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Basic GNU `tar' Operations
==========================

   The basic `tar' operations, `--create' (`-c'), `--list' (`-t') and
`--extract' (`--get', `-x'), are currently presented and described in
the tutorial chapter of this manual.  This section provides some
complementary notes for these operations.

`--create' (`-c')
     Creating an empty archive would have some kind of elegance.  One
     can initialize an empty archive and later use `--append' (`-r')
     for adding all members.  Some applications would not welcome
     making an exception in the way of adding the first archive member.
     On the other hand, many people reported that it is dangerously
     too easy for `tar' to destroy a magnetic tape with an empty
     archive(1).  The two most common errors are:

       1. Mistakingly using `create' instead of `extract', when the
          intent was to extract the full contents of an archive.  This
          error is likely: keys `c' and `x' are right next ot each
          other on the QWERTY keyboard.  Instead of being unpacked, the
          archive then gets wholly destroyed.  When users speak about
          "exploding" an archive, they usually mean something else :-).

       2. Forgetting the argument to `file', when the intent was to
          create an archive with a single file in it.  This error is
          likely because a tired user can easily add the `f' key to the
          cluster of option letters, by the mere force of habit,
          without realizing the full consequence of doing so.  The
          usual consequence is that the single file, which was meant to
          be saved, is rather destroyed.

     So, recognizing the likelihood and the catastrophical nature of
     these errors, GNU `tar' now takes some distance from elegance, and
     cowardly refuses to create an archive when `--create' (`-c')
     option is given, there are no arguments besides options, and
     `--files-from=FILE-OF-NAMES' (`-T FILE-OF-NAMES') option is _not_
     used.  To get around the cautiousness of GNU `tar' and
     nevertheless create an archive with nothing in it, one may still
     use, as the value for the `--files-from=FILE-OF-NAMES' (`-T
     FILE-OF-NAMES') option, a file with no names in it, as shown in
     the following commands:

          tar --create --file=empty-archive.tar --files-from=/dev/null
          tar cfT empty-archive.tar /dev/null

`--extract' (`--get', `-x')
     A socket is stored, within a GNU `tar' archive, as a pipe.

`--list' (`-t')
     GNU `tar' now shows dates as `1996-08-30', while it used to show
     them as `Aug 30 1996'.  (One can revert to the old behavior by
     defining `USE_OLD_CTIME' in `src/list.c' before reinstalling.)
     But preferably, people should get used to ISO 8601 dates.  Local
     American dates should be made available again with full date
     localization support, once ready.  In the meantime, programs not
     being localizable for dates should prefer international dates,
     that's really the way to go.

     Look up <http://www.ft.uni-erlangen.de/~mskuhn/iso-time.html> if
     you are curious, it contains a detailed explanation of the ISO
     8601 standard.

   ---------- Footnotes ----------

   (1) This is well described in `Unix-haters Handbook', by Simson
Garfinkel, Daniel Weise & Steven Strassmann, IDG Books, ISBN
1-56884-203-1.