listed in
+@var{file}.
+@end table
+
+@findex exclude-from
+Use the @samp{--exclude-from=@var{file-of-patterns}} option to read a
+list of shell wildcards, one per line, from @var{file}; @code{tar} will
+ignore files matching those regular expressions. Thus if @code{tar} is
+called as @w{@samp{tar -c -X foo .}} and the file @file{foo} contains a
+single line @file{*.o}, no files whose names end in @file{.o} will be
+added to the archive.
+
+@FIXME{do the exclude options files need to have stuff separated by
+newlines the same as the files-from option does?}
+
+@menu
+* problems with exclude::
+@end menu
+
+@node problems with exclude, , exclude, exclude
+@unnumberedsubsec Problems with Using the @code{exclude} Options
+
+@FIXME{put in for the editor's/editors' amusement, but should be taken
+out in the final draft, just in case! : }
+
+@ignore
+subtitled: getting screwed using exclewed
+@end ignore
+
+Some users find @samp{exclude} options confusing. Here are some common
+pitfalls:
+
+@itemize @bullet
+@item
+The main operating mode of @code{tar} will always act on file names
+listed on the command line, no matter whether or not there is an
+exclusion which would otherwise affect them. In the example above, if
+you create an archive and exclude files that end with @samp{*.o}, but
+explicitly name the file @samp{catc.o} after all the options have been
+listed, @samp{catc.o} @emph{will} be included in the archive.
+
+@item
+You can sometimes confuse the meanings of @value{op-exclude} and
+@value{op-exclude-from}. Be careful: use @value{op-exclude} when files
+to be excluded are given as a pattern on the command line. Use
+@samp{--exclude-from=@var{file-of-patterns}} to introduce the name of a
+file which contains a list of patterns, one per line; each of these
+patterns can exclude zero, one, or many files.
+
+@item
+When you use @value{op-exclude}, be sure to quote the @var{pattern}
+parameter, so GNU @code{tar} sees wildcard characters like @samp{*}.
+If you do not do this, the shell might expand the @samp{*} itself
+using files at hand, so @code{tar} might receive a list of files
+instead of one pattern, or none at all, making the command somewhat
+illegal. This might not correspond to what you want.
+
+For example, write:
+
+@example
+$ @kbd{tar -c -f @var{archive.tar} -X '*/tmp/*' @var{directory}}
+@end example
+
+@noindent
+rather than:
+
+@example
+$ @kbd{tar -c -f @var{archive.tar} -X */tmp/* @var{directory}}
+@end example
+
+@item
+You must use use shell syntax, or globbing, rather than @code{regexp}
+syntax, when using exclude options in @code{tar}. If you try to use
+@code{regexp} syntax to describe files to be excluded, your command
+might fail.
+
+@item
+In earlier versions of @code{tar}, what is now the
+@samp{--exclude-from=@var{file-of-patterns}} option was called
+@samp{--exclude-@var{pattern}} instead. Now,
+@samp{--exclude=@var{pattern}} applies to patterns listed on the command
+line and @samp{--exclude-from=@var{file-of-patterns}} applies to
+patterns listed in a file.
+
+@end itemize
+
+@node Wildcards, after, exclude, Choosing
+@section Wildcards Patterns and Matching
+
+@dfn{Globbing} is the operation by which @dfn{wildcard} characters,
+@samp{*} or @samp{?} for example, are replaced and expanded into all
+existing files matching the given pattern. However, @code{tar} often
+uses wildcard patterns for matching (or globbing) archive members instead
+of actual files in the filesystem. Wildcard patterns are also used for
+verifying volume labels of @code{tar} archives. This section has the
+purpose of explaining wildcard syntax for @code{tar}.
+
+@FIXME{the next few paragraphs need work.}
+
+A @var{pattern} should be written according to shell syntax, using wildcard
+characters to effect globbing. Most characters in the pattern stand
+for themselves in the matched string, and case is significant: @samp{a}
+will match only @samp{a}, and not @samp{A}. The character @samp{?} in the
+pattern matches any single character in the matched string. The character
+@samp{*} in the pattern matches zero, one, or more single characters in
+the matched string. The character @samp{\} says to take the following
+character of the pattern @emph{literally}; it is useful when one needs to
+match the @samp{?}, @samp{*}, @samp{[} or @samp{\} characters, themselves.
+
+The character @samp{[}, up to the matching @samp{]}, introduces a character
+class. A @dfn{character class} is a list of acceptable characters
+for the next single character of the matched string. For example,
+@samp{[abcde]} would match any of the first five letters of the alphabet.
+Note that within a character class, all of the ``special characters''
+listed above other than @samp{\} lose their special meaning; for example,
+@samp{[-\\[*?]]} would match any of the characters, @samp{-}, @samp{\},
+@samp{[}, @samp{*}, @samp{?}, or @samp{]}. (Due to parsing constraints,
+the characters @samp{-} and @samp{]} must either come @emph{first} or
+@emph{last} in a character class.)
+
+@cindex Excluding characters from a character class
+@cindex Character class, excluding characters from
+If the first character of the class after the opening @samp{[}
+is @samp{!} or @samp{^}, then the meaning of the class is reversed.
