Tar & archive formats (was Re: [WinMac] Film Bureau and Platforms)

Leonard Rosenthol(leonardr[at]lazerware.com)
Tue, 21 Sep 1999 16:31:23 -0400

At 3:29 PM +0000 9/21/99, John Droggitis wrote:
>Leonard Rosenthol wrote:
>
> > Tar, like ZIP, stores all files in a flat file structure. It
> > relies on the fact that it stores (relative) PATHNAMES to maintain
> > any true hierarchy that existed on the source device.
>
>Tar does produce a single archive that contains file entries Each
>entry contains a header that includes its pathname, statistics (including
>ownership, permissions, creation and modification dates) and
>checksum for error checking.

        Exactly what I said above. It's a FLAT FILE structure based
on pathnames rather than having actual "links" between a parent
directory and it's children. And yes, each of those entries has a
header with some basic information - but information that is
incomplete for Unix, let alone other platforms (Wintel, MacOS, etc.).

        Also, as I noted in my message, those pathnames are SHORT
(100 characters), ASCII-based, which makes storing/restoring
non-English filenames pretty much impossible. To use your
reference, see
<http://www.gnu.org/manual/tar/html_mono/tar.html#TOC112> and
<http://www.gnu.org/manual/tar/html_mono/tar.html#TOC109>).

> Directory entries are similar to file entries, so those too include
>ownership and permission info etc.

        See above comments about limited set of information...

>Tar is not limited to relative
>pathnames either, its archives can contain absolute or relative paths.

        GNU tar may support absolute pathnames, but it's not part of
the POSIX spec for tar.

        Let's also not forget about other well known limitations of
Tar such as EXTREMELY poor recovery of corrupted archives, lack of a
segmenting architecture, Unix-centricity, and of course no support
for integrated compression (NOTE: .tgz is NOT integrated compression
since it requires decompression of the entire archive before being
able to extract a single item!)

> > Tar is an outdated archiving format.
>
>Tar is as outdated as winNT is modern.

        Almost makes me want to comment about NT ;).

As the original author of StuffIt Expander, and most of the
components of the StuffIt Engine (incl. the Tar support) I stand by
my categorization of Tar and it's (lack of) usefulness as a backup
and archiving solution.

Leonard

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