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@@ -453,11 +453,8 @@ concepts of using a Unix-type operating system; @pxref{Tutorial}.)
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The third chapter presents the remaining five operations, and
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information about using @command{tar} options and option syntax.
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-@FIXME{this sounds more like a @acronym{GNU} Project Manuals Concept [tm] more
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-than the reality. should think about whether this makes sense to say
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-here, or not.} The other chapters are meant to be used as a
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-reference. Each chapter presents everything that needs to be said
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-about a specific topic.
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+The other chapters are meant to be used as a reference. Each chapter
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+presents everything that needs to be said about a specific topic.
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One of the chapters (@pxref{Date input formats}) exists in its
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entirety in other @acronym{GNU} manuals, and is mostly self-contained.
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@@ -687,7 +684,7 @@ change between directories; and how to figure out where you are in the
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file system. You should have some basic understanding of directory
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structure and how files are named according to which directory they are
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in. You should understand concepts such as standard output and standard
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-input, what various definitions of the term ``argument'' mean, and the
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+input, what various definitions of the term @samp{argument} mean, and the
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differences between relative and absolute file names. @FIXME{and what
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else?}
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@@ -752,10 +749,9 @@ You can write most of the @command{tar} operations and options in any
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of three forms: long (mnemonic) form, short form, and old style. Some
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of the operations and options have no short or ``old'' forms; however,
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the operations and options which we will cover in this tutorial have
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-corresponding abbreviations. @FIXME{make sure this is still the case,
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-at the end}We will indicate those abbreviations appropriately to get
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-you used to seeing them. (Note that the ``old style'' option forms
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-exist in @GNUTAR{} for compatibility with Unix
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+corresponding abbreviations. We will indicate those abbreviations
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+appropriately to get you used to seeing them. (Note that the ``old
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+style'' option forms exist in @GNUTAR{} for compatibility with Unix
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@command{tar}. In this book we present a full discussion of this way
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of writing options and operations (@pxref{Old Options}), and we discuss
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the other two styles of writing options (@xref{Long Options}, and
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@@ -2441,6 +2437,12 @@ record. @xref{Blocking Factor}.
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This option tells @command{tar} to read or write archives through
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@code{bzip2}. @xref{gzip}.
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+@opsummary{check-device}
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+@item --check-device
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+Check device numbers when creating a list of modified files for
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+incremental archiving. This is the default. @xref{device numbers},
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+for a detailed description.
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+
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@opsummary{checkpoint}
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@item --checkpoint[=@var{number}]
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@@ -2841,6 +2843,12 @@ changed). @xref{after}.
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An exclude pattern can match any subsequence of the name's components.
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@xref{controlling pattern-matching}.
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+@opsummary{no-check-device}
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+@item --no-check-device
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+Do not check device numbers when creating a list of modified files
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+for incremental archiving. @xref{device numbers}, for
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+a detailed description.
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+
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@opsummary{no-delay-directory-restore}
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@item --no-delay-directory-restore
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@@ -5677,21 +5685,40 @@ unreliable if you modify a file's time stamps during dumping (e.g.,
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with the @option{--atime-preserve=replace} option), or if you set the clock
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backwards.
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+@anchor{device numbers}
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@cindex Device numbers, using in incremental backups
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Metadata stored in snapshot files include device numbers, which,
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-obviously is supposed to be a non-volatile value. However, it turns
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-out that NFS devices have undependable values when an automounter
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+obviously are supposed to be a non-volatile values. However, it turns
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+out that @acronym{NFS} devices have undependable values when an automounter
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gets in the picture. This can lead to a great deal of spurious
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redumping in incremental dumps, so it is somewhat useless to compare
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-two NFS devices numbers over time. The solution implemented currently
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-is to considers all NFS devices as being equal when it comes to
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-comparing directories; this is fairly gross, but there does not seem
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-to be a better way to go.
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+two @acronym{NFS} devices numbers over time. The solution implemented
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+currently is to considers all @acronym{NFS} devices as being equal
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+when it comes to comparing directories; this is fairly gross, but
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+there does not seem to be a better way to go.