+Rather than listing character to match, it lists those characters which
+are @emph{forbidden} as the next single character of the matched string.
+
+Other characters of the class stand for themselves. The special
+construction @samp{[@var{a}-@var{e}]}, using an hyphen between two
+letters, is meant to represent all characters between @var{a} and
+@var{e}, inclusive.
+
+@FIXME{need to add a sentence or so here to make this clear for those
+who don't have dan around.}
+
+Periods (@samp{.}) or forward slashes (@samp{/}) are not considered
+special for wildcard matches. However, if a pattern completely matches
+a directory prefix of a matched string, then it matches the full matched
+string: excluding a directory also excludes all the files beneath it.
+
+There are some discussions floating in the air and asking for modifications
+in the way GNU @code{tar} accomplishes wildcard matches. We perceive
+any change of semantics in this area as a delicate thing to impose on
+GNU @code{tar} users. On the other hand, the GNU project should be
+progressive enough to correct any ill design: compatibility at all price
+is not always a good attitude. In conclusion, it is @emph{possible}
+that slight amendments be later brought to the previous description.
+Your opinions on the matter are welcome.
+
+@node after, recurse, Wildcards, Choosing
+@section Operating Only on New Files
+@cindex Excluding file by age
+@cindex Modification time, excluding files by
+@cindex Age, excluding files by
+@UNREVISED
+
+The @value{op-after-date} option causes @code{tar} to only work on files
+whose modification or inode-changed times are newer than the @var{date}
+given. If you use this option when creating or appending to an archive,
+the archive will only include new files. If you use @samp{--after-date}
+when extracting an archive, @code{tar} will only extract files newer
+than the @var{date} you specify.
+
+If you only want @code{tar} to make the date comparison based on
+modification of the actual contents of the file (rather than inode
+changes), then use the @value{op-newer-mtime} option.
+
+You may use these options with any operation. Note that these options
+differ from the @value{op-update} operation in that they allow you to
+specify a particular date against which @code{tar} can compare when
+deciding whether or not to archive the files.
+
+@table @kbd
+@item --after-date=@var{date}
+@itemx --newer=@var{date}
+@itemx -N @var{date}
+Only store files newer than @var{date}.
+
+Acts on files only if their modification or inode-changed times are
+later than @var{date}. Use in conjunction with any operation.
+
+@item --newer-mtime=@var{date}
+Acts like @value{op-after-date}, but only looks at modification times.
+@end table
+
+These options limit @code{tar} to only operating on files which have
+been modified after the date specified. A file is considered to have
+changed if the contents have been modified, or if the owner,
+permissions, and so forth, have been changed. (For more information on
+how to specify a date, see @ref{Date input formats}; remember that the
+entire date argument must be quoted if it contains any spaces.)
+
+Gurus would say that @value{op-after-date} tests both the @code{mtime}
+(time the contents of the file were last modified) and @code{ctime}
+(time the file's status was last changed: owner, permissions, etc)
+fields, while @value{op-newer-mtime} tests only @code{mtime} field.
+
+To be precise, @value{op-after-date} checks @emph{both} @code{mtime} and
+@code{ctime} and processes the file if either one is more recent than
+@var{date}, while @value{op-newer-mtime} only checks @code{mtime} and
+disregards @code{ctime}. Neither uses @code{atime} (the last time the
+contents of the file were looked at).
+
+Date specifiers can have embedded spaces. Because of this, you may need
+to quote date arguments to keep the shell from parsing them as separate
+arguments.
+
+@FIXME{Need example of --newer-mtime with quoted argument.}
+
+@quotation
+@strong{Please Note:} @value{op-after-date} and @value{op-newer-mtime}
+should not be used for incremental backups. Some files (such as those
+in renamed directories) are not selected properly by these options.
+@xref{incremental and listed-incremental}.
+@end quotation
+
+To select files newer than the modification time of a file that already
+exists, you can use the @samp{--reference} (@samp{-r}) option of GNU
+@code{date}, available in GNU shell utilities 1.13 or later. It returns
+the timestamp of that already existing file; this timestamp expands to
+become the referent date which @samp{--newer} uses to determine which
+files to archive. For example, you could say,
+
+@example
+$ @kbd{tar -cf @var{archive.tar} --newer="`date -r @var{file}`" /home}
+@end example
+
+@noindent
+which tells @FIXME{need to fill this in!}.
+
+@node recurse, one, after, Choosing
+@section Descending into Directories
+@cindex Avoiding recursion in directories
+@cindex Descending directories, avoiding
+@cindex Directories, avoiding recursion
+@cindex Recursion in directories, avoiding
+@UNREVISED
+
+@FIXME{arrggh! this is still somewhat confusing to me. :-< }
+
+@FIXME{show dan bob's comments, from 2-10-97}
+
+Usually, @code{tar} will recursively explore all directories (either
+those given on the command line or through the @value{op-files-from}
+option) for the various files they contain. However, you may not always
+want @code{tar} to act this way.
