@end ifnottex
@c The master menu, created with texinfo-master-menu, goes here.
-@c (However, getdate.texi's menu is interpolated by hand.)
+@c FIXME: Submenus for getdate.texi and intern.texi are interpolated by hand.
@menu
* Introduction::
* Changes::
* Configuring Help Summary::
* Genfile::
-* Snapshot Files::
+* Tar Internals::
* Free Software Needs Free Documentation::
* Copying This Manual::
* Index of Command Line Options::
* extracting archives::
* extracting files::
* extract dir::
+* extracting untrusted archives::
* failing commands::
Invoking @GNUTAR{}
* Recursive Unlink::
* Data Modification Times::
* Setting Access Permissions::
+* Directory Modification Times and Permissions::
* Writing to Standard Output::
+* Writing to an External Program::
* remove files::
Coping with Scarce Resources
* Selecting Archive Members::
* files:: Reading Names from a File
* exclude:: Excluding Some Files
-* Wildcards:: Wildcards Patterns and Matching
+* wildcards:: Wildcards Patterns and Matching
+* quoting styles:: Ways of Quoting Special Characters in Names
+* transform:: Modifying File and Member Names
* after:: Operating Only on New Files
* recurse:: Descending into Directories
* one:: Crossing File System Boundaries
* problems with exclude::
+Wildcards Patterns and Matching
+
+* controlling pattern-matching::
+
Crossing File System Boundaries
* directory:: Changing Directory
* absolute:: Absolute File Names
+Controlling the Archive Format
+
+* Portability:: Making @command{tar} Archives More Portable
+* Compression:: Using Less Space through Compression
+* Attributes:: Handling File Attributes
+* cpio:: Comparison of @command{tar} and @command{cpio}
+
Date input formats
* General date syntax:: Common rules.
* Seconds since the Epoch:: @@1078100502.
* Authors of get_date:: Bellovin, Eggert, Salz, Berets, et al.
-Controlling the Archive Format
-
-* Portability:: Making @command{tar} Archives More Portable
-* Compression:: Using Less Space through Compression
-* Attributes:: Handling File Attributes
-* Standard:: The Standard Format
-* Extensions:: @acronym{GNU} Extensions to the Archive Format
-* cpio:: Comparison of @command{tar} and @command{cpio}
-
Making @command{tar} Archives More Portable
* Portable Names:: Portable Names
* dereference:: Symbolic Links
* old:: Old V7 Archives
+* ustar:: Ustar Archives
+* gnu:: GNU and old GNU format archives.
* posix:: @acronym{POSIX} archives
* Checksumming:: Checksumming Problems
* Large or Negative Values:: Large files, negative time stamps, etc.
+@GNUTAR{} and @acronym{POSIX} @command{tar}
+
+* PAX keywords:: Controlling Extended Header Keywords.
+
Using Less Space through Compression
* gzip:: Creating and Reading Compressed Archives
GNU tar internals and development
* Genfile::
+* Tar Internals::
+* Standard::
+* Extensions::
* Snapshot Files::
+* Dumpdir::
Copying This Manual
-* Free Software Needs Free Documentation::
* GNU Free Documentation License:: License for copying this manual
@end detailmenu
Fran@,{c}ois Pinard put version 1.11.8 of the manual together by
taking information from all these sources and merging them. Melissa
Weisshaus finally edited and redesigned the book to create version
-1.12. @FIXME{update version number as necessary; i'm being
-optimistic!} @FIXME{Someone [maybe karl berry? maybe bob chassell?
-maybe melissa? maybe julie sussman?] needs to properly index the
-thing.}
+1.12. The book for versions from 1.14 up to @value{VERSION} were edited
+by the current maintainer, Sergey Poznyakoff.
For version 1.12, Daniel Hagerty contributed a great deal of technical
consulting. In particular, he is the primary author of @ref{Backups}.
clear, and we will give many examples both using and not using
@option{--verbose} to show the differences.
-Sometimes, a single instance of @option{--verbose} on the command line
-will show a full, @samp{ls} style listing of an archive or files,
-giving sizes, owners, and similar information. @FIXME{Describe the
-exact output format, e.g., how hard links are displayed.}
-Other times, @option{--verbose} will only show files or members that the particular
-operation is operating on at the time. In the latter case, you can
-use @option{--verbose} twice in a command to get a listing such as that
-in the former case. For example, instead of saying
+Each instance of @option{--verbose} on the command line increases the
+verbosity level by one, so if you need more details on the output,
+specify it twice.
+
+When reading archives (@option{--list}, @option{--extract},
+@option{--diff}), @command{tar} by default prints only the names of
+the members being extracted. Using @option{--verbose} will show a full,
+@command{ls} style member listing.
+
+In contrast, when writing archives (@option{--create}, @option{--append},
+@option{--update}), @command{tar} does not print file names by
+default. So, a single @option{--verbose} option shows the file names
+being added to the archive, while two @option{--verbose} options
+enable the full listing.
+
+For example, to create an archive in verbose mode:
@smallexample
-@kbd{tar -cvf afiles.tar apple angst aspic}
+$ @kbd{tar -cvf afiles.tar apple angst aspic}
+apple
+angst
+aspic
@end smallexample
@noindent
-above, you might say
+Creating the same archive with the verbosity level 2 could give:
@smallexample
-@kbd{tar -cvvf afiles.tar apple angst aspic}
+$ @kbd{tar -cvvf afiles.tar apple angst aspic}
+-rw-r--r-- gray/staff 62373 2006-06-09 12:06 apple
+-rw-r--r-- gray/staff 11481 2006-06-09 12:06 angst
+-rw-r--r-- gray/staff 23152 2006-06-09 12:06 aspic
@end smallexample
@noindent
Later in the tutorial, we will give examples using @w{@option{--verbose
--verbose}}.
+The full output consists of six fields:
+
+@itemize @bullet
+@item File type and permissions in symbolic form.
+These are displayed in the same format as the first column of
+@command{ls -l} output (@pxref{What information is listed,
+format=verbose, Verbose listing, fileutils, GNU file utilities}).
+
+@item Owner name and group separated by a slash character.
+If these data are not available (for example, when listing a @samp{v7} format
+archive), numeric ID values are printed instead.
+
+@item Size of the file, in bytes.
+
+@item File modification date in ISO 8601 format.
+
+@item File modification time.
+
+@item File name.
+If the name contains any special characters (white space, newlines,
+etc.) these are displayed in an unambiguous form using so called
+@dfn{quoting style}. For the detailed discussion of available styles
+and on how to use them, see @ref{quoting styles}.
+
+Depending on the file type, the name can be followed by some
+additional information, described in the following table:
+
+@table @samp
+@item -> @var{link-name}
+The file or archive member is a @dfn{symbolic link} and
+@var{link-name} is the name of file it links to.
+
+@item link to @var{link-name}
+The file or archive member is a @dfn{hard link} and @var{link-name} is
+the name of file it links to.
+
+@item --Long Link--
+The archive member is an old GNU format long link. You will normally
+not encounter this.
+
+@item --Long Name--
+The archive member is an old GNU format long name. You will normally
+not encounter this.