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+
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+Apart from using @acronym{NFS}, there are a number of cases where
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+relying on device numbers can cause spurious redumping of unmodified
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+files. For example, this occurs when archiving @acronym{LVM} snapshot
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+volumes. To avoid this, use @option{--no-check-device} option:
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+
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+@table @option
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+@xopindex{no-check-device, described}
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+@item --no-check-device
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+Do not rely on device numbers when preparing a list of changed files
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+for an incremental dump.
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+
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+@xopindex{check-device, described}
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+@item --check-device
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+Use device numbers when preparing a list of changed files
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+for an incremental dump. This is the default behavior. The purpose
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+of this option is to undo the effect of the @option{--no-check-device}
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+if it was given in @env{TAR_OPTIONS} environment variable
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+(@pxref{TAR_OPTIONS}).
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+@end table
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-If you are using the @i{Linux} kernel, the device numbers can also
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-change when upgrading to some newer versions of the kernel. This can
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-cause the next backup to be full backup on the affected filesystems.
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-@xref{Fixing Snapshot Files}, for the information on how to handle this case.
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+There is also another way to cope with changing device numbers. It is
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+described in detail in @ref{Fixing Snapshot Files}.
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Note that incremental archives use @command{tar} extensions and may
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not be readable by non-@acronym{GNU} versions of the @command{tar} program.
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@@ -5902,7 +5929,7 @@ their support files using the same file name that is used on the
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machine where the scripts are run (i.e., what @command{pwd} will print
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when in that directory on that machine). If the host that contains
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the file system does not have this capability, you can specify another
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-host as long as it can access the file system through NFS.
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+host as long as it can access the file system through @acronym{NFS}.
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If the list of file systems is very long you may wish to put it
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in a separate file. This file is usually named
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@@ -7285,7 +7312,7 @@ $ @kbd{tar tf arch.tar --quoting-style=literal}
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./a'single'quote
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./a"double"quote
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./a\backslash
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-./a tab
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+./a tab
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./a
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newline
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@end group
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@@ -7307,7 +7334,7 @@ $ @kbd{tar tf arch.tar --quoting-style=shell}
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'./a'\''single'\''quote'
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'./a"double"quote'
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'./a\backslash'
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-'./a tab'
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+'./a tab'
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'./a
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newline'
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@end group
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@@ -7325,7 +7352,7 @@ $ @kbd{tar tf arch.tar --quoting-style=shell-always}
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'./a'\''single'\''quote'
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'./a"double"quote'
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'./a\backslash'
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-'./a tab'
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+'./a tab'
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'./a
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newline'
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@end group
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@@ -8289,11 +8316,12 @@ $ @kbd{cat archive.tar.gz | tar tfz -}
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Notice also, that there are several restrictions on operations on
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compressed archives. First of all, compressed archives cannot be
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-modified, i.e., you cannot update (@option{--update} (@option{-u})) them or delete
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-(@option{--delete}) members from them. Likewise, you cannot append
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-another @command{tar} archive to a compressed archive using
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-@option{--append} (@option{-r})). Secondly, multi-volume archives cannot be
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-compressed.
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+modified, i.e., you cannot update (@option{--update} (@option{-u}))
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+them or delete (@option{--delete}) members from them or
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+add (@option{--append} (@option{-r})) members to them. Likewise, you
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+cannot append another @command{tar} archive to a compressed archive using
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+@option{--concatenate} (@option{-A})). Secondly, multi-volume
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+archives cannot be compressed.
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The following table summarizes compression options used by @GNUTAR{}.
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@@ -10732,7 +10760,7 @@ name=`expr $TAR_ARCHIVE : '\(.*\)-.*'`
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case $TAR_SUBCOMMAND in
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-c) ;;
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-d|-x|-t) test -r $@{name:-$TAR_ARCHIVE@}-$TAR_VOLUME || exit 1
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- ;;
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+ ;;
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*) exit 1
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esac
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Sergey Poznyakoff