+
+The @value{op-no-recursion} option inhibits @code{tar}'s recursive descent
+into specified directories. If you specify @samp{--no-recursion}, you can
+use the @code{find} utility for hunting through levels of directories to
+construct a list of file names which you could then pass to @code{tar}.
+@code{find} allows you to be more selective when choosing which files to
+archive; see @ref{files} for more information on using @code{find} with
+@code{tar}, or look.
+
+@table @kbd
+@item --no-recursion
+Prevents @code{tar} from recursively descending directories.
+@end table
+
+When you use @samp{--no-recursion}, GNU @code{tar} grabs directory entries
+themselves, but does not descend on them recursively. Many people use
+@code{find} for locating files they want to back up, and since
+@code{tar} @emph{usually} recursively descends on directories, they have
+to use the @samp{@w{! -d}} option to @code{find} @FIXME{needs more
+explanation or a cite to another info file} as they usually do not want
+all the files in a directory. They then use the @value{op-file-from}
+option to archive the files located via @code{find}.
+
+The problem when restoring files archived in this manner is that the
+directories themselves are not in the archive; so the
+@value{op-same-permissions} option does not affect them---while users
+might really like it to. Specifying @value{op-no-recursion} is a way to
+tell @code{tar} to grab only the directory entries given to it, adding
+no new files on its own.
+
+@FIXME{example here}
+
+@node one, , recurse, Choosing
+@section Crossing Filesystem Boundaries
+@cindex File system boundaries, not crossing
+@UNREVISED
+
+@code{tar} will normally automatically cross file system boundaries in
+order to archive files which are part of a directory tree. You can
+change this behavior by running @code{tar} and specifying
+@value{op-one-file-system}. This option only affects files that are
+archived because they are in a directory that is being archived;
+@code{tar} will still archive files explicitly named on the command line
+or through @value{op-files-from}, regardless of where they reside.
+
+@table @kbd
+@item --one-file-system
+@itemx -l
+Prevents @code{tar} from crossing file system boundaries when
+archiving. Use in conjunction with any write operation.
+@end table
+
+The @samp{--one-file-system} option causes @code{tar} to modify its
+normal behavior in archiving the contents of directories. If a file in
+a directory is not on the same filesystem as the directory itself, then
+@code{tar} will not archive that file. If the file is a directory
+itself, @code{tar} will not archive anything beneath it; in other words,
+@code{tar} will not cross mount points.
+
+It is reported that using this option, the mount point is is archived,
+but nothing under it.
+
+This option is useful for making full or incremental archival backups of
+a file system. If this option is used in conjunction with
+@value{op-verbose}, files that are excluded are mentioned by name on the
+standard error.
+
+@menu
+* directory:: Changing Directory
+* absolute:: Absolute File Names
+@end menu
+
+@node directory, absolute, one, one
+@subsection Changing the Working Directory
+
+@FIXME{need to read over this node now for continuity; i've switched
+things around some.}
+
+@cindex Changing directory mid-stream
+@cindex Directory, changing mid-stream
+@cindex Working directory, specifying
+@UNREVISED
+
+To change the working directory in the middle of a list of file names,
+either on the command line or in a file specified using
+@value{op-files-from}, use @value{op-directory}. This will change the
+working directory to the directory @var{directory} after that point in
+the list.
+
+@table @kbd
+@item --directory=@var{directory}
+@itemx -C @var{directory}
+Changes the working directory in the middle of a command line.
+@end table
+
+For example,
+
+@example
+$ @kbd{tar -c -f jams.tar grape prune -C food cherry}
+@end example
+
+@noindent
+will place the files @file{grape} and @file{prune} from the current
+directory into the archive @file{jams.tar}, followed by the file
+@file{cherry} from the directory @file{food}. This option is especially
+useful when you have several widely separated files that you want to
+store in the same archive.
+
+Note that the file @file{cherry} is recorded in the archive under the
+precise name @file{cherry}, @emph{not} @file{food/cherry}. Thus, the
+archive will contain three files that all appear to have come from the
+same directory; if the archive is extracted with plain @samp{tar
+--extract}, all three files will be written in the current directory.
+
+Contrast this with the command,
+
+@example
+$ @kbd{tar -c -f jams.tar grape prune -C food red/cherry}
+@end example
+
+@noindent
+which records the third file in the archive under the name
+@file{red/cherry} so that, if the archive is extracted using
+@samp{tar --extract}, the third file will be written in a subdirectory
+named @file{orange-colored}.
+
+You can use the @samp{--directory} option to make the archive
+independent of the original name of the directory holding the files.
+The following command places the files @file{/etc/passwd},
+@file{/etc/hosts}, and @file{/lib/libc.a} into the archive
+@file{foo.tar}:
+
+@example
+$ @kbd{tar -c -f foo.tar -C /etc passwd hosts -C /lib libc.a}
+@end example
+
+@noindent
+However, the names of the archive members will be exactly what they were
+on the command line: @file{passwd}, @file{hosts}, and @file{libc.a}.
+They will not appear to be related by file name to the original
+directories where those files were located.
+
+Note that @samp{--directory} options are interpreted consecutively. If
+@samp{--directory} specifies a relative file name, it is interpreted
+relative to the then current directory, which might not be the same as
+the original current working directory of @code{tar}, due to a previous
+@samp{--directory} option.
