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@@ -1470,11 +1470,8 @@ To extract specific archive members, give their exact member names as
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arguments, as printed by @value{op-list}. If you had mistakenly deleted
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one of the files you had placed in the archive @file{collection.tar}
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earlier (say, @file{blues}), you can extract it from the archive without
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-changing the archive's structure. It will be identical to the original
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-file @file{blues} that you deleted. @FIXME{At the time of this
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-writing, atime and ctime are not restored. Since this is a tutorial
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-for a beginning user, it should hardly be mentioned here. Maybe in
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-a footnote? --gray}.
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+changing the archive's structure. Its contents will be identical to the
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+original file @file{blues} that you deleted.
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First, make sure you are in the @file{practice} directory, and list the
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files in the directory. Now, delete the file, @samp{blues}, and list
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@@ -2221,15 +2218,6 @@ Attempt to preserve the access time of files when reading them. This
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option currently is effective only on files that you own, unless you
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have superuser privileges.
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-Though this option should work on recent Linux kernel versions, it is
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-not reliable on other platforms. To preserve the access time reliably
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-on those platforms, you can mount the file system read-only, or access
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-the file system via a read-only loopback mount, or use the
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-@samp{noatime} mount option available on some systems. However,
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-mounting typically requires superuser privileges and can be a pain to
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-manage, so the @option{--atime-preserve} option can be useful despite
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-its glitches on other platforms.
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-
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@value{op-atime-preserve-replace} remembers the access time of a file
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before reading it, and then restores the access time afterwards. This
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may cause problems if other programs are reading the file at the same
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@@ -2242,24 +2230,32 @@ conditions.) Worse, on most platforms restoring the access time also
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updates the status change time, which means that this option is
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incompatible with incremental backups.
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-@value{op-atime-preserve-system} avoids changing time stamps on files
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-other than directories, without interfering with time stamp updates
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+@value{op-atime-preserve-system} avoids changing time stamps on files,
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+without interfering with time stamp updates
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caused by other programs, so it works better with incremental backups.
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However, it requires a special @code{O_NOATIME} option from the
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-underlying operating and file system implementation, and it requires
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+underlying operating and file system implementation, and it also requires
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that searching directories does not update their access times. As of
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-this writing (November 2005) this works only in a few new Linux
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-kernels. Worse, there is currently no reliable way to know whether
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-the features actually work. Sometimes @command{tar} knows for sure
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-that the features are not working, so it will complain and exit right
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-away if you try to use @value{op-atime-preserve-system}; but other
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-times @command{tar} might think that the option is supported when it
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-is not actually working.
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+this writing (November 2005) this works only with Linux, and only with
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+Linux kernels 2.6.8 and later. Worse, there is currently no reliable
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+way to know whether this feature actually works. Sometimes
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+@command{tar} knows that it does not work, and if you use
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+@value{op-atime-preserve-system} then @command{tar} complains and
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+exits right away. But other times @command{tar} might think that the
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+option works when it actually does not.
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Currently @option{--atime-preserve} with no operand defaults to
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@value{op-atime-preserve-replace}, but this may change in the future
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as support for @value{op-atime-preserve-system} improves.
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+If your operating system does not support
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+@value{op-atime-preserve-system}, you might be able to preserve access
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+times reliably by by using the @command{mount} command. For example,
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+you can mount the file system read-only, or access the file system via
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+a read-only loopback mount, or use the @samp{noatime} mount option
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+available on some systems. However, mounting typically requires
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+superuser privileges and can be a pain to manage.
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+
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@item --backup=@var{backup-type}
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Rather than deleting files from the file system, @command{tar} will
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Paul Eggert