(Ok, so gnu tar is a lot smarter than standard tar. But standard tar, at least on Solaris, will expand absolute paths...)

Using gnu tar (on cygwin, although it shouldn't matter)

$ mkdir a
$ cd a
$ touch a_file
$ mkdir b
$ cd b
$ touch b_file
$ tar cvf /tmp/abc.tar b_file ../a_file
$ tar cvf /tmp/abc.tar b_file ../a_file
b_file
tar: Member names contain `..'
../a_file
$ tar tvf /tmp/abc.tar
-rw-r--r-- mike/mike      0 2002-04-03 06:48:08 b_file
-rw-r--r-- mike/mike      0 2002-04-03 06:48:02 ../a_file
$ rm b_file ../a_file
$ tar xvf /tmp/abc.tar
b_file
../a_file
tar: ../a_file: Member name contains `..'
tar: Error exit delayed from previous errors
$ ls . ..
.:
b_file

..:
b
[download]

Wish I had time to download Archive::Tar to test what it would do, but I have to run to get to work.
--
Mike

I had the same error " member name contains `..' " when extracting an archive (and running it through gzip). # tar -zxvf my_tar_file.tar.gz The problem - I think - is that I created a tarball while being in some subdirectory. To cut the leading `\' from filenames I used the -P option. So the new cmd is: tar -zxvfP my_tar_file.tar.gz