@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
* 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
* 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
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.
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
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.
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
projects / chaz / tar / blobdiff