+
+@FIXME{dan: does this mean that you *can* use the short option form, but
+you can *not* use the long option form with --files-from? or is this
+totally screwed?}
+
+When using @samp{--files-from} (@pxref{files}), you can put @samp{-C}
+options in the file list. Unfortunately, you cannot put
+@samp{--directory} options in the file list. (This interpretation can
+be disabled by using the @value{op-null} option.)
+
+@node absolute, , directory, one
+@subsection Absolute File Names
+@UNREVISED
+
+@table @kbd
+@item -P
+@itemx --absolute-names
+Do not strip leading slashes from file names.
+@end table
+
+By default, GNU @code{tar} drops a leading @samp{/} on input or output.
+This option turns off this behavior; it is equivalent to changing to the
+root directory before running @code{tar} (except it also turns off the
+usual warning message).
+
+When @code{tar} extracts archive members from an archive, it strips any
+leading slashes (@samp{/}) from the member name. This causes absolute
+member names in the archive to be treated as relative file names. This
+allows you to have such members extracted wherever you want, instead of
+being restricted to extracting the member in the exact directory named
+in the archive. For example, if the archive member has the name
+@file{/etc/passwd}, @code{tar} will extract it as if the name were
+really @file{etc/passwd}.
+
+Other @code{tar} programs do not do this. As a result, if you create an
+archive whose member names start with a slash, they will be difficult
+for other people with a non-GNU @code{tar} program to use. Therefore,
+GNU @code{tar} also strips leading slashes from member names when
+putting members into the archive. For example, if you ask @code{tar} to
+add the file @file{/bin/ls} to an archive, it will do so, but the member
+name will be @file{bin/ls}.
+
+If you use the @value{op-absolute-names} option, @code{tar} will do
+neither of these transformations.
+
+To archive or extract files relative to the root directory, specify
+the @value{op-absolute-names} option.
+
+Normally, @code{tar} acts on files relative to the working
+directory---ignoring superior directory names when archiving, and
+ignoring leading slashes when extracting.
+
+When you specify @value{op-absolute-names}, @code{tar} stores file names
+including all superior directory names, and preserves leading slashes.
+If you only invoked @code{tar} from the root directory you would never
+need the @value{op-absolute-names} option, but using this option may be
+more convenient than switching to root.
+
+@FIXME{Should be an example in the tutorial/wizardry section using this
+to transfer files between systems.}
+
+@FIXME{Is write access an issue?}
+
+@table @kbd
+@item --absolute-names
+Preserves full file names (inclusing superior dirctory names) when
+archiving files. Preserves leading slash when extracting files.
+
+@end table
+
+@FIXME{this is still horrible; need to talk with dan on monday.}
+
+@code{tar} prints out a message about removing the @samp{/} from file
+names. This message appears once per GNU @code{tar} invocation. It
+represents something which ought to be told; ignoring what it means can
+cause very serious surprises, later.
+
+Some people, nevertheless, do not want to see this message. Wanting to
+play really dangerously, one may of course redirect @code{tar} standard
+error to the sink. For example, under @code{sh}:
+
+@example
+$ @kbd{tar -c -f archive.tar /home 2> /dev/null}
+@end example
+
+@noindent
+Another solution, both nicer and simpler, would be to change to
+the @file{/} directory first, and then avoid absolute notation.
+For example:
+
+@example
+$ @kbd{(cd / && tar -c -f archive.tar home)}
+$ @kbd{tar -c -f archive.tar -C / home}
+@end example
+
+@node Date input formats, Formats, Choosing, Top
+@chapter Date input formats
+
+@cindex date input formats
+@findex getdate
+
+@quotation
+Our units of temporal measurement, from seconds on up to months, are so
+complicated, asymmetrical and disjunctive so as to make coherent mental
+reckoning in time all but impossible. Indeed, had some tyrannical god
+contrived to enslave our minds to time, to make it all but impossible
+for us to escape subjection to sodden routines and unpleasant surprises,
+he could hardly have done better than handing down our present system.
+It is like a set of trapezoidal building blocks, with no vertical or
+horizontal surfaces, like a language in which the simplest thought
+demands ornate constructions, useless particles and lengthy
+circumlocutions. Unlike the more successful patterns of language and
+science, which enable us to face experience boldly or at least
+level-headedly, our system of temporal calculation silently and
+persistently encourages our terror of time.
+
+@dots{} It is as though architects had to measure length in feet, width
+in meters and height in ells; as though basic instruction manuals
+demanded a knowledge of five different languages. It is no wonder then
+that we often look into our own immediate past or future, last Tuesday
+or a week from Sunday, with feelings of helpless confusion. @dots{}
+
+--- Robert Grudin, @cite{Time and the Art of Living}.
+@end quotation
+
+This section describes the textual date representations that GNU
+programs accept. These are the strings you, as a user, can supply as
+arguments to the various programs. The C interface (via the
+@code{getdate} function) is not described here.
