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