+
+@item --Volume Header--
+The archive member is a GNU @dfn{volume header} (@pxref{Tape Files}).
+
+@item --Continued at byte @var{n}--
+Encountered only at the beginning of a multy-volume archive
+(@pxref{Using Multiple Tapes}). This archive member is a continuation
+from the previous volume. The number @var{n} gives the offset where
+the original file was split.
+
+@item --Mangled file names--
+This archive member contains @dfn{mangled file names} declarations,
+a special member type that was used by early versions of @GNUTAR{}.
+You probably will never encounter this, unless you are reading a very
+old archive.
+
+@item unknown file type @var{c}
+An archive member of unknown type. @var{c} is the type character from
+the archive header. If you encounter such a message, it means that
+either your archive contains proprietary member types @GNUTAR{} is not
+able to handle, or the archive is corrupted.
+@end table
+
+@end itemize
+
+For example, here is an archive listing containing most of the special
+suffixes explained above:
+
+@smallexample
+@group
+V--------- 0/0 1536 2006-06-09 13:07 MyVolume--Volume Header--
+-rw-r--r-- gray/staff 456783 2006-06-09 12:06 aspic--Continued at
+byte 32456--
+-rw-r--r-- gray/staff 62373 2006-06-09 12:06 apple
+lrwxrwxrwx gray/staff 0 2006-06-09 13:01 angst -> apple
+-rw-r--r-- gray/staff 35793 2006-06-09 12:06 blues
+hrw-r--r-- gray/staff 0 2006-06-09 12:06 music link to blues
+@end group
+@end smallexample
+
+@smallexample
+@end smallexample
+
@node help tutorial
@unnumberedsubsec Getting Help: Using the @option{--help} Option
(@file{collection.tar}), and @option{--file} is the option which lets
you give it the name you chose. The files, @file{blues}, @file{folk},
and @file{jazz}, are now members of the archive, @file{collection.tar}
-(they are @dfn{file name arguments} to the @option{--create} operation).
-@FIXME{xref here to the discussion of file name args?}Now that they are
+(they are @dfn{file name arguments} to the @option{--create} operation.
+@xref{Choosing}, for the detailed discussion on these.) Now that they are
in the archive, they are called @emph{archive members}, not files.
(@pxref{Definitions,members}).
@end smallexample
@noindent
-will list all members whose name contains @samp{b}. @xref{Wildcards},
+will list all members whose name contains @samp{b}. @xref{wildcards},
for a detailed discussion of globbing patterns and related
@command{tar} command line options.
command line arguments as globbing patterns and @option{--no-anchored}
informs it that the patterns apply to member names after any @samp{/}
delimiter. The use of globbing patterns is discussed in detail in
-@xref{Wildcards}.
+@xref{wildcards}.
You can extract a file to standard output by combining the above options
with the @option{--to-stdout} (@option{-O}) option (@pxref{Writing to Standard
The distinction between file names and archive member names is especially
important when shell globbing is used, and sometimes a source of confusion
-for newcomers. @xref{Wildcards}, for more information about globbing.
+for newcomers. @xref{wildcards}, for more information about globbing.
The problem is that shells may only glob using existing files in the
file system. Only @command{tar} itself may glob on archive members, so when
needed, you must ensure that wildcard characters reach @command{tar} without
@code{bzip2}. @xref{gzip}.
@opindex checkpoint, summary
-@item --checkpoint
+@item --checkpoint[=@var{number}]
-This option directs @command{tar} to print periodic checkpoint messages as it
-reads through the archive. It is intended for when you want a visual
-indication that @command{tar} is still running, but don't want to see
-@option{--verbose} output. @FIXME-xref{}
+This option directs @command{tar} to print periodic checkpoint
+messages as it reads through the archive. It is intended for when you
+want a visual indication that @command{tar} is still running, but
+don't want to see @option{--verbose} output. For a detailed
+description, see @ref{Progress information}.
@opindex check-links, summary
@item --check-links
dumped for each processed file. If this number does not match the
total number of hard links for the file, a warning message will be
output @footnote{Earlier versions of @GNUTAR{} understood @option{-l} as a
-synonym for @option{--one-file-system}. The current semantics, wich
+synonym for @option{--one-file-system}. The current semantics, which
complies to UNIX98, was introduced with version
1.15.91. @xref{Changes}, for more information.}.
@opindex no-quote-chars, summary
@item --no-quote-chars=@var{string}
-Do not quote characters from @var{string}, even if the selected
-quoting style implies they should be quoted (@FIXME-pxref{Quoting Styles}).
+Remove characters listed in @var{string} from the list of quoted
+characters set by the previous @option{--quote-chars} option
+(@pxref{quoting styles}).
@opindex no-recursion, summary
@item --no-recursion
This option does not affect extraction from archives.
+@opindex transform, summary
+@item --transform=@var{sed-expr}
+
+Transform file or member names using @command{sed} replacement expression
+@var{sed-expr}. For example,
+
+@smallexample
+$ @kbd{tar cf archive.tar --transform 's,^\./,usr/,' .}
+@end smallexample
+
+@noindent
+will add to @file{archive} files from the current working directory,
+replacing initial @samp{./} prefix with @samp{usr/}. For the detailed
+discussion, @xref{transform}.
+
+To see transformed member names in verbose listings, use
+@option{--show-transformed-names} option
+(@pxref{show-transformed-names}).
+
@opindex quote-chars, summary
@item --quote-chars=@var{string}
Always quote characters from @var{string}, even if the selected
-quoting style would not quote them (@FIXME-pxref{Quoting Styles}).
+quoting style would not quote them (@pxref{quoting styles}).
@opindex quoting-style, summary
@item --quoting-style=@var{style}
Set quoting style to use when printing member and file names
-(@FIXME-pxref{Quoting Styles}). Valid @var{style} values are:
+(@pxref{quoting styles}). Valid @var{style} values are:
@code{literal}, @code{shell}, @code{shell-always}, @code{c},
@code{escape}, @code{locale}, and @code{clocale}. Default quoting
style is @code{escape}, unless overridden while configuring the
@opindex pax-option, summary
@item --pax-option=@var{keyword-list}
-@FIXME{Such a detailed description does not belong there, move it elsewhere.}
This option is meaningful only with @acronym{POSIX.1-2001} archives
(@pxref{posix}). It modifies the way @command{tar} handles the
extended header keywords. @var{Keyword-list} is a comma-separated
-list of keyword options, each keyword option taking one of
-the following forms:
-
-@table @asis
-@item delete=@var{pattern}
-When used with one of archive-creation commands,
-this option instructs @command{tar} to omit from extended header records
-that it produces any keywords matching the string @var{pattern}.
-
-When used in extract or list mode, this option instructs tar
-to ignore any keywords matching the given @var{pattern} in the extended
-header records. In both cases, matching is performed using the pattern
-matching notation described in @acronym{POSIX 1003.2}, 3.13
-(See @cite{glob(7)}). For example:
-
-@smallexample
---pax-option delete=security.*
-@end smallexample
-
-would suppress security-related information.