+
+@cindex beginning of time, for Unix
+@cindex epoch, for Unix
+Although the date syntax here can represent any possible time since zero
+A.D., computer integers are not big enough for such a (comparatively)
+long time. The earliest date semantically allowed on Unix systems is
+midnight, 1 January 1970 UCT.
+
+@menu
+* General date syntax:: Common rules.
+* Calendar date item:: 19 Dec 1994.
+* Time of day item:: 9:20pm.
+* Timezone item:: EST, DST, BST, UCT, AHST, ...
+* Day of week item:: Monday and others.
+* Relative item in date strings:: next tuesday, 2 years ago.
+* Pure numbers in date strings:: 19931219, 1440.
+* Authors of getdate:: Bellovin, Salz, Berets, et al.
+@end menu
+
+
+@node General date syntax, Calendar date item, Date input formats, Date input formats
+@section General date syntax
+
+@cindex general date syntax
+
+@cindex items in date strings
+A @dfn{date} is a string, possibly empty, containing many items
+separated by whitespace. The whitespace may be omitted when no
+ambiguity arises. The empty string means the beginning of today (i.e.,
+midnight). Order of the items is immaterial. A date string may contain
+many flavors of items:
+
+@itemize @bullet
+@item calendar date items
+@item time of the day items
+@item time zone items
+@item day of the week items
+@item relative items
+@item pure numbers.
+@end itemize
+
+@noindent We describe each of these item types in turn, below.
+
+@cindex numbers, written-out
+@cindex ordinal numbers
+@findex first @r{in date strings}
+@findex next @r{in date strings}
+@findex last @r{in date strings}
+A few numbers may be written out in words in most contexts. This is
+most useful for specifying day of the week items or relative items (see
+below). Here is the list: @samp{first} for 1, @samp{next} for 2,
+@samp{third} for 3, @samp{fourth} for 4, @samp{fifth} for 5,
+@samp{sixth} for 6, @samp{seventh} for 7, @samp{eighth} for 8,
+@samp{ninth} for 9, @samp{tenth} for 10, @samp{eleventh} for 11 and
+@samp{twelfth} for 12. Also, @samp{last} means exactly @math{-1}.
+
+@cindex months, written-out
+When a month is written this way, it is still considered to be written
+numerically, instead of being ``spelled in full''; this changes the
+allowed strings.
+
+@cindex case, ignored in dates
+@cindex comments, in dates
+Alphabetic case is completely ignored in dates. Comments may be introduced
+between round parentheses, as long as included parentheses are properly
+nested. Hyphens not followed by a digit are currently ignored. Leading
+zeros on numbers are ignored.
+
+
+@node Calendar date item, Time of day item, General date syntax, Date input formats
+@section Calendar date item
+
+@cindex calendar date item
+
+A @dfn{calendar date item} specifies a day of the year. It is
+specified differently, depending on whether the month is specified
+numerically or literally. All these strings specify the same calendar date:
+
+@example
+1970-09-17 # ISO 8601.
+70-9-17 # This century assumed by default.
+70-09-17 # Leading zeros are ignored.
+9/17/72 # Common U.S. writing.
+24 September 1972
+24 Sept 72 # September has a special abbreviation.
+24 Sep 72 # Three-letter abbreviations always allowed.
+Sep 24, 1972
+24-sep-72
+24sep72
+@end example
+
+The year can also be omitted. In this case, the last specified year is
+used, or the current year if none. For example:
+
+@example
+9/17
+sep 17
+@end example
+
+Here are the rules.
+
+@cindex ISO 8601 date format
+@cindex date format, ISO 8601
+For numeric months, the ISO 8601 format
+@samp{@var{year}-@var{month}-@var{day}} is allowed, where @var{year} is
+any positive number, @var{month} is a number between 01 and 12, and
+@var{day} is a number between 01 and 31. A leading zero must be present
+if a number is less than ten. If @var{year} is less than 100, then 1900
+is added to it to force a date in this century. The construct
+@samp{@var{month}/@var{day}/@var{year}}, popular in the United States,
+is accepted. Also @samp{@var{month}/@var{day}}, omitting the year.
+
+@cindex month names in date strings
+@cindex abbreviations for months
+Literal months may be spelled out in full: @samp{January},
+@samp{February}, @samp{March}, @samp{April}, @samp{May}, @samp{June},
+@samp{July}, @samp{August}, @samp{September}, @samp{October},
+@samp{November} or @samp{December}. Literal months may be abbreviated
+to their first three letters, possibly followed by an abbreviating dot.
+It is also permitted to write @samp{Sept} instead of @samp{September}.
+
+When months are written literally, the calendar date may be given as any
+of the following:
+
+@example
+@var{day} @var{month} @var{year}
+@var{day} @var{month}
+@var{month} @var{day} @var{year}
+@var{day}-@var{month}-@var{year}
+@end example
+
+Or, omitting the year:
+
+@example
+@var{month} @var{day}
+@end example
+
+
+@node Time of day item, Timezone item, Calendar date item, Date input formats
+@section Time of day item
+
+@cindex time of day item
+
+A @dfn{time of day item} in date strings specifies the time on a given
+day. Here are some examples, all of which represent the same time:
+
+@example
+20:02:0
+20:02
+8:02pm
+20:02-0500 # In EST (Eastern U.S. Standard Time).
