@include value.texi
@defcodeindex op
+@defcodeindex kw
@c Put everything in one index (arbitrarily chosen to be the concept index).
@syncodeindex fn cp
@syncodeindex ky cp
@syncodeindex pg cp
@syncodeindex vr cp
+@syncodeindex kw cp
@copying
from archives.
Copyright @copyright{} 1992, 1994, 1995, 1996, 1997, 1999, 2000, 2001,
-2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+2003, 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
* defaults::
* verbose::
* checkpoints::
+* warnings::
* interactive::
The Three Option Styles
@smallexample
@group
-$ @kbd{tar cfv archive /etc/mail}
+$ @kbd{tar --create --verbose --file archive /etc/mail}
tar: Removing leading `/' from member names
/etc/mail/
/etc/mail/sendmail.cf
/etc/mail/aliases
-$ @kbd{tar tf archive}
+$ @kbd{tar --test --file archive}
etc/mail/
etc/mail/sendmail.cf
etc/mail/aliases
@node extract
@section How to Extract Members from an Archive
-@UNREVISED
@cindex Extraction
@cindex Retrieving files from an archive
@cindex Resurrecting files from an archive
@node tar invocation
@chapter Invoking @GNUTAR{}
-@UNREVISED
This chapter is about how one invokes the @GNUTAR{}
command, from the command synopsis (@pxref{Synopsis}). There are
* defaults::
* verbose::
* checkpoints::
+* warnings::
* interactive::
@end menu
@cindex return status
Besides successful exits, @GNUTAR{} may fail for
many reasons. Some reasons correspond to bad usage, that is, when the
-@command{tar} command is improperly written. Errors may be
-encountered later, while encountering an error processing the archive
-or the files. Some errors are recoverable, in which case the failure
-is delayed until @command{tar} has completed all its work. Some
-errors are such that it would not meaningful, or at least risky, to
-continue processing: @command{tar} then aborts processing immediately.
-All abnormal exits, whether immediate or delayed, should always be
-clearly diagnosed on @code{stderr}, after a line stating the nature of
-the error.
+@command{tar} command line is improperly written. Errors may be
+encountered later, while processing the archive or the files. Some
+errors are recoverable, in which case the failure is delayed until
+@command{tar} has completed all its work. Some errors are such that
+it would be not meaningful, or at least risky, to continue processing:
+@command{tar} then aborts processing immediately. All abnormal exits,
+whether immediate or delayed, should always be clearly diagnosed on
+@code{stderr}, after a line stating the nature of the error.
Possible exit codes of @GNUTAR{} are summarized in the following
table:
allow you to perform a variety of tasks. You are required to choose
one operating mode each time you employ the @command{tar} program by
specifying one, and only one operation as an argument to the
-@command{tar} command (two lists of four operations each may be found
+@command{tar} command (the corresponding options may be found
at @ref{frequent operations} and @ref{Operations}). Depending on
circumstances, you may also wish to customize how the chosen operating
mode behaves. For example, you may wish to change the way the output
@node Long Options
@subsection Long Option Style
+@cindex long options
+@cindex options, long style
+@cindex options, GNU style
+@cindex options, mnemonic names
Each option has at least one @dfn{long} (or @dfn{mnemonic}) name starting with two
dashes in a row, e.g., @option{--list}. The long names are more clear than
their corresponding short or old names. It sometimes happens that a
gives a fairly good set of hints about what the command does, even
for those not fully acquainted with @command{tar}.
+@cindex arguments to long options
+@cindex long options with mandatory arguments
Long options which require arguments take those arguments
immediately following the option name. There are two ways of
specifying a mandatory argument. It can be separated from the
@file{archive.tar} as argument by using any of the following notations:
@option{--file=archive.tar} or @option{--file archive.tar}.