-
-@item exthdr.name=@var{string}
-
-This keyword allows user control over the name that is written into the
-ustar header blocks for the extended headers. The name is obtained
-from @var{string} after making the following substitutions:
-
-@multitable @columnfractions .30 .70
-@headitem Meta-character @tab Replaced By
-@item %d @tab The directory name of the file, equivalent to the
-result of the @command{dirname} utility on the translated pathname.
-@item %f @tab The filename of the file, equivalent to the result
-of the @command{basename} utility on the translated pathname.
-@item %p @tab The process ID of the @command{tar} process.
-@item %% @tab A @samp{%} character.
-@end multitable
-
-Any other @samp{%} characters in @var{string} produce undefined
-results.
-
-If no option @samp{exthdr.name=string} is specified, @command{tar}
-will use the following default value:
-
-@smallexample
-%d/PaxHeaders.%p/%f
-@end smallexample
-
-@item globexthdr.name=@var{string}
-This keyword allows user control over the name that is written into
-the ustar header blocks for global extended header records. The name
-is obtained from the contents of @var{string}, after making
-the following substitutions:
-
-@multitable @columnfractions .30 .70
-@headitem Meta-character @tab Replaced By
-@item %n @tab An integer that represents the
-sequence number of the global extended header record in the archive,
-starting at 1.
-@item %p @tab The process ID of the @command{tar} process.
-@item %% @tab A @samp{%} character.
-@end multitable
-
-Any other @samp{%} characters in @var{string} produce undefined results.
-
-If no option @samp{globexthdr.name=string} is specified, @command{tar}
-will use the following default value:
-
-@smallexample
-$TMPDIR/GlobalHead.%p.%n
-@end smallexample
-
-@noindent
-where @samp{$TMPDIR} represents the value of the @var{TMPDIR}
-environment variable. If @var{TMPDIR} is not set, @command{tar}
-uses @samp{/tmp}.
-
-@item @var{keyword}=@var{value}
-When used with one of archive-creation commands, these keyword/value pairs
-will be included at the beginning of the archive in a global extended
-header record. When used with one of archive-reading commands,
-@command{tar} will behave as if it has encountered these keyword/value
-pairs at the beginning of the archive in a global extended header
-record.
-
-@item @var{keyword}:=@var{value}
-When used with one of archive-creation commands, these keyword/value pairs
-will be included as records at the beginning of an extended header for
-each file. This is effectively equivalent to @var{keyword}=@var{value}
-form except that it creates no global extended header records.
-
-When used with one of archive-reading commands, @command{tar} will
-behave as if these keyword/value pairs were included as records at the
-end of each extended header; thus, they will override any global or
-file-specific extended header record keywords of the same names.
-For example, in the command:
-
-@smallexample
-tar --format=posix --create \
- --file archive --pax-option gname:=user .
-@end smallexample
-
-the group name will be forced to a new value for all files
-stored in the archive.
-@end table
+list of keyword options. @xref{PAX keywords}, for a detailed
+discussion.
@opindex portability, summary
@item --portability
Instructs @command{tar} to mention directories its skipping over when
operating on a @command{tar} archive. @xref{show-omitted-dirs}.
+@opindex show-transformed-names, summary
@opindex show-stored-names, summary
-@item --show-stored-names
+@item --show-transformed-names
+@itemx --show-stored-names
-This option has effect only when used in conjunction with one of
-archive creation operations. It instructs tar to list the member names
+Display file or member names after applying any transformations
+(@pxref{transform}). In particular, when used in conjunction with one of
+archive creation operations it instructs tar to list the member names
stored in the archive, as opposed to the actual file
names. @xref{listing member and file names}.
@end smallexample
@noindent
-would extracted this file to file @file{name}.
+would extract this file to file @file{name}.
@opindex suffix, summary
@item --suffix=@var{suffix}
@option{--create} (@option{-c})---causes @command{tar} to print the total
amount written to the archive, after it has been fully created.
+@anchor{Progress information}
@cindex Progress information
@opindex checkpoint
The @option{--checkpoint} option prints an occasional message
-as @command{tar} reads or writes the archive. In fact, it prints
-a message each 10 records read or written. It is designed for
+as @command{tar} reads or writes the archive. It is designed for
those who don't need the more detailed (and voluminous) output of
@option{--block-number} (@option{-R}), but do want visual confirmation
-that @command{tar} is actually making forward progress.
+that @command{tar} is actually making forward progress. By default it
+prints a message each 10 records read or written. This can be changed
+by giving it a numeric argument after an equal sign:
-@FIXME{There is some confusion here. It seems that -R once wrote a
-message at @samp{every} record read or written.}
+@smallexample
+$ @kbd{tar -c --checkpoint=1000} /var
+tar: Write checkpoint 1000
+tar: Write checkpoint 2000
+tar: Write checkpoint 3000
+@end smallexample
+
+This example shows the default checkpoint message used by
+@command{tar}. If you place a dot immediately after the equal
+sign, it will print a @samp{.} at each checkpoint. For example:
+
+@smallexample
+$ @kbd{tar -c --checkpoint=.1000} /var
+...
+@end smallexample
@opindex show-omitted-dirs
@anchor{show-omitted-dirs}
to be printed for each directory in the archive which is skipped.
This happens regardless of the reason for skipping: the directory might
not have been named on the command line (implicitly or explicitly),
-it might be excluded by the use of the @option{--exclude=@var{pattern}} option, or
-some other reason.
+it might be excluded by the use of the
+@option{--exclude=@var{pattern}} option, or some other reason.
@opindex block-number
@cindex Block number where error occurred
tar: funk not found in archive
@end smallexample
-The spirit behind the @option{--compare} (@option{--diff}, @option{-d}) option is to check whether the
-archive represents the current state of files on disk, more than validating
-the integrity of the archive media. For this later goal, @xref{verify}.
+The spirit behind the @option{--compare} (@option{--diff},
+@option{-d}) option is to check whether the archive represents the
+current state of files on disk, more than validating the integrity of
+the archive media. For this later goal, @xref{verify}.
@node create options
@section Options Used by @option{--create}
where @var{x} is a letter describing the status of the file: @samp{Y}
if the file is present in the archive, @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).@FIXME-xref{dumpdir format}. Each such
+is included in the archive). @xref{Dumpdir}, for the detailed
+description of dumpdirs and status codes. Each such
line is terminated by a newline character. The last line is followed
by an additional newline to indicate the end of the data.
Script to be run when it's time to insert a new tape in for the next
volume. Administrators may want to tailor this script for their site.
-If this variable isn't set, @GNUTAR{} will display its built-in prompt
-@FIXME-xref{describe it somewhere!}, and will expect confirmation from
-the console.
+If this variable isn't set, @GNUTAR{} will display its built-in
+prompt, and will expect confirmation from the console.
+
+The built-in prompt for POSIX locale is:
+
+@smallexample
+Prepare volume #@var{n} for `@var{archive}' and hit return:
+@end smallexample
+
+@noindent
+where @var{n} is the ordinal number of the volume to be created and
+@var{archive} is archive file or device name.
