Extracting a single file; Extended RegExes

[Simon Homer]

Dear all,

I just recently read about xar on the duplicity mailing list, and I
think that xar would be a great archive format for future versions of
duplicity.

I quickly evaluated the xar archive utility (version 1.5.1 on Fedora 7
and 8) as a replacement for tar in my daily backup script. Creating
the archive (with bzip2 compression) was about 30% faster than when I
used tar+bzip2, which is great!

However, I could not find out, how to extract a subset or a single
file from an xar archive. Is this possible at all? Or is it planned
for a future (post-1.5) release?

I also struggled a bit with the "--exclude" option.

I think it would be helpful if the man page clearly stated that "POSIX
regular expression" refers to basic regexes. For instance "man 7
regex" has the following to say about the "basic/obsolete" regexes
used in xar: "Obsolete REs mostly exist for backward compatibility in
some old programs". I was expecting xar to use extended regexes or an
option to choose between basic and extended regexes; support for Perl-
compatibel REs (PCRE) would be much appreciated.

Thanks,

Simon