+@end example
+
+More generally, the time of the day may be given as
+@samp{@var{hour}:@var{minute}:@var{second}}, where @var{hour} is
+a number between 0 and 23, @var{minute} is a number between 0 and
+59, and @var{second} is a number between 0 and 59. Alternatively,
+@samp{:@var{second}} can be omitted, in which case it is taken to
+be zero.
+
+@findex am @r{in date strings}
+@findex pm @r{in date strings}
+@findex midnight @r{in date strings}
+@findex noon @r{in date strings}
+If the time is followed by @samp{am} or @samp{pm} (or @samp{a.m.}
+or @samp{p.m.}), @var{hour} is restricted to run from 1 to 12, and
+@samp{:@var{minute}} may be omitted (taken to be zero). @samp{am}
+indicates the first half of the day, @samp{pm} indicates the second
+half of the day. In this notation, 12 is the predecessor of 1:
+midnight is @samp{12am} while noon is @samp{12pm}.
+
+@cindex timezone correction
+@cindex minutes, timezone correction by
+The time may alternatively be followed by a timezone correction,
+expressed as @samp{@var{s}@var{hh}@var{mm}}, where @var{s} is @samp{+}
+or @samp{-}, @var{hh} is a number of zone hours and @var{mm} is a number
+of zone minutes. When a timezone correction is given this way, it
+forces interpretation of the time in UTC, overriding any previous
+specification for the timezone or the local timezone. The @var{minute}
+part of the time of the day may not be elided when a timezone correction
+is used. This is the only way to specify a timezone correction by
+fractional parts of an hour.
+
+Either @samp{am}/@samp{pm} or a timezone correction may be specified,
+but not both.
+
+
+@node Timezone item, Day of week item, Time of day item, Date input formats
+@section Timezone item
+
+@cindex timezone item
+
+A @dfn{timezone item} specifies an international timezone, indicated by
+a small set of letters. Any included period is ignored. Military
+timezone designations use a single letter. Currently, only integral
+zone hours may be represented in a timezone item. See the previous
+section for a finer control over the timezone correction.
+
+Here are many non-daylight-savings-time timezones, indexed by the zone
+hour value.
+
+@table @asis
+@item +000
+@cindex Greenwich Mean Time
+@cindex Universal Coordinated Time
+@cindex Western European Time
+@samp{GMT} for Greenwich Mean, @samp{UT} or @samp{UTC} for Universal
+(Coordinated), @samp{WET} for Western European and @samp{Z} for
+militaries.
+@item +100
+@cindex West African Time
+@samp{WAT} for West Africa and
+@samp{A} for militaries.
+@item +200
+@cindex Azores Time
+@samp{AT} for Azores and @samp{B} for militaries.
+@item +300
+@samp{C} for militaries.
+@item +400
+@cindex Atlantic Standard Time
+@samp{AST} for Atlantic Standard and @samp{D} for militaries.
+@item +500
+@cindex Eastern Standard Time
+@samp{E} for militaries and @samp{EST} for Eastern Standard.
+@item +600
+@cindex Central Standard Time
+@samp{CST} for Central Standard and @samp{F} for militaries.
+@item +700
+@cindex Mountain Standard Time
+@samp{G} for militaries and @samp{MST} for Mountain Standard.
+@item +800
+@cindex Pacific Standard Time
+@samp{H} for militaries and @samp{PST} for Pacific Standard.
+@item +900
+@cindex Yukon Standard Time
+@samp{I} for militaries and @samp{YST} for Yukon Standard.
+@item +1000
+@cindex Alaska-Hawaii Time
+@cindex Central Alaska Time
+@cindex Hawaii Standard Time
+@samp{AHST} for Alaska-Hawaii Standard, @samp{CAT} for Central Alaska,
+@samp{HST} for Hawaii Standard and @samp{K} for militaries.
+@item +1100
+@cindex Nome Standard Time
+@samp{L} for militaries and @samp{NT} for Nome.
+@item +1200
+@cindex International Date Line West
+@samp{IDLW} for International Date Line West and @samp{M} for
+militaries.
+@item -100
+@cindex Central European Time
+@cindex Middle European Time
+@cindex Middle European Winter Time
+@cindex French Winter Time
+@cindex Swedish Winter Time
+@samp{CET} for Central European, @samp{FWT} for French Winter,
+@samp{MET} for Middle European, @samp{MEWT} for Middle European
+Winter, @samp{N} for militaries and @samp{SWT} for Swedish Winter.
+@item -200
+@cindex Eastern European Time
+@cindex USSR Zone
+@samp{EET} for Eastern European, USSR Zone 1 and @samp{O} for militaries.
+@item -300
+@cindex Baghdad Time
+@samp{BT} for Baghdad, USSR Zone 2 and @samp{P} for militaries.
+@item -400
+@samp{Q} for militaries and @samp{ZP4} for USSR Zone 3.
+@item -500
+@samp{R} for militaries and @samp{ZP5} for USSR Zone 4.