+
+If you run @GNUTAR{} under a different locale, the translation of
+the above prompt to the locale's language will be used.
+
@end defvr
@defvr {Backup variable} SLEEP_MESSAGE
* Selecting Archive Members::
* files:: Reading Names from a File
* exclude:: Excluding Some Files
-* Wildcards:: Wildcards Patterns and Matching
+* wildcards:: Wildcards Patterns and Matching
+* quoting styles:: Ways of Quoting Special Characters in Names
+* transform:: Modifying File and Member Names
* after:: Operating Only on New Files
* recurse:: Descending into Directories
* one:: Crossing File System Boundaries
@end itemize
-@node Wildcards
+@node wildcards
@section Wildcards Patterns and Matching
@dfn{Globbing} is the operation by which @dfn{wildcard} characters,
literally @footnote{Notice that earlier @GNUTAR{} versions used
globbing for inclusion members, which contradicted to UNIX98
specification and was not documented. @xref{Changes}, for more
-information on this and other changes} and exclusion members are
+information on this and other changes.} and exclusion members are
treated as globbing patterns. For example:
@smallexample
--ignore-case --exclude='makefile' --no-ignore-case ---exclude='readme'
@end smallexample
+@noindent
ignores case when excluding @samp{makefile}, but not when excluding
@samp{readme}.
@item Exclusion @tab @option{--wildcards --no-anchored --wildcards-match-slash}
@end multitable
+@node quoting styles
+@section Quoting Member Names
+
+When displaying member names, @command{tar} takes care to avoid
+ambiguities caused by certain characters. This is called @dfn{name
+quoting}. The characters in question are:
+
+@itemize @bullet
+@item Non-printable control characters:
+
+@multitable @columnfractions 0.20 0.10 0.60
+@headitem Character @tab ASCII @tab Character name
+@item \a @tab 7 @tab Audible bell
+@item \b @tab 8 @tab Backspace
+@item \f @tab 12 @tab Form feed
+@item \n @tab 10 @tab New line
+@item \r @tab 13 @tab Carriage return
+@item \t @tab 9 @tab Horizontal tabulation
+@item \v @tab 11 @tab Vertical tabulation
+@end multitable
+
+@item Space (ASCII 32)
+
+@item Single and double quotes (@samp{'} and @samp{"})
+
+@item Backslash (@samp{\})
+@end itemize
+
+The exact way @command{tar} uses to quote these characters depends on
+the @dfn{quoting style}. The default quoting style, called
+@dfn{escape} (see below), uses backslash notation to represent control
+characters, space and backslash. Using this quoting style, control
+characters are represented as listed in column @samp{Character} in the
+above table, a space is printed as @samp{\ } and a backslash as @samp{\\}.
+
+@GNUTAR{} offers seven distinct quoting styles, which can be selected
+using @option{--quoting-style} option:
+
+@table @option
+@item --quoting-style=@var{style}
+@opindex quoting-style
+
+Sets quoting style. Valid values for @var{style} argument are:
+literal, shell, shell-always, c, escape, locale, clocale.
+@end table
+
+These styles are described in detail below. To illustrate their
+effect, we will use an imaginary tar archive @file{arch.tar}
+containing the following members:
+
+@smallexample
+@group
+# 1. Contains horizontal tabulation character.
+a tab
+# 2. Contains newline character
+a
+newline
+# 3. Contains a space
+a space
+# 4. Contains double quotes
+a"double"quote
+# 5. Contains single quotes
+a'single'quote
+# 6. Contains a backslash character:
+a\backslash
+@end group
+@end smallexample
+
+Here is how usual @command{ls} command would have listed them, if they
+had existed in the current working directory:
+
+@smallexample
+@group
+$ @kbd{ls}
+a\ttab
+a\nnewline
+a\ space
+a"double"quote
+a'single'quote
+a\\backslash
+@end group
+@end smallexample
+
+Quoting styles:
+
+@table @samp
+@item literal
+No quoting, display each character as is:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=literal}
+./
+./a space
+./a'single'quote
+./a"double"quote
+./a\backslash
+./a tab
+./a
+newline
+@end group
+@end smallexample
+
+@item shell
+Display characters the same way Bourne shell does:
+control characters, except @samp{\t} and @samp{\n}, are printed using
+backslash escapes, @samp{\t} and @samp{\n} are printed as is, and a
+single quote is printed as @samp{\'}. If a name contains any quoted
+characters, it is enclosed in single quotes. In particular, if a name
+contains single quotes, it is printed as several single-quoted strings:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=shell}
+./
+'./a space'
+'./a'\''single'\''quote'
+'./a"double"quote'
+'./a\backslash'
+'./a tab'
+'./a
+newline'
+@end group
+@end smallexample
+
+@item shell-always
+Same as @samp{shell}, but the names are always enclosed in single
+quotes:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=shell-always}
+'./'
+'./a space'
+'./a'\''single'\''quote'
+'./a"double"quote'
+'./a\backslash'
+'./a tab'
+'./a
+newline'
+@end group
+@end smallexample
+
+@item c
+Use the notation of the C programming language. All names are
+enclosed in double quotes. Control characters are quoted using
+backslash notations, double quotes are represented as @samp{\"},
+backslash characters are represented as @samp{\\}. Single quotes and
+spaces are not quoted:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=c}
+"./"
+"./a space"
+"./a'single'quote"
+"./a\"double\"quote"
+"./a\\backslash"
+"./a\ttab"
+"./a\nnewline"
+@end group
+@end smallexample
+
+@item escape
+Control characters are printed using backslash notation, a space is
+printed as @samp{\ } and a backslash as @samp{\\}. This is the
+default quoting style, unless it was changed when configured the
+package.
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=escape}
+./
+./a space
+./a'single'quote
+./a"double"quote
+./a\\backslash
+./a\ttab
+./a\nnewline
+@end group
+@end smallexample
+
+@item locale
+Control characters, single quote and backslash are printed using
+backslash notation. All names are quoted using left and right
+quotation marks, appropriate to the current locale. If it does not
+define quotation marks, use @samp{`} as left and @samp{'} as right
+quotation marks. Any occurrences of the right quotation mark in a
+name are escaped with @samp{\}, for example:
+
+For example:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=locale}
+`./'
+`./a space'
+`./a\'single\'quote'
+`./a"double"quote'
+`./a\\backslash'
+`./a\ttab'
+`./a\nnewline'
+@end group
+@end smallexample
+
+@item clocale
+Same as @samp{locale}, but @samp{"} is used for both left and right
+quotation marks, if not provided by the currently selected locale:
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=clocale}
+"./"
+"./a space"
+"./a'single'quote"
+"./a\"double\"quote"
+"./a\\backslash"
+"./a\ttab"
+"./a\nnewline"
+@end group
+@end smallexample
+@end table
+
+You can specify which characters should be quoted in addition to those
+implied by the current quoting style:
+
+@table @option
+@item --quote-chars=@var{string}
+Always quote characters from @var{string}, even if the selected
+quoting style would not quote them.