+@cindex optional arguments to long options
+@cindex long options with optional arguments
In contrast, optional arguments must always be introduced using
an equal sign. For example, the @option{--backup} option takes
an optional argument specifying backup type. It must be used
@node Short Options
@subsection Short Option Style
+@cindex short options
+@cindex options, short style
+@cindex options, traditional
Most options also have a @dfn{short option} name. Short options start with
a single dash, and are followed by a single character, e.g., @option{-t}
(which is equivalent to @option{--list}). The forms are absolutely
The short option names are faster to type than long option names.
+@cindex arguments to short options
+@cindex short options with mandatory arguments
Short options which require arguments take their arguments immediately
following the option, usually separated by white space. It is also
possible to stick the argument right after the short option name, using
@w{@option{-f @var{archive-name}}} denote the option which indicates a
specific archive, here named @file{archive.tar}.
+@cindex optional arguments to short options
+@cindex short options with optional arguments
Short options which take optional arguments take their arguments
immediately following the option letter, @emph{without any intervening
white space characters}.
@node Old Options
@subsection Old Option Style
-@UNREVISED
+@cindex options, old style
+@cindex old option style
Like short options, @dfn{old options} are single letters. However, old options
must be written together as a single clumped set, without spaces separating
long option @option{--list}. So for example, the command @w{@samp{tar
cv}} specifies the option @option{-v} in addition to the operation @option{-c}.
+@cindex arguments to old options
+@cindex old options with mandatory arguments
When options that need arguments are given together with the command,
all the associated arguments follow, in the same order as the options.
Thus, the example given previously could also be written in the old
@node Mixing
@subsection Mixing Option Styles
+@cindex options, mixing different styles
All three styles may be intermixed in a single @command{tar} command,
so long as the rules for each style are fully
respected@footnote{Before @GNUTAR{} version 1.11.6,
want a visual indication that @command{tar} is still running, but
don't want to see @option{--verbose} output. You can also instruct
@command{tar} to execute a list of actions on each checkpoint, see
-@option{--checklist-action} below. For a detailed description, see
+@option{--checkpoint-action} below. For a detailed description, see
@ref{checkpoints}.
@opsummary{checkpoint-action}
@command{tar} will only operate on archives that have a label matching
the pattern specified in @var{name}. @xref{Tape Files}.
+@opsummary{level}
+@item --level=@var{n}
+Force incremental backup of level @var{n}. As of @GNUTAR version
+@value{VERSION}, the option @option{--level=0} truncates the snapshot
+file, thereby forcing the level 0 dump. Other values of @var{n} are
+effectively ignored. @xref{--level=0}, for details and examples.
+
+The use of this option is valid only in conjunction with the
+@option{--listed-incremental} option. @xref{Incremental Dumps},
+for a detailed description.
+
@opsummary{listed-incremental}
@item --listed-incremental=@var{snapshot-file}
@itemx -g @var{snapshot-file}
@opsummary{lzma}
@item --lzma
-@itemx -J
This option tells @command{tar} to read or write archives through
@command{lzma}. @xref{gzip}.
the permissions specified in the archive. This is the default behavior
for ordinary users.
+@opsummary{no-seek}
+@item --no-seek
+
+The archive media does not support seeks to arbitrary
+locations. Usually @command{tar} determines automatically whether
+the archive can be seeked or not. Use this option to disable this
+mechanism.
+
@opsummary{no-unquote}
@item --no-unquote
Treat all input file or member names literally, do not interpret
Assume that the archive media supports seeks to arbitrary
locations. Usually @command{tar} determines automatically whether
the archive can be seeked or not. This option is intended for use
-in cases when such recognition fails.
+in cases when such recognition fails. It takes effect only if the
+archive is open for reading (e.g. with @option{--list} or
+@option{--extract} options).
@opsummary{show-defaults}
@item --show-defaults
@opsummary{use-compress-program}
@item --use-compress-program=@var{prog}
+@itemx -I=@var{prog}
Instructs @command{tar} to access the archive through @var{prog}, which is
presumed to be a compression program of some sort. @xref{gzip}.
keep track of which volume of a multi-volume archive it is working in
@var{file}. @xref{volno-file}.