+@item -600
+@samp{S} for militaries and @samp{ZP6} for USSR Zone 5.
+@item -700
+@cindex West Australian Standard Time
+@samp{T} for militaries and @samp{WAST} for West Australian Standard.
+@item -800
+@cindex China Coast Time
+@samp{CCT} for China Coast, USSR Zone 7 and @samp{U} for militaries.
+@item -900
+@cindex Japan Standard Time
+@samp{JST} for Japan Standard, USSR Zone 8 and @samp{V} for militaries.
+@item -1000
+@cindex East Australian Standard Time
+@cindex Guam Standard Time
+@samp{EAST} for East Australian Standard, @samp{GST} for Guam
+Standard, USSR Zone 9 and @samp{W} for militaries.
+@item -1100
+@samp{X} for militaries.
+@item -1200
+@cindex International Date Line East
+@cindex New Zealand Standard Time
+@samp{IDLE} for International Date Line East, @samp{NZST} for
+New Zealand Standard, @samp{NZT} for New Zealand and @samp{Y} for
+militaries.
+@end table
+
+@cindex daylight savings time
+Here are many DST timezones, indexed by the zone hour value. Also, by
+following a non-DST timezone by the string @samp{DST} in a separate word
+(that is, separated by some whitespace), the corresponding DST timezone
+may be specified.
+
+@table @asis
+@item 0
+@samp{BST} for British Summer.
+@item +400
+@samp{ADT} for Atlantic Daylight.
+@item +500
+@samp{EDT} for Eastern Daylight.
+@item +600
+@samp{CDT} for Central Daylight.
+@item +700
+@samp{MDT} for Mountain Daylight.
+@item +800
+@samp{PDT} for Pacific Daylight.
+@item +900
+@samp{YDT} for Yukon Daylight.
+@item +1000
+@samp{HDT} for Hawaii Daylight.
+@item -100
+@samp{MEST} for Middle European Summer, @samp{MESZ} for Middle European
+Summer, @samp{SST} for Swedish Summer and @samp{FST} for French Summer.
+@item -700
+@samp{WADT} for West Australian Daylight.
+@item -1000
+@samp{EADT} for Eastern Australian Daylight.
+@item -1200
+@samp{NZDT} for New Zealand Daylight.
+@end table
+
+
+@node Day of week item, Relative item in date strings, Timezone item, Date input formats
+@section Day of week item
+
+@cindex day of week item
+
+The explicit mention of a day of the week will forward the date
+(only if necessary) to reach that day of the week in the future.
+
+Days of the week may be spelled out in full: @samp{Sunday},
+@samp{Monday}, @samp{Tuesday}, @samp{Wednesday}, @samp{Thursday},
+@samp{Friday} or @samp{Saturday}. Days may be abbreviated to their
+first three letters, optionally followed by a period. The special
+abbreviations @samp{Tues} for @samp{Tuesday}, @samp{Wednes} for
+@samp{Wednesday} and @samp{Thur} or @samp{Thurs} for @samp{Thursday} are
+also allowed.
+
+@findex next @var{day}
+@findex last @var{day}
+A number may precede a day of the week item to move forward
+supplementary weeks. It is best used in expression like @samp{third
+monday}. In this context, @samp{last @var{day}} or @samp{next
+@var{day}} is also acceptable; they move one week before or after
+the day that @var{day} by itself would represent.
+
+A comma following a day of the week item is ignored.
+
+
+@node Relative item in date strings, Pure numbers in date strings, Day of week item, Date input formats
+@section Relative item in date strings
+
+@cindex relative items in date strings
+@cindex displacement of dates
+
+@dfn{Relative items} adjust a date (or the current date if none) forward
+or backward. The effects of relative items accumulate. Here are some
+examples:
+
+@example
+1 year
+1 year ago
+3 years
+2 days
+@end example
+
+@findex year @r{in date strings}
+@findex month @r{in date strings}
+@findex fortnight @r{in date strings}
+@findex week @r{in date strings}
+@findex day @r{in date strings}
+@findex hour @r{in date strings}
+@findex minute @r{in date strings}
+The unit of time displacement may be selected by the string @samp{year}
+or @samp{month} for moving by whole years or months. These are fuzzy
+units, as years and months are not all of equal duration. More precise
+units are @samp{fortnight} which is worth 14 days, @samp{week} worth 7
+days, @samp{day} worth 24 hours, @samp{hour} worth 60 minutes,
+@samp{minute} or @samp{min} worth 60 seconds, and @samp{second} or
+@samp{sec} worth one second. An @samp{s} suffix on these units is
+accepted and ignored.
+
+@findex ago @r{in date strings}
+The unit of time may be preceded by a multiplier, given as an optionally
+signed number. Unsigned numbers are taken as positively signed. No
+number at all implies 1 for a multiplier. Following a relative item by
+the string @samp{ago} is equivalent to preceding the unit by a
+multiplicator with value @math{-1}.
+
+@findex day @r{in date strings}
+@findex tomorrow @r{in date strings}
+@findex yesterday @r{in date strings}
+The string @samp{tomorrow} is worth one day in the future (equivalent
+to @samp{day}), the string @samp{yesterday} is worth
+one day in the past (equivalent to @samp{day ago}).