+@end table
+
+For example, using @samp{escape} quoting (compare with the usual
+escape listing above):
+
+@smallexample
+@group
+$ @kbd{tar tf arch.tar --quoting-style=escape --quote-chars=' "'}
+./
+./a\ space
+./a'single'quote
+./a\"double\"quote
+./a\\backslash
+./a\ttab
+./a\nnewline
+@end group
+@end smallexample
+
+To disable quoting of such additional characters, use the following
+option:
+
+@table @option
+@item --no-quote-chars=@var{string}
+Remove characters listed in @var{string} from the list of quoted
+characters set by the previous @option{--quote-chars} option.
+@end table
+
+This option is particularly useful if you have added
+@option{--quote-chars} to your @env{TAR_OPTIONS} (@pxref{TAR_OPTIONS})
+and wish to disable it for the current invocation.
+
+Note, that @option{--no-quote-chars} does @emph{not} disable those
+characters that are quoted by default in the selected quoting style.
+
+@node transform
+@section Modifying File and Member Names
+
+@command{Tar} archives contain detailed information about files stored
+in them and full file names are part of that information. When
+storing file to an archive, its file name is recorded in the archive
+along with the actual file contents. When restoring from an archive,
+a file is created on disk with exactly the same name as that stored
+in the archive. In the majority of cases this is the desired behavior
+of a file archiver. However, there are some cases when it is not.
+
+First of all, it is often unsafe to extract archive members with
+absolute file names or those that begin with a @file{../}. @GNUTAR{}
+takes special precautions when extracting such names and provides a
+special option for handling them, which is described in
+@ref{absolute}.
+
+Secondly, you may wish to extract file names without some leading
+directory components, or with otherwise modified names. In other
+cases it is desirable to store files under differing names in the
+archive.
+
+@GNUTAR{} provides two options for these needs.
+
+@table @option
+@opindex strip-components
+@item --strip-components=@var{number}
+Strip given @var{number} of leading components from file names before
+extraction.
+@end table
+
+For example, suppose you have archived whole @file{/usr} hierarchy to
+a tar archive named @file{usr.tar}. Among other files, this archive
+contains @file{usr/include/stdlib.h}, which you wish to extract to
+the current working directory. To do so, you type:
+
+@smallexample
+$ @kbd{tar -xf usr.tar --strip=2 usr/include/stdlib.h}
+@end smallexample
+
+The option @option{--strip=2} instructs @command{tar} to strip the
+two leading components (@file{usr/} and @file{include/}) off the file
+name.
+
+If you add to the above invocation @option{--verbose} (@option{-v})
+option, you will note that the verbose listing still contains the
+full file name, with the two removed components still in place. This
+can be inconvenient, so @command{tar} provides a special option for
+altering this behavior:
+
+@anchor{show-transformed-names}
+@table @option
+@opindex --show-transformed-names
+@item --show-transformed-names
+Display file or member names with all requested transformations
+applied.
+@end table
+
+@noindent
+For example:
+
+@smallexample
+@group
+$ @kbd{tar -xf usr.tar -v --strip=2 usr/include/stdlib.h}
+usr/include/stdlib.h
+$ @kbd{tar -xf usr.tar -v --strip=2 --show-transformed usr/include/stdlib.h}
+stdlib.h
+@end group
+@end smallexample
+
+Notice that in both cases the file is @file{stdlib.h} extracted to the
+current working directory, @option{--show-transformed-names} affects
+only the way its name is displayed.
+
+This option is especially useful for verifying whether the invocation
+will have the desired effect. Thus, before running
+
+@smallexample
+$ @kbd{tar -x --strip=@var{n}}
+@end smallexample
+
+@noindent
+it is often advisable to run
+
+@smallexample
+$ @kbd{tar -t -v --show-transformed --strip=@var{n}}
+@end smallexample
+
+@noindent
+to make sure the command will produce the intended results.
+
+In case you need to apply more complex modifications to the file name,
+@GNUTAR{} provides a general-purpose transformation option:
+
+@table @option
+@opindex --transform
+@item --transform=@var{expression}
+Modify file names using supplied @var{expression}.
+@end table
+
+@noindent
+The @var{expression} is a @command{sed}-like replace expression of the
+form:
+
+@smallexample
+s/@var{regexp}/@var{replace}/[@var{flags}]
+@end smallexample
+
+@noindent
+where @var{regexp} is a @dfn{regular expression}, @var{replace} is a
+replacement for each file name part that matches @var{regexp}. Both
+@var{regexp} and @var{replace} are described in detail in
+@ref{The "s" Command, The "s" Command, The `s' Command, sed, GNU sed}.
+
+Supported @var{flags} are:
+
+@table @samp
+@item g
+Apply the replacement to @emph{all} matches to the @var{regexp}, not
+just the first.
+
+@item i
+Use case-insensitive matching
+
+@item x
+@var{regexp} is an @dfn{extended regular expression} (@pxref{Extended
+regexps, Extended regular expressions, Extended regular expressions,
+sed, GNU sed}).
+
+@item @var{number}
+Only replace the @var{number}th match of the @var{regexp}.
+
+Note: the @var{posix} standard does not specify what should happen
+when you mix the @samp{g} and @var{number} modifiers. @GNUTAR{}
+follows the GNU @command{sed} implementation in this regard, so
+the the interaction is defined to be: ignore matches before the
+@var{number}th, and then match and replace all matches from the
+@var{number}th on.
+
+@end table
+
+Any delimiter can be used in lieue of @samp{/}, the only requirement being
+that it be used consistently throughout the expression. For example,
+the following two expressions are equivalent:
+
+@smallexample
+@group
+s/one/two/
+s,one,two,
+@end group
+@end smallexample
+
+Changing delimiters is often useful when the @var{regex} contains
+slashes. For example, it is more convenient to write @code{s,/,-,} than
+@code{s/\//-/}.
+
+Here are several examples of @option{--transform} usage:
+
+@enumerate
+@item Extract @file{usr/} hierarchy into @file{usr/local/}:
+
+@smallexample
+$ @kbd{tar --transform='s,usr/,usr/local/,' -x -f arch.tar}
+@end smallexample
+
+@item Strip two leading directory components (equivalent to
+@option{--strip-components=2}):
+
+@smallexample
+$ @kbd{tar --transform='s,/*[^/]*/[^/]*/,,' -x -f arch.tar}
+@end smallexample
+
+@item Prepend @file{/prefix/} to each file name:
+
+@smallexample
+$ @kbd{tar --transform 's,^,/prefix/,' -x -f arch.tar}
+@end smallexample
+
+@item Convert each file name to lower case:
+
+@smallexample
+$ @kbd{tar --transform 's/.*/\L&/' -x -f arch.tar}
+@end smallexample
+
+@end enumerate
+
+Unlike @option{--strip-components}, @option{--transform} can be used
+in any @GNUTAR{} operation mode. For example, the following command
+adds files to the archive while replacing the leading @file{usr/}
+component with @file{var/}:
+
+@smallexample
+$ @kbd{tar -cf arch.tar --transform='s,^usr/,var/,' /}
+@end smallexample
+
+To test @option{--transform} effect we suggest using
+@option{--show-transformed-names} option:
+
+@smallexample
+$ @kbd{tar -cf arch.tar --transform='s,^usr/,var/,' \
+ --verbose --show-transformed-names /}
+@end smallexample
+
+If both @option{--strip-components} and @option{--transform} are used
+together, then @option{--transform} is applied first, and the required
+number of components is then stripped from its result.
