SVN pre-commit hook for avoiding changes to tags subdirectories

Question

Is there anybody who has clear instructions on how to add a pre-commit hook that avoids changes to tags subdirectories?

I already searched the internet quite a bit.

Answer 1

The listed answers are great but none did exactly what I need. I want to allow creating tags easily, but once they are created they should be fully read-only.

I also want to prevent the stupid situation where if you do this:

svn copy myrepo/trunk myrepo/tags/newrelease

All is well the first time. But the second time, if the tag already exists, you will end up with myrepo/tags/newrelease/trunk.

My pre-commit hook will look for any pre-existing SVN directory matching (repo)/tags/(tag)/ and fail if it's found:

$SVNLOOK tree -N --full-paths "$REPOS" "`$SVNLOOK changed -t "$TXN" "$REPOS" \
  | sed 's/[A-Z][[:space:]]*\([^/]*\)\/tags\/\([^/]*\)\/.*/\1\/tags\/\2\//' \
  | head -n 1`" \
  && echo "Tag already exists, commit rejected." >&2 \
  && exit 1