+@opsummary{warning}
+@item --warning=@var{keyword}
+
+Enable or disable warning messages identified by @var{keyword}. The
+messages are suppressed if @var{keyword} is prefixed with @samp{no-}.
+@xref{warnings}.
+
@opsummary{wildcards}
@item --wildcards
Use wildcards when matching member names with patterns.
@item --wildcards-match-slash
Wildcards match @samp{/}.
@xref{controlling pattern-matching}.
+
+@opsummary{xz}
+@item --xz
+@itemx -J
+Use @command{xz} for compressing or decompressing the archives. @xref{gzip}.
+
@end table
@node Short Option Summary
@item -G @tab @ref{--incremental}.
-@item -J @tab @ref{--lzma}.
+@item -J @tab @ref{--xz}.
@item -K @tab @ref{--starting-file}.
every message it would normally produce, the block number within the
archive where the message was triggered. Also, supplementary messages
are triggered when reading blocks full of NULs, or when hitting end of
-file on the archive. As of now, if the archive if properly terminated
+file on the archive. As of now, if the archive is properly terminated
with a NUL block, the reading of the file may stop before end of file
is met, so the position of end of file will not usually show when
@option{--block-number} (@option{-R}) is used. Note that @GNUTAR{}
@option{--checkpoint}. In this case, the default checkpoint frequency
(at each 10th record) is assumed.
+@node warnings
+@section Controlling Warning Messages
+
+Sometimes, while performing the requested task, @GNUTAR{} notices
+some conditions that are not exactly erros, but which the user
+should be aware of. When this happens, @command{tar} issues a
+@dfn{warning message} describing the condition. Warning messages
+are output to the standard error and they do not affect the exit
+code of @command{tar} command.
+
+@xopindex{warning, explained}
+@GNUTAR{} allows the user to suppress some or all of its warning
+messages:
+
+@table @option
+@item --warning=@var{keyword}
+Control display of the warning messages identified by @var{keyword}.
+If @var{keyword} starts with the prefix @samp{no-}, such messages are
+suppressed. Otherwise, they are enabled.
+
+Multiple @option{--warning} messages accumulate.
+
+The tables below list allowed values for @var{keyword} along with the
+warning messages they control.
+@end table
+
+@subheading Keywords controlling @command{tar} operation
+@table @asis
+@kwindex all
+@item all
+Enable all warning messages. This is the default.
+@kwindex none
+@item none
+Disable all warning messages.
+@kwindex filename-with-nuls
+@cindex @samp{file name read contains nul character}, warning message
+@item filename-with-nuls
+@samp{%s: file name read contains nul character}
+@kwindex alone-zero-block
+@cindex @samp{A lone zero block at}, warning message
+@item alone-zero-block
+@samp{A lone zero block at %s}
+@end table
+
+@subheading Keywords applicable for @command{tar --create}
+@table @asis
+@kwindex cachedir
+@cindex @samp{contains a cache directory tag}, warning message
+@item cachedir
+@samp{%s: contains a cache directory tag %s; %s}
+@kwindex file-shrank
+@cindex @samp{File shrank by %s bytes}, warning message
+@item file-shrank
+@samp{%s: File shrank by %s bytes; padding with zeros}
+@kwindex xdev
+@cindex @samp{file is on a different filesystem}, warning message
+@item xdev
+@samp{%s: file is on a different filesystem; not dumped}
+@kwindex file-ignored
+@cindex @samp{Unknown file type; file ignored}, warning message
+@cindex @samp{socket ignored}, warning message
+@cindex @samp{door ignored}, warning message
+@item file-ignored
+@samp{%s: Unknown file type; file ignored}
+@samp{%s: socket ignored}
+@*@samp{%s: door ignored}
+@kwindex file-unchanged
+@cindex @samp{file is unchanged; not dumped}, warning message
+@item file-unchanged
+@samp{%s: file is unchanged; not dumped}
+@kwindex ignore-archive