+
@node after
@section Operating Only on New Files
@UNREVISED
* Portability:: Making @command{tar} Archives More Portable
* Compression:: Using Less Space through Compression
* Attributes:: Handling File Attributes
-* Standard:: The Standard Format
-* Extensions:: @acronym{GNU} Extensions to the Archive Format
* cpio:: Comparison of @command{tar} and @command{cpio}
@end menu
@cindex POSIX archive format
@cindex PAX archive format
-The version @value{VERSION} of @GNUTAR{} is able
-to read and create archives conforming to @acronym{POSIX.1-2001} standard.
+Starting from version 1.14 @GNUTAR{} features full support for
+@acronym{POSIX.1-2001} archives.
A @acronym{POSIX} conformant archive will be created if @command{tar}
-was given @option{--format=posix} option.
+was given @option{--format=posix} (@option{--format=pax}) option. No
+special option is required to read and extract from a @acronym{POSIX}
+archive.
+
+@menu
+* PAX keywords:: Controlling Extended Header Keywords.
+@end menu
+
+@node PAX keywords
+@subsubsection Controlling Extended Header Keywords
+
+@table @option
+@opindex pax-option
+@item --pax-option=@var{keyword-list}
+Handle keywords in @acronym{PAX} extended headers. This option is
+equivalent to @option{-o} option of the @command{pax} utility.
+@end table
+
+@var{Keyword-list} is a comma-separated
+list of keyword options, each keyword option taking one of
+the following forms:
+
+@table @code
+@item delete=@var{pattern}
+When used with one of archive-creation commands,
+this option instructs @command{tar} to omit from extended header records
+that it produces any keywords matching the string @var{pattern}.
+
+When used in extract or list mode, this option instructs tar
+to ignore any keywords matching the given @var{pattern} in the extended
+header records. In both cases, matching is performed using the pattern
+matching notation described in @acronym{POSIX 1003.2}, 3.13
+(@pxref{wildcards}). For example:
+
+@smallexample
+--pax-option delete=security.*
+@end smallexample
+
+would suppress security-related information.
+
+@item exthdr.name=@var{string}
+
+This keyword allows user control over the name that is written into the
+ustar header blocks for the extended headers. The name is obtained
+from @var{string} after making the following substitutions:
+
+@multitable @columnfractions .25 .55
+@headitem Meta-character @tab Replaced By
+@item %d @tab The directory name of the file, equivalent to the
+result of the @command{dirname} utility on the translated pathname.
+@item %f @tab The filename of the file, equivalent to the result
+of the @command{basename} utility on the translated pathname.
+@item %p @tab The process ID of the @command{tar} process.
+@item %% @tab A @samp{%} character.
+@end multitable
+
+Any other @samp{%} characters in @var{string} produce undefined
+results.
+
+If no option @samp{exthdr.name=string} is specified, @command{tar}
+will use the following default value:
+
+@smallexample
+%d/PaxHeaders.%p/%f
+@end smallexample
+
+@item globexthdr.name=@var{string}
+This keyword allows user control over the name that is written into
+the ustar header blocks for global extended header records. The name
+is obtained from the contents of @var{string}, after making
+the following substitutions:
+
+@multitable @columnfractions .25 .55
+@headitem Meta-character @tab Replaced By
+@item %n @tab An integer that represents the
+sequence number of the global extended header record in the archive,
+starting at 1.
+@item %p @tab The process ID of the @command{tar} process.
+@item %% @tab A @samp{%} character.
+@end multitable
+
+Any other @samp{%} characters in @var{string} produce undefined results.
+
+If no option @samp{globexthdr.name=string} is specified, @command{tar}
+will use the following default value:
+
+@smallexample
+$TMPDIR/GlobalHead.%p.%n
+@end smallexample
+
+@noindent
+where @samp{$TMPDIR} represents the value of the @var{TMPDIR}
+environment variable. If @var{TMPDIR} is not set, @command{tar}
+uses @samp{/tmp}.
+
+@item @var{keyword}=@var{value}
+When used with one of archive-creation commands, these keyword/value pairs
+will be included at the beginning of the archive in a global extended
+header record. When used with one of archive-reading commands,
+@command{tar} will behave as if it has encountered these keyword/value
+pairs at the beginning of the archive in a global extended header
+record.
+
+@item @var{keyword}:=@var{value}
+When used with one of archive-creation commands, these keyword/value pairs
+will be included as records at the beginning of an extended header for
+each file. This is effectively equivalent to @var{keyword}=@var{value}
+form except that it creates no global extended header records.
+
+When used with one of archive-reading commands, @command{tar} will
+behave as if these keyword/value pairs were included as records at the
+end of each extended header; thus, they will override any global or
+file-specific extended header record keywords of the same names.
+For example, in the command:
+
+@smallexample
+tar --format=posix --create \
+ --file archive --pax-option gname:=user .
+@end smallexample
+
+the group name will be forced to a new value for all files
+stored in the archive.
+@end table
@node Checksumming
@subsection Checksumming Problems
implement your own filters, not necessarily dealing with
compression/decomression. For example, suppose you wish to implement
PGP encryption on top of compression, using @command{gpg} (@pxref{Top,
-gpg, gpg ---- encryption and signing tool, gpg}). The following
-script does that:
+gpg, gpg ---- encryption and signing tool, gpg, GNU Privacy Guard
+Manual}). The following script does that:
@smallexample
@group
@end table
-@node Standard
-@section Basic Tar Format
-@UNREVISED
-
-While an archive may contain many files, the archive itself is a
-single ordinary file. Like any other file, an archive file can be
-written to a storage device such as a tape or disk, sent through a
-pipe or over a network, saved on the active file system, or even
-stored in another archive. An archive file is not easy to read or
-manipulate without using the @command{tar} utility or Tar mode in
-@acronym{GNU} Emacs.
-
-Physically, an archive consists of a series of file entries terminated
-by an end-of-archive entry, which consists of two 512 blocks of zero
-bytes. A file
-entry usually describes one of the files in the archive (an
-@dfn{archive member}), and consists of a file header and the contents
-of the file. File headers contain file names and statistics, checksum
-information which @command{tar} uses to detect file corruption, and
-information about file types.
-
-Archives are permitted to have more than one member with the same
-member name. One way this situation can occur is if more than one
-version of a file has been stored in the archive. For information
-about adding new versions of a file to an archive, see @ref{update}.
-@FIXME-xref{To learn more about having more than one archive member with the
-same name, see -backup node, when it's written.}
-
-In addition to entries describing archive members, an archive may
-contain entries which @command{tar} itself uses to store information.
-@xref{label}, for an example of such an archive entry.
-
-A @command{tar} archive file contains a series of blocks. Each block
-contains @code{BLOCKSIZE} bytes. Although this format may be thought
-of as being on magnetic tape, other media are often used.
