archiving (ubuntu tar) hidden directories

With wildcard it will not work. You have to specify . (current directory) if you mean full directory including hidden files. You can do

tar -cvpzf test.tgz .

The answer is that the * wildcard is handled by the shell and it just does not expand to things that start with a dot. The other wildcard ? also does not expand to things that start with a dot. Thanks to Keith for pointing out it is the shell that does the expansion and so it has nothing to do with tar.

If you use shopt -s dotglob then expansion will include things like .filename. Thanks to Andy.

Use shopt -u dotglob to turn it off.

Switching the dotglob option does not change ls itself. Rather it just changes expansion behaviour as exhibited in something like ls *.

Edit: My recommendations are in a comment below.

You can use:

tar -cvpzf test.tgz * .??*

But, this works only for hidden files with names > 2 (to prevent '.' and '..')