+@cindex @samp{file is the archive; not dumped}, warning message
+@kwindex ignore-archive
+@cindex @samp{file is the archive; not dumped}, warning message
+@item ignore-archive
+@samp{%s: file is the archive; not dumped}
+@kwindex file-removed
+@cindex @samp{File removed before we read it}, warning message
+@item file-removed
+@samp{%s: File removed before we read it}
+@kwindex file-changed
+@cindex @samp{file changed as we read it}, warning message
+@item file-changed
+@samp{%s: file changed as we read it}
+@end table
+
+@subheading Keywords applicable for @command{tar --extract}
+@table @asis
+@kwindex timestamp
+@cindex @samp{implausibly old time stamp %s}, warning message
+@cindex @samp{time stamp %s is %s s in the future}, warning message
+@item timestamp
+@samp{%s: implausibly old time stamp %s}
+@*@samp{%s: time stamp %s is %s s in the future}
+@kwindex contiguous-cast
+@cindex @samp{Extracting contiguous files as regular files}, warning message
+@item contiguous-cast
+@samp{Extracting contiguous files as regular files}
+@kwindex symlink-cast
+@cindex @samp{Attempting extraction of symbolic links as hard links}, warning message
+@item symlink-cast
+@samp{Attempting extraction of symbolic links as hard links}
+@kwindex unknown-cast
+@cindex @samp{Unknown file type `%c', extracted as normal file}, warning message
+@item unknown-cast
+@samp{%s: Unknown file type `%c', extracted as normal file}
+@kwindex ignore-newer
+@cindex @samp{Current %s is newer or same age}, warning message
+@item ignore-newer
+@samp{Current %s is newer or same age}
+@kwindex unknown-keyword
+@cindex @samp{Ignoring unknown extended header keyword `%s'}, warning message
+@item unknown-keyword
+@samp{Ignoring unknown extended header keyword `%s'}
+@end table
+
+@subheading Keywords controlling incremental extraction:
+@table @asis
+@kwindex rename-directory
+@cindex @samp{%s: Directory has been renamed from %s}, warning message
+@cindex @samp{%s: Directory has been renamed}, warning message
+@item rename-directory
+@samp{%s: Directory has been renamed from %s}
+@*@samp{%s: Directory has been renamed}
+@kwindex new-directory
+@cindex @samp{%s: Directory is new}, warning message
+@item new-directory
+@samp{%s: Directory is new}
+@kwindex xdev
+@cindex @samp{%s: directory is on a different device: not purging}, warning message
+@item xdev
+@samp{%s: directory is on a different device: not purging}
+@kwindex bad-dumpdir
+@cindex @samp{Malformed dumpdir: 'X' never used}, warning message
+@item bad-dumpdir
+@samp{Malformed dumpdir: 'X' never used}
+@end table
+
@node interactive
@section Asking for Confirmation During Operations
@cindex Interactive operation
@node Operations
@subsection The Five Advanced @command{tar} Operations
-@UNREVISED
+@cindex basic operations
In the last chapter, you learned about the first three operations to
@command{tar}. This chapter presents the remaining five operations to
@command{tar}: @option{--append}, @option{--update}, @option{--concatenate},
@itemx -r
Add new entries to an archive that already exists.
@item --update
-@itemx -r
+@itemx -u
Add more recent copies of archive members to the end of an archive, if
they exist.
@item --concatenate
@node append
@subsection How to Add Files to Existing Archives: @option{--append}
-@UNREVISED
+@cindex appending files to existing archive
@opindex append
If you want to add files to an existing archive, you don't need to
create a new archive; you can use @option{--append} (@option{-r}).
member will end up being extracted, as it will replace the one
extracted before it, and so on.
+@cindex extracting @var{n}th copy of the file
+@xopindex{occurrence, described}
There exists a special option that allows you to get around this
behavior and extract (or list) only a particular copy of the file.