-
-Each file archived is represented by a header block which describes
-the file, followed by zero or more blocks which give the contents
-of the file. At the end of the archive file there are two 512-byte blocks
-filled with binary zeros as an end-of-file marker. A reasonable system
-should write such end-of-file marker at the end of an archive, but
-must not assume that such a block exists when reading an archive. In
-particular @GNUTAR{} always issues a warning if it does not encounter it.
-
-The blocks may be @dfn{blocked} for physical I/O operations.
-Each record of @var{n} blocks (where @var{n} is set by the
-@option{--blocking-factor=@var{512-size}} (@option{-b @var{512-size}}) option to @command{tar}) is written with a single
-@w{@samp{write ()}} operation. On magnetic tapes, the result of
-such a write is a single record. When writing an archive,
-the last record of blocks should be written at the full size, with
-blocks after the zero block containing all zeros. When reading
-an archive, a reasonable system should properly handle an archive
-whose last record is shorter than the rest, or which contains garbage
-records after a zero block.
-
-The header block is defined in C as follows. In the @GNUTAR{}
-distribution, this is part of file @file{src/tar.h}:
-
-@smallexample
-@include header.texi
-@end smallexample
-
-All characters in header blocks are represented by using 8-bit
-characters in the local variant of ASCII. Each field within the
-structure is contiguous; that is, there is no padding used within
-the structure. Each character on the archive medium is stored
-contiguously.
-
-Bytes representing the contents of files (after the header block
-of each file) are not translated in any way and are not constrained
-to represent characters in any character set. The @command{tar} format
-does not distinguish text files from binary files, and no translation
-of file contents is performed.
-
-The @code{name}, @code{linkname}, @code{magic}, @code{uname}, and
-@code{gname} are null-terminated character strings. All other fields
-are zero-filled octal numbers in ASCII. Each numeric field of width
-@var{w} contains @var{w} minus 1 digits, and a null.
-
-The @code{name} field is the file name of the file, with directory names
-(if any) preceding the file name, separated by slashes.
-
-@FIXME{how big a name before field overflows?}
-
-The @code{mode} field provides nine bits specifying file permissions
-and three bits to specify the Set UID, Set GID, and Save Text
-(@dfn{sticky}) modes. Values for these bits are defined above.
-When special permissions are required to create a file with a given
-mode, and the user restoring files from the archive does not hold such
-permissions, the mode bit(s) specifying those special permissions
-are ignored. Modes which are not supported by the operating system
-restoring files from the archive will be ignored. Unsupported modes
-should be faked up when creating or updating an archive; e.g., the
-group permission could be copied from the @emph{other} permission.
-
-The @code{uid} and @code{gid} fields are the numeric user and group
-ID of the file owners, respectively. If the operating system does
-not support numeric user or group IDs, these fields should be ignored.
-
-The @code{size} field is the size of the file in bytes; linked files
-are archived with this field specified as zero. @FIXME-xref{Modifiers, in
-particular the @option{--incremental} (@option{-G}) option.}
-
-The @code{mtime} field is the data modification time of the file at
-the time it was archived. It is the ASCII representation of the octal
-value of the last time the file's contents were modified, represented
-as an integer number of
-seconds since January 1, 1970, 00:00 Coordinated Universal Time.
-
-The @code{chksum} field is the ASCII representation of the octal value
-of the simple sum of all bytes in the header block. Each 8-bit
-byte in the header is added to an unsigned integer, initialized to
-zero, the precision of which shall be no less than seventeen bits.
-When calculating the checksum, the @code{chksum} field is treated as
-if it were all blanks.
-
-The @code{typeflag} field specifies the type of file archived. If a
-particular implementation does not recognize or permit the specified
-type, the file will be extracted as if it were a regular file. As this
-action occurs, @command{tar} issues a warning to the standard error.
-
-The @code{atime} and @code{ctime} fields are used in making incremental
-backups; they store, respectively, the particular file's access and
-status change times.
-
-The @code{offset} is used by the @option{--multi-volume} (@option{-M}) option, when
-making a multi-volume archive. The offset is number of bytes into
-the file that we need to restart at to continue the file on the next
-tape, i.e., where we store the location that a continued file is
-continued at.
-
-The following fields were added to deal with sparse files. A file
-is @dfn{sparse} if it takes in unallocated blocks which end up being
-represented as zeros, i.e., no useful data. A test to see if a file
-is sparse is to look at the number blocks allocated for it versus the
-number of characters in the file; if there are fewer blocks allocated
-for the file than would normally be allocated for a file of that
-size, then the file is sparse. This is the method @command{tar} uses to
-detect a sparse file, and once such a file is detected, it is treated
-differently from non-sparse files.
-
-Sparse files are often @code{dbm} files, or other database-type files
-which have data at some points and emptiness in the greater part of
-the file. Such files can appear to be very large when an @samp{ls
--l} is done on them, when in truth, there may be a very small amount
-of important data contained in the file. It is thus undesirable
-to have @command{tar} think that it must back up this entire file, as
-great quantities of room are wasted on empty blocks, which can lead
-to running out of room on a tape far earlier than is necessary.
-Thus, sparse files are dealt with so that these empty blocks are
-not written to the tape. Instead, what is written to the tape is a
-description, of sorts, of the sparse file: where the holes are, how
-big the holes are, and how much data is found at the end of the hole.
-This way, the file takes up potentially far less room on the tape,
-and when the file is extracted later on, it will look exactly the way
-it looked beforehand. The following is a description of the fields
-used to handle a sparse file:
-
-The @code{sp} is an array of @code{struct sparse}. Each @code{struct
-sparse} contains two 12-character strings which represent an offset
-into the file and a number of bytes to be written at that offset.
-The offset is absolute, and not relative to the offset in preceding
-array element.
-
-The header can hold four of these @code{struct sparse} at the moment;
-if more are needed, they are not stored in the header.
-
-The @code{isextended} flag is set when an @code{extended_header}
-is needed to deal with a file. Note that this means that this flag
-can only be set when dealing with a sparse file, and it is only set
-in the event that the description of the file will not fit in the
-allotted room for sparse structures in the header. In other words,
-an extended_header is needed.
-
-The @code{extended_header} structure is used for sparse files which
-need more sparse structures than can fit in the header. The header can
-fit 4 such structures; if more are needed, the flag @code{isextended}
-gets set and the next block is an @code{extended_header}.
-
-Each @code{extended_header} structure contains an array of 21
-sparse structures, along with a similar @code{isextended} flag
-that the header had. There can be an indeterminate number of such
-@code{extended_header}s to describe a sparse file.
-
-@table @asis
-
-@item @code{REGTYPE}
-@itemx @code{AREGTYPE}
-These flags represent a regular file. In order to be compatible
-with older versions of @command{tar}, a @code{typeflag} value of
-@code{AREGTYPE} should be silently recognized as a regular file.
-New archives should be created using @code{REGTYPE}. Also, for
-backward compatibility, @command{tar} treats a regular file whose name
-ends with a slash as a directory.