+
+@findex now @r{in date strings}
+@findex today @r{in date strings}
+@findex this @r{in date strings}
+The strings @samp{now} or @samp{today} are relative items corresponding
+to zero-valued time displacement, these strings come from the fact
+a zero-valued time displacement represents the current time when not
+otherwise change by previous items. They may be used to stress other
+items, like in @samp{12:00 today}. The string @samp{this} also has
+the meaning of a zero-valued time displacement, but is preferred in
+date strings like @samp{this thursday}.
+
+When a relative item makes the resulting date to cross the boundary
+between DST and non-DST (or vice-versa), the hour is adjusted according
+to the local time.
+
+
+@node Pure numbers in date strings, Authors of getdate, Relative item in date strings, Date input formats
+@section Pure numbers in date strings
+
+@cindex pure numbers in date strings
+
+The precise intepretation of a pure decimal number is dependent of
+the context in the date string.
+
+If the decimal number is of the form @var{yyyy}@var{mm}@var{dd} and no
+other calendar date item (@pxref{Calendar date item}) appears before it
+in the date string, then @var{yyyy} is read as the year, @var{mm} as the
+month number and @var{dd} as the day of the month, for the specified
+calendar date.
+
+If the decimal number is of the form @var{hh}@var{mm} and no other time
+of day item appears before it in the date string, then @var{hh} is read
+as the hour of the day and @var{mm} as the minute of the hour, for the
+specified time of the day. @var{mm} can also be omitted.
+
+If both a calendar date and a time of day appear to the left of a number
+in the date string, but no relative item, then the number overrides the
+year.
+
+
+@node Authors of getdate, , Pure numbers in date strings, Date input formats
+@section Authors of @code{getdate}
+
+@cindex authors of @code{getdate}
+
+@cindex Bellovin, Steven M.
+@cindex Salz, Rich
+@cindex Berets, Jim
+@cindex MacKenzie, David
+@cindex Meyering, Jim
+@code{getdate} was originally implemented by Steven M. Bellovin
+(@samp{smb@@research.att.com}) while at the University of North Carolina
+at Chapel Hill. The code was later tweaked by a couple of people on
+Usenet, then completely overhauled by Rich $alz (@samp{rsalz@@bbn.com})
+and Jim Berets (@samp{jberets@@bbn.com}) in August, 1990. Various
+revisions for the GNU system were made by David MacKenzie, Jim Meyering,
+and others.
+
+@cindex Pinard, F.
+@cindex Berry, K.
+This chapter was originally produced by Fran@,{c}ois Pinard
+(@samp{pinard@@iro.umontreal.ca}) from the @file{getdate.y} source code,
+and then edited by K.@: Berry (@samp{kb@@cs.umb.edu}).
+
+@node Formats, Media, Date input formats, Top
+@chapter Controlling the Archive Format
+
+@FIXME{need an intro here}
+
+@menu
+* Portability:: Making @code{tar} Archives More Portable
+* Compression:: Using Less Space through Compression
+* Attributes:: Handling File Attributes
+* Standard:: The Standard Format
+* Extensions:: GNU Extensions to the Archive Format
+* cpio:: Comparison of @code{tar} and @code{cpio}
+@end menu
+
+@node Portability, Compression, Formats, Formats
+@section Making @code{tar} Archives More Portable
+
+Creating a @code{tar} archive on a particular system that is meant to be
+useful later on many other machines and with other versions of @code{tar}
+is more challenging than you might think. @code{tar} archive formats
+have been evolving since the first versions of Unix. Many such formats
+are around, and are not always comptible with each other. This section
+discusses a few problems, and gives some advice about making @code{tar}
+archives more portable.
+
+One golden rule is simplicity. For example, limit your @code{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
+* posix:: POSIX archives
+* Checksumming:: Checksumming Problems
+@end menu
+
+@node Portable Names, dereference, Portability, Portability
+@subsection Portable Names
+
+Use @emph{straight} file and directory names, made up of printable
+ASCII characters, avoiding colons, slashes, backslashes, spaces, and
+other @emph{dangerous} characters. Avoid deep directory nesting.
+Accounting for oldish System V machines, limit your file and directory
+names to 14 characters or less.
+
+If you intend to have your @code{tar} archives to be read under MSDOS,
+you should not rely on case distinction for file names, and you might
+use the GNU @code{doschk} program for helping you further diagnosing
+illegal MSDOS names, which are even more limited than System V's.
+
+@node dereference, old, Portable Names, Portability
+@subsection Symbolic Links
+@cindex File names, using symbolic links
+@cindex Symbolic link as file name
+
+Normally, when @code{tar} archives a symbolic link, it writes a
+block to the archive naming the target of the link. In that way, the
+@code{tar} archive is a faithful record of the filesystem contents.
+@value{op-dereference} is used with @value{op-create}, and causes @code{tar}
+to archive the files symbolic links point to, instead of the links
+themselves. When this option is used, when @code{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 @code{tar}, an extracted file
+might be linked to a file name that no longer exists in the file