This is @option{--occurrence} option. If you run @command{tar} with
@cindex Members, replacing with other members
@cindex Replacing members with other members
+@xopindex{delete, using before --append}
If you want to replace an archive member, use @option{--delete} to
-delete the member you want to remove from the archive, , and then use
+delete the member you want to remove from the archive, and then use
@option{--append} to add the member you want to be in the archive. Note
that you can not change the order of the archive; the most recently
added member will still appear last. In this sense, you cannot truly
@node appending files
@subsubsection Appending Files to an Archive
-@UNREVISED
@cindex Adding files to an Archive
@cindex Appending files to an Archive
@cindex Archives, Appending files to
+@opindex append
The simplest way to add a file to an already existing archive is the
@option{--append} (@option{-r}) operation, which writes specified
@node multiple
@subsubsection Multiple Members with the Same Name
+@cindex members, multiple
+@cindex multiple members
You can use @option{--append} (@option{-r}) to add copies of files
which have been updated since the archive was created. (However, we
@node update
@subsection Updating an Archive
-@UNREVISED
@cindex Updating an archive
-
@opindex update
+
In the previous section, you learned how to use @option{--append} to
add a file to an existing archive. A related operation is
@option{--update} (@option{-u}). The @option{--update} operation
@node how to update
@subsubsection How to Update an Archive Using @option{--update}
+@opindex update
You must use file name arguments with the @option{--update}
(@option{-u}) operation. If you don't specify any files,
@node delete
@subsection Removing Archive Members Using @option{--delete}
-@UNREVISED
@cindex Deleting files from an archive
@cindex Removing files from an archive
@node compare
@subsection Comparing Archive Members with the File System
@cindex Verifying the currency of an archive
-@UNREVISED
@opindex compare
The @option{--compare} (@option{-d}), or @option{--diff} operation compares
@node extract options
@section Options Used by @option{--extract}
-@UNREVISED
+@cindex options for use with @option{--extract}
@xopindex{extract, additional options}
The previous chapter showed how to use @option{--extract} to extract
@node Reading
@subsection Options to Help Read Archives
@cindex Options when reading archives
-@UNREVISED
@cindex Reading incomplete records
@cindex Records, incomplete
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.)
+as having similar names through the side-effect of name truncation.
+@FIXME{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.
@node Backups
@chapter Performing Backups and Restoring Files
-@UNREVISED
+@cindex backups
-@GNUTAR{} 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
+@GNUTAR{} is distributed along with the scripts for performing backups
+and restores. 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:
-
-@smallexample
-http://www.cs.umd.edu/projects/amanda/amanda.html
-ftp://ftp.cs.umd.edu/pub/amanda
-@end smallexample
+This is free software, and it is available from @uref{http://www.amanda.org}.
@FIXME{
backups: @option{--listed-incremental=@var{snapshot-file}} (@option{-g
@var{snapshot-file}}) and @option{--incremental} (@option{-G}).
-@opindex listed-incremental
+@xopindex{listed-incremental, described}
The option @option{--listed-incremental} instructs tar to operate on
an incremental archive with additional metadata stored in a standalone
file, called a @dfn{snapshot file}. The purpose of this file is to help
/usr}
@end smallexample
+@anchor{--level=0}
+@xopindex{level, described}
+You can force @samp{level 0} backups either by removing the snapshot
+file before running @command{tar}, or by supplying the
+@option{--level=0} option, e.g.:
+
+@smallexample
+$ @kbd{tar --create \
+ --file=archive.2.tar \
+ --listed-incremental=/var/log/usr.snar-0 \
+ --level=0 \
+ /usr}
+@end smallexample
+
Incremental dumps depend crucially on time stamps, so the results are
unreliable if you modify a file's time stamps during dumping (e.g.,
with the @option{--atime-preserve=replace} option), or if you set the clock
@node Choosing
@chapter Choosing Files and Names for @command{tar}
-@UNREVISED
Certain options to @command{tar} enable you to specify a name for your
archive. Other options let you decide which files to include or exclude
@node file
@section Choosing and Naming Archive Files
-@UNREVISED
@cindex Naming an archive
@cindex Archive Name
@cindex Choosing an archive file
@cindex Where is the archive?