-
-@item @code{LNKTYPE}
-This flag represents a file linked to another file, of any type,
-previously archived. Such files are identified in Unix by each
-file having the same device and inode number. The linked-to name is
-specified in the @code{linkname} field with a trailing null.
-
-@item @code{SYMTYPE}
-This represents a symbolic link to another file. The linked-to name
-is specified in the @code{linkname} field with a trailing null.
-
-@item @code{CHRTYPE}
-@itemx @code{BLKTYPE}
-These represent character special files and block special files
-respectively. In this case the @code{devmajor} and @code{devminor}
-fields will contain the major and minor device numbers respectively.
-Operating systems may map the device specifications to their own
-local specification, or may ignore the entry.
-
-@item @code{DIRTYPE}
-This flag specifies a directory or sub-directory. The directory
-name in the @code{name} field should end with a slash. On systems where
-disk allocation is performed on a directory basis, the @code{size} field
-will contain the maximum number of bytes (which may be rounded to
-the nearest disk block allocation unit) which the directory may
-hold. A @code{size} field of zero indicates no such limiting. Systems
-which do not support limiting in this manner should ignore the
-@code{size} field.
-
-@item @code{FIFOTYPE}
-This specifies a FIFO special file. Note that the archiving of a
-FIFO file archives the existence of this file and not its contents.
-
-@item @code{CONTTYPE}
-This specifies a contiguous file, which is the same as a normal
-file except that, in operating systems which support it, all its
-space is allocated contiguously on the disk. Operating systems
-which do not allow contiguous allocation should silently treat this
-type as a normal file.
-
-@item @code{A} @dots{} @code{Z}
-These are reserved for custom implementations. Some of these are
-used in the @acronym{GNU} modified format, as described below.
-
-@end table
-
-Other values are reserved for specification in future revisions of
-the P1003 standard, and should not be used by any @command{tar} program.
-
-The @code{magic} field indicates that this archive was output in
-the P1003 archive format. If this field contains @code{TMAGIC},
-the @code{uname} and @code{gname} fields will contain the ASCII
-representation of the owner and group of the file respectively.
-If found, the user and group IDs are used rather than the values in
-the @code{uid} and @code{gid} fields.
-
-For references, see ISO/IEC 9945-1:1990 or IEEE Std 1003.1-1990, pages
-169-173 (section 10.1) for @cite{Archive/Interchange File Format}; and
-IEEE Std 1003.2-1992, pages 380-388 (section 4.48) and pages 936-940
-(section E.4.48) for @cite{pax - Portable archive interchange}.
-
-@node Extensions
-@section @acronym{GNU} Extensions to the Archive Format
-@UNREVISED
-
-The @acronym{GNU} format uses additional file types to describe new types of
-files in an archive. These are listed below.
-
-@table @code
-@item GNUTYPE_DUMPDIR
-@itemx 'D'
-This represents a directory and a list of files created by the
-@option{--incremental} (@option{-G}) option. The @code{size} field gives the total
-size of the associated list of files. Each file name is preceded by
-either a @samp{Y} (the file should be in this archive) or an @samp{N}.
-(The file is a directory, or is not stored in the archive.) Each file
-name is terminated by a null. There is an additional null after the
-last file name.
-
-@item GNUTYPE_MULTIVOL
-@itemx 'M'
-This represents a file continued from another volume of a multi-volume
-archive created with the @option{--multi-volume} (@option{-M}) option. The original
-type of the file is not given here. The @code{size} field gives the
-maximum size of this piece of the file (assuming the volume does
-not end before the file is written out). The @code{offset} field
-gives the offset from the beginning of the file where this part of
-the file begins. Thus @code{size} plus @code{offset} should equal
-the original size of the file.
-
-@item GNUTYPE_SPARSE
-@itemx 'S'
-This flag indicates that we are dealing with a sparse file. Note
-that archiving a sparse file requires special operations to find
-holes in the file, which mark the positions of these holes, along
-with the number of bytes of data to be found after the hole.
-
-@item GNUTYPE_VOLHDR
-@itemx 'V'
-This file type is used to mark the volume header that was given with
-the @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) option when the archive was created. The @code{name}
-field contains the @code{name} given after the @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) option.
-The @code{size} field is zero. Only the first file in each volume
-of an archive should have this type.
-
-@end table
-
-You may have trouble reading a @acronym{GNU} format archive on a
-non-@acronym{GNU} system if the options @option{--incremental} (@option{-G}),
-@option{--multi-volume} (@option{-M}), @option{--sparse} (@option{-S}), or @option{--label=@var{archive-label}} (@option{-V @var{archive-label}}) were
-used when writing the archive. In general, if @command{tar} does not
-use the @acronym{GNU}-added fields of the header, other versions of
-@command{tar} should be able to read the archive. Otherwise, the
-@command{tar} program will give an error, the most likely one being a
-checksum error.
-
@node cpio
@section Comparison of @command{tar} and @command{cpio}
@UNREVISED
@FIXME{Is there a better way to frob the spacing on the list?}
If you don't specify a @var{tapename}, @command{mt} uses the environment
-variable @env{TAPE}; if @env{TAPE} is not set, @command{mt} uses the device
-@file{/dev/rmt12}.
+variable @env{TAPE}; if @env{TAPE} is not set, @command{mt} will use
+the default device specified in your @file{sys/mtio.h} file
+(@code{DEFTAPE} variable). If this is not defined, the program will
+display a descriptive error message and exit with code 1.
@command{mt} returns a 0 exit status when the operation(s) were
successful, 1 if the command was unrecognized, and 2 if an operation
@vrindex TAR_SUBCOMMAND, info script environment variable
@item TAR_SUBCOMMAND
-Short option describing the operation @command{tar} is executed.
+Short option describing the operation @command{tar} is executing
@xref{Operations}, for a complete list of subcommand options.
@vrindex TAR_FORMAT, info script environment variable
If you want to tar to mimic the behavior of versions prior to 1.15.91,
add this option to your @env{TAR_OPTIONS} variable.
-@xref{Wildcards}, for the detailed discussion of the use of globbing
+@xref{wildcards}, for the detailed discussion of the use of globbing
patterns by @GNUTAR{}.
@item Use of short option @option{-o}.
distribution tarballs. @xref{Formats,v7}, for the detailed discussion
of this issue and its implications.
-@FIXME{Change the first argument to tar-formats if and when Automake
-people accept my patch to the documentation, and the new Automake is
-out --Sergey 2006-05-25}.
+@FIXME{Change the first argument to tar-formats when the new Automake is
+out. The proposition to add @anchor{} to the appropriate place of its
+docs was accepted by Automake people --Sergey 2006-05-25}.
@xref{Options, tar-v7, Changing Automake's Behavior,
automake, GNU Automake}, for a description on how to use various
archive formats with @command{automake}.
@appendix Genfile
@include genfile.texi
-@node Snapshot Files
-@appendix Format of the Incremental Snapshot Files
-@include snapshot.texi
+@node Tar Internals
+@appendix Tar Internals
+@include intern.texi
@node Free Software Needs Free Documentation
@appendix Free Software Needs Free Documentation
projects / chaz / tar / blobdiff