Subject: Re: why use Amanda? (was: FYI: upgrading GNU tar)
To: None <,>
From: Joerg Schilling <>
List: tech-userlevel
Date: 06/22/2003 13:26:55
>flame bait?  Obviously 'pax' is now the best 'tar' program available!  ;-)

Well, pax does not even correctly implement the POSIX:1988 tar archive format
(see andthe star source) how should
it support the PAX (POSIX.1-2001 extended tar) format?

>(seriously "dump" is the best backup program available for *BSD.  I'm
>not even 100% sure POSIX 2001 extended headers can correctly represent
>all the semantics of a *BSD filesytem in a )

Well, why don't you check star?

....It already does.

>(Less seriously the Star author can't even get his facts straight.
>There can be no such thing as a "POSIX.1-2001 compliant tar
>implementation."  Even the archive format is called "ustar", not "tar",
>unless it's called "pax" or "cpio".  But then that may just be a
>misunderstanding due to the author's native language not being English. :-)

Well it seems that your native language is not English too :-(

Unfortunately POSIX removed a definition for a tar command line compliant
program but POSIX.1-2001 clearly states that the archive format of the future
is an extension to the POSIX.1-1988 TAR format (which has been called 'ustar'
in 1988). The extended format from POSIX 2001 is called 'pax'.

But: not a single pax (command) implementation does correctly support even the
POSIX.1-1988 ustar format. 

Star on the other side does correclty suopport the POSIX.1:1988 ustar format
and mostly supports the POSIX.1-2001 extended headers (the currect support for
the 'g' type headers is currently missing).

AFAIK, there is currently not a single implementation besides star that even 
started to try to support POSIX.1-2001 extended headers.

Star recently started to support 'true incremental backups' based on the same
basic ideas as ufsdump does. This is possible because star is able to archive
all inode properties using extensions to the POSIX.1-2002 extended headers.
As these extensions are tagged SCHILY.*, there may be no conflicts with other 

Star is even able to archive something I called 'meta files', a TAR extension
that allows me to archive only the files meta data and omit the file content.
This allows small inremental backups in case that only e.g. the files permission
did change.

Jörg (home) Jörg Schilling D-13353 Berlin		(uni)  If you don't have iso-8859-1	(work) chars I am J"org Schilling