+@opindex file
By default, @command{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 @command{tar}
@cindex Reading file names from a file
@cindex Lists of file names
@cindex File Name arguments, alternatives
+@cindex @command{find}, using with @command{tar}
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
@option{--files-from=@var{file-of-names}} (@option{-T
@node exclude
@section Excluding Some Files
-@UNREVISED
@cindex File names, excluding files by
@cindex Excluding files by name and pattern
@cindex Excluding files by file system
+@opindex exclude
+@opindex exclude-from
To avoid operating on files whose names match a particular pattern,
use the @option{--exclude} or @option{--exclude-from} options.
@node after
@section Operating Only on New Files
-@UNREVISED
@cindex Excluding file by age
@cindex Data Modification time, excluding files by
modification of the file's data (rather than status
changes), then use the @option{--newer-mtime=@var{date}} option.
+@cindex --after-date and --update compared
+@cindex --newer-mtime and --update compared
You may use these options with any operation. Note that these options
differ from the @option{--update} (@option{-u}) operation in that they
allow you to specify a particular date against which @command{tar} can
@node recurse
@section Descending into Directories
-@UNREVISED
@cindex Avoiding recursion in directories
@cindex Descending directories, avoiding
@cindex Directories, avoiding recursion
@cindex Recursion in directories, avoiding
-@FIXME{arrggh! this is still somewhat confusing to me. :-< }
-
Usually, @command{tar} will recursively explore all directories (either
those given on the command line or through the @option{--files-from}
option) for the various files they contain. However, you may not always
want @command{tar} to act this way.
@opindex no-recursion
+@cindex @command{find}, using with @command{tar}
The @option{--no-recursion} option inhibits @command{tar}'s recursive descent
into specified directories. If you specify @option{--no-recursion}, you can
-use the @command{find} utility for hunting through levels of directories to
+use the @command{find} (@pxref{Top,, find, find, GNU Find Manual})
+utility for hunting through levels of directories to
construct a list of file names which you could then pass to @command{tar}.
@command{find} allows you to be more selective when choosing which files to
archive; see @ref{files}, for more information on using @command{find} with
-@command{tar}, or look.
+@command{tar}.
@table @option
@item --no-recursion
@node one
@section Crossing File System Boundaries
@cindex File system boundaries, not crossing
-@UNREVISED
@command{tar} will normally automatically cross file system boundaries in
order to archive files which are part of a directory tree. You can
@node absolute
@subsection Absolute File Names
-@UNREVISED
+@cindex absolute file names
+@cindex file names, absolute
+
+By default, @GNUTAR{} drops a leading @samp{/} on
+input or output, and complains about file names containing a @file{..}
+component. There is an option that turns off this behavior:
@table @option
@opindex absolute-names
containing a @file{..} file name component.
@end table
-By default, @GNUTAR{} drops a leading @samp{/} on
-input or output, and complains about file names containing a @file{..}
-component. This option turns off this behavior.
-
When @command{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
@FIXME{Should be an example in the tutorial/wizardry section using this
to transfer files between systems.}
-@FIXME{Is write access an issue?}
-
@table @option
@item --absolute-names
Preserves full file names (including superior directory names) when
@end table
-@FIXME{this is still horrible; need to talk with dan on monday.}
-
@command{tar} prints out a message about removing the @samp{/} from
file names. This message appears once per @GNUTAR{}
invocation. It represents something which ought to be told; ignoring
commands. The compression option is @option{-z} (@option{--gzip}) to
create a @command{gzip} compressed archive, @option{-j}
(@option{--bzip2}) to create a @command{bzip2} compressed archive,
-@option{-J} (@option{--lzma}) to create an @asis{LZMA} compressed
+@option{-J} (@option{--xz}) to create an @asis{XZ} archive,
+@option{--lzma} to create an @asis{LZMA} compressed
archive, @option{--lzop} to create an @asis{LSOP} archive, and
@option{-Z} (@option{--compress}) to use @command{compress} program.
