Sometimes you may want your “snapshot” to be more complicated than a single directory at a single revision.
For example, pretend your project is much larger than our
calc example; suppose it contains a
number of subdirectories and many more files. In the course of your
work, you may decide that you need to create a working copy that is
designed to have specific features and bug fixes. You can accomplish
this by selectively backdating files or directories to particular
revisions (using svn update with the
-r option liberally), by switching files and
directories to particular branches (making use of svn switch), or even just by making a bunch of
local changes. When you’re done, your working copy is a hodgepodge of
repository locations from different revisions. But after testing, you
know it’s the precise combination of data you need to tag.
Time to make a snapshot. Copying one URL to another won’t work here. In this case, you want to make a snapshot of your exact working copy arrangement and store it in the repository. Luckily, svn copy actually has four different uses (which you can read about in Chapter 9), including the ability to copy a working copy tree to the repository:
$ ls my-working-copy/ $ svn copy my-working-copy \ http://svn.example.com/repos/calc/tags/mytag \ -m "Tag my existing working copy state." Committed revision 940.
Now there is a new directory in the repository, /calc/tags/mytag, which is an exact snapshot of your working copy—mixed revisions, ...