For example:
@item @samp{.lzma} @tab @command{lzma}
@item @samp{.tlz} @tab @command{lzma}
@item @samp{.lzo} @tab @command{lzop}
+@item @samp{.xz} @tab @command{xz}
@end multitable
@opindex gzip
So, there are pros and cons. We'll see!
@opindex bzip2
+@item -J
+@itemx --xz
+Filter the archive through @code{xz}. Otherwise like
+@option{--gzip}.
+
@item -j
@itemx --bzip2
Filter the archive through @code{bzip2}. Otherwise like @option{--gzip}.
@opindex lzma
@item --lzma
-@itemx -J
Filter the archive through @command{lzma}. Otherwise like @option{--gzip}.
@opindex lzop
@opindex use-compress-program
@item --use-compress-program=@var{prog}
+@itemx -I=@var{prog}
Use external compression program @var{prog}. Use this option if you
have a compression program that @GNUTAR{} does not support. There
are two requirements to which @var{prog} should comply:
archive signed with your private key:
@smallexample
-$ @kbd{tar -cf foo.tar.gpgz --use-compress=gpgz .}
+$ @kbd{tar -cf foo.tar.gpgz -Igpgz .}
@end smallexample
@noindent
-Likewise, the following command will list its contents:
+Likewise, the command below will list its contents:
@smallexample
-$ @kbd{tar -tf foo.tar.gpgz --use-compress=gpgz .}
+$ @kbd{tar -tf foo.tar.gpgz -Igpgz .}
@end smallexample
@ignore
@node Attributes
@section Handling File Attributes
-@UNREVISED
+@cindex atrributes, files
+@cindex file attributes
When @command{tar} reads files, it updates their access times. To
avoid this, use the @option{--atime-preserve[=METHOD]} option, which can either
reset the access time retroactively or avoid changing it in the first
place.
-Handling of file attributes
-
@table @option
@opindex atime-preserve
@item --atime-preserve
@item --preserve
Same as both @option{--same-permissions} and @option{--same-order}.
-The @option{--preserve} option has no equivalent short option name.
-It is equivalent to @option{--same-permissions} plus @option{--same-order}.
-
-@FIXME{I do not see the purpose of such an option. (Neither I. FP.)
-Neither do I. --Sergey}
+This option is deprecated, and will be removed in @GNUTAR{} version 1.23.
@end table
@node hard links
@subsection Hard Links
-@UNREVISED{}
@cindex File names, using hard links
@cindex hard links, dereferencing
@cindex dereferencing hard links
use signed checksums, while @GNUTAR{} uses unsigned
checksums while creating archives, as per @acronym{POSIX} standards. On
reading, @GNUTAR{} computes both checksums and
-accept any. It is somewhat worrying that a lot of people may go
+accepts any. It is somewhat worrying that a lot of people may go
around doing backup of their files using faulty (or at least
non-standard) software, not learning about it until it's time to
restore their missing files with an incompatible file extractor, or
@cindex large values
@cindex future time stamps
@cindex negative time stamps
-@UNREVISED{}
+@UNREVISED
The above sections suggest to use @samp{oldest possible} archive
format if in doubt. However, sometimes it is not possible. If you
@node Blocking
@section Blocking
-@UNREVISED
+@cindex block
+@cindex record
@dfn{Block} and @dfn{record} terminology is rather confused, and it
is also confusing to the expert reader. On the other hand, readers
@end table
-@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} will use
the default device specified in your @file{sys/mtio.h} file
@node Tape Files
@subsection Tape Files
+@cindex labeling archives
+@opindex label
@UNREVISED
To give the archive a name which will be recorded in it, use the
distribution tarballs. @xref{Formats,v7}, for the detailed discussion
of this issue and its implications.
-@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,
+@xref{Options, tar-formats, Changing Automake's Behavior,
automake, GNU Automake}, for a description on how to use various
archive formats with @command{automake}.
projects / chaz